Patent Publication Number: US-7901289-B2

Title: Transparent objects on a gaming machine

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is related to the following commonly-owned, co-pending patent applications: 
     U.S. patent application Ser. No. 10/272,854 entitled “Displaying Paylines on a Gaming Machine,” filed on Oct. 17, 2002; and 
     U.S. patent application Ser. No. 10/273,378 entitled “Payline Curves on a Gaming Machine,” filed on Oct. 17, 2002. 
     These applications are hereby incorporated by reference, in their entirety, for all purposes. 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/112,076, entitled “VIRTUAL CAMERAS AND 3-D GAMING ENVIRONMENTS IN A GAMING MACHINE” and filed Apr. 22, 2005, now U.S. Pat. No. 7,465,230 which is a continuation of U.S. patent application Ser. No. 09/927,901, entitled “VIRTUAL CAMERAS AND 3-D GAMING ENVIRONMENTS IN A GAMING MACHINE” and filed Aug. 9, 2001 (now issued as U.S. Pat. No. 6,887,157. 
     This application is a continuation of U.S. patent application Ser. No. 10/272,788, entitled, “Transparent Objects on a Gaming Machine,” by Schlottmann, et al., and filed Oct. 17, 2002, now abandoned which is incorporated herein in its entirety and for all purposes. 
     BACKGROUND 
     The present disclosure is related to presenting games on gaming machines such as reel-type slot machines, video poker machines, etc. 
     Various presentation techniques for gaming machines have been previously described. For example, U.S. Pat. No. 5,788,573 to Baerlocher et al. describes a computer-implemented electronic game. A gaming terminal is configured to display a screen with a number of areas including a puzzle completion area and a slot machine area. The slot machine area includes a number of simulated slot machine reels. In one example, multiple symbols on multiple reels are displayed. In this example, multiple possible paylines are provided. Payline indicators are displayed to indicate the various paylines. In one example, a payline indicator includes a number indicative of the payline, and a lighted portion adjacent to the symbol positions included in the payline. 
     U.S. Pat. No. 6,050,895 to Luciano, Jr. et al. describes a gaming device for a hybrid game including a coordination/dexterity portion and/or a traditional game portion. A screen that may be displayed on a display device includes a plurality of screen portions. In one portion, a representation of a golf course is displayed in connection with a simulated golf game. In another portion, a traditional game such as an electronic slot machine game is depicted. 
     Miguel A. Sepulveda, “What is OpenGL?,” LinuxFocus, Vol. 2 (January 1998) describes an application programming interface, known as “OpenGL,” for developing three dimensional (3D) graphical applications. With OpenGL, a programmer may construct mathematical descriptions of objects, and arrange the objects in a 3D scene. Additionally, the programmer can select a desired vantage point for viewing the scene, provide lighting to the scene, and color to the objects. Additionally, the programmer can use “texture mapping” to render images of realistic looking surfaces on to objects in the 3D scene. 
     SUMMARY 
     In one embodiment, a gaming apparatus is provided. The gaming apparatus may comprise a display unit, a value input device, and a controller operatively coupled to the display unit and the value input device. The controller may comprise a microprocessor and a memory operatively coupled to the microprocessor. The controller may be configured to generate a representation of a game display in a three dimensional (3D) graphics space, and to convert a view of the 3D graphics space into display data for display on the display unit, the view including the game display. The controller may also be configured to cause the display unit to display the display data, the display data including the view of the 3D graphics space, and to allow a person to make a wager. The controller may additionally be configured to cause the display unit to display a secondary display, the secondary display overlapping, at least in part, the game display, wherein the secondary display appears at least partially transparent. 
     In another embodiment, another gaming apparatus is provided. The gaming apparatus may comprise a display unit, a value input device, and a controller operatively coupled to the display unit and the value input device. The controller may comprise a microprocessor and a memory operatively coupled to the microprocessor. The controller may be configured to allow a person to make a wager, and to generate a representation of a game display on a first plane in a three dimensional (3D) graphics space. The controller may additionally be configured to generate display data for the display unit, the display data corresponding to a view in the 3D graphics space, and to determine, after the display data has been displayed, a value payout associated with an outcome of the game represented by the display data. The controller may also be configured to cause the display unit to display a secondary display, the secondary display overlapping, at least in part, the game display, wherein the secondary display appears at least partially transparent. 
     In a further embodiment, still another gaming apparatus is provided. The gaming apparatus may comprise a display unit, a value input device, and a controller operatively coupled to the display unit and the value input device. The controller may comprise a microprocessor and a memory operatively coupled to the microprocessor. The controller may be configured to generate a representation of a game display in a three dimensional (3D) graphics space, the game display corresponding to a game, and to cause the display unit to display a view of the game display in the 3D graphics space. The controller may also be configured to allow a person to make a wager, and to determine the outcome of the game. The controller may additionally be configured to determine a value payout associated with the outcome of the game, and to cause the display unit to display a secondary display, the secondary display overlapping, at least in part, the view of the game display, wherein the secondary display appears at least partially transparent. 
     In yet another embodiment, a gaming method is provided. The gaming method may comprise generating a representation of a game display in a three dimensional (3D) graphics space, and converting a view of the representation of the game display into display data for display on a display unit. The gaming method may additionally comprise determining a value payout associated with an outcome of associated with the game display, and displaying a secondary display on the display unit, the secondary display overlapping, at least in part, the view of the game display, wherein the secondary display appears at least partially transparent. 
     In still another embodiment, a memory having a computer program stored therein is provided, the computer program being capable of being used in connection with a gaming apparatus. The memory may comprise a first memory portion physically configured in accordance with computer program instructions that would cause the gaming apparatus to allow a person to make a wager, and a second memory portion physically configured in accordance with computer program instructions that would cause the gaming apparatus to convert a view of a three dimensional (3D) graphics space into display data for display on a display unit, the 3D graphics space including a representation of a game. The memory may also comprise a third memory portion physically configured in accordance with computer program instructions that would cause the gaming apparatus to display the display data on the display unit, and a fourth memory portion physically configured in accordance with computer program instructions that would cause the gaming apparatus to determine a value payout associated with an outcome of a game corresponding to the game display. The memory may further comprise a fifth memory portion physically configured in accordance with computer program instructions that would cause the gaming apparatus to display a secondary display on the display unit, the secondary display overlapping, at least in part, the view of the game display, wherein the secondary display appears at least partially transparent. 
     In yet another embodiment, a gaming apparatus is provided. The gaming method may comprise a display unit, a value input device, and a controller operatively coupled to the display unit and the value input device. The controller may comprise a microprocessor and a memory operatively coupled to the microprocessor. The controller maybe configured to cause the display unit to display a game display, and to allow a person to make a wager. The controller may additionally be configured to cause the display unit to display a secondary display, the secondary display overlapping, at least in part, the game display, wherein the secondary display appears at least partially transparent. 
     Additional aspects of the invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an embodiment of a gaming system; 
         FIG. 2  is a perspective view of an embodiment of one of the gaming units shown schematically in  FIG. 1 ; 
         FIG. 2A  illustrates an embodiment of a control panel for a gaming unit; 
         FIG. 3  is a block diagram of the electronic components of the gaming unit of  FIG. 2 ; 
         FIG. 4  is an illustration of objects in a 3-dimensional model space; 
         FIGS. 5A and 5B  illustrations of objects in a 3-dimensional model space being projected onto a 2-dimensional virtual display; 
         FIGS. 6A and 6B  are block diagrams of embodiments of a graphics processor; 
         FIG. 7  is a flowchart of an embodiment of a main routine that may be performed during operation of one or more of the gaming units; 
         FIG. 8  is a flowchart of an alternative embodiment of a main routine that may be performed during operation of one or more of the gaming units; 
         FIG. 9  is an illustration of an embodiment of a visual display that may be displayed during performance of the video poker routine of  FIG. 11 ; 
         FIG. 10  is an illustration of an embodiment of a visual display that may be displayed during performance of the video blackjack routine of  FIG. 12 ; 
         FIG. 11  is a flowchart of an embodiment of a video poker routine that may be performed by one or more of the gaming units; 
         FIG. 12  is a flowchart of an embodiment of a video blackjack routine that may be performed by one or more of the gaming units; 
         FIG. 13  is an illustration of an embodiment of a visual display that may be displayed during performance of the slots routine of  FIG. 15 ; 
         FIG. 14  is an illustration of an embodiment of a visual display that may be displayed during performance of the video keno routine of  FIG. 16 ; 
         FIG. 15  is a flowchart of an embodiment of a slots routine that may be performed by one or more of the gaming units; 
         FIG. 16  is a flowchart of an embodiment of a video keno routine that may be performed by one or more of the gaming units; 
         FIG. 17  is an illustration of an embodiment of a visual display that may be displayed during performance of the video bingo routine of  FIG. 18 ; 
         FIG. 18  is a flowchart of an embodiment of a video bingo routine that may be performed by one or more of the gaming units; 
         FIGS. 19A and 19B  are illustrations of a virtual slot machine and a payline in a 3-dimensional model space; 
         FIG. 20  is an illustration of a virtual slot machine and a payline in a 3-dimensional model space; 
         FIG. 21  is a flowchart of an embodiment of a payline generation routine; 
         FIG. 22  is a flowchart of an embodiment of a routine for generating a payline in 3-dimensional model space; 
         FIG. 23  is a flowchart of an embodiment of a routine for generating a curve comprising a plurality of triangles; 
         FIG. 24  is an illustration of a payline comprised of primitives in a 3-dimensional model space; 
         FIGS. 25A and 25B  are illustrations of a game display and an object in a 3-dimensional model space; 
         FIG. 26  is a flowchart of an embodiment of a routine for generating a transparent object on a game display; and 
         FIG. 27  is a flowchart of another embodiment of a routine for generating a transparent object on a game display. 
     
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     Although the following text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention. 
     It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘ —————— ’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. §112, sixth paragraph. 
       FIG. 1  illustrates one possible embodiment of a casino gaming system  10  in accordance with the invention. Referring to  FIG. 1 , the casino gaming system.  10  may include a first group or network  12  of casino gaming units  20  operatively coupled to a network computer  22  via a network data link or bus  24 . The casino gaming system  10  may include a second group or network  26  of casino gaming units  30  operatively coupled to a network computer  32  via a network data link or bus  34 . The first and second gaming networks  12 ,  26  may be operatively coupled to each other via a network  40 , which may comprise, for example, the Internet, a wide area network (WAN), or a local area network (LAN) via a first network link  42  and a second network link  44 . 
     The first network  12  of gaming units  20  may be provided in a first casino, and the second network  26  of gaming units  30  may be provided in a second casino located in a separate geographic location than the first casino. For example, the two casinos may be located in different areas of the same city, or they may be located in different states. The network  40  may include a plurality of network computers or server computers (not shown), each of which may be operatively interconnected. Where the network  40  comprises the Internet, data communication may take place over the communication links  42 ,  44  via an Internet communication protocol. 
     The network computer  22  may be a server computer and may be used to accumulate and analyze data relating to the operation of the gaming units  20 . For example, the network computer  22  may continuously receive data from each of the gaming units  20  indicative of the dollar amount and number of wagers being made on each of the gaming units  20 , data indicative of how much each of the gaming units  20  is paying out in winnings, data regarding the identity and gaming habits of players playing each of the gaming units  20 , etc. The network computer  32  may be a server computer and may be used to perform the same or different functions in relation to the gaming units  30  as the network computer  22  described above. 
     Although each network  12 ,  26  is shown to include one network computer  22 ,  32  and four gaming units  20 ,  30 , it should be understood that different numbers of computers and gaming units may be utilized. For example, the network  12  may include a plurality of network computers  22  and tens or hundreds of gaming units  20 , all of which may be interconnected via the data link  24 . The data link  24  may provided as a dedicated hardwired link or a wireless link. Although the data link  24  is shown as a single data link  24 , the data link  24  may comprise multiple data links. 
       FIG. 2  is a perspective view of one possible embodiment of one or more of the gaming units  20 . Although the following description addresses the design of the gaming units  20 , it should be understood that the gaming units  30  may have the same design as the gaming units  20  described below. It should be understood that the design of one or more of the gaming units  20  may be different than the design of other gaming units  20 , and that the design of one or more of the gaming units  30  may be different than the design of other gaming units  30 . Each gaming unit  20  may be any type of casino gaming unit and may have various different structures and methods of operation. For exemplary purposes, various designs of the gaming units  20  are described below, but it should be understood that numerous other designs may be utilized. 
     Referring to  FIG. 2 , the casino gaming unit  20  may include a housing or cabinet  50  and one or more input devices, which may include a coin slot or acceptor  52 , a paper currency acceptor  54 , a ticket reader/printer  56  and a card reader  58 , which may be used to input value to the gaming unit  20 . A value input device may include any device that can accept value from a customer. As used herein, the term “value” may encompass gaming tokens, coins, paper currency, ticket vouchers, credit or debit cards, and any other object representative of value. 
     If provided on the gaming unit  20 , the ticket reader/printer  56  maybe used to read and/or print or otherwise encode ticket vouchers  60 . The ticket vouchers  60  may be composed of paper or another printable or encodable material and may have one or more of the following informational items printed or encoded thereon: the casino name, the type of ticket voucher, a validation number, a bar code with control and/or security data, the date and time of issuance of the ticket voucher, redemption instructions and restrictions, a description of an award, and any other information that may be necessary or desirable. Different types of ticket vouchers  60  could be used, such as bonus ticket vouchers, cash-redemption ticket vouchers, casino chip ticket vouchers, extra game play ticket vouchers, merchandise ticket vouchers, restaurant ticket vouchers, show ticket vouchers, etc. The ticket vouchers  60  could be printed with an optically readable material such as ink, or data on the ticket vouchers  60  could be magnetically encoded. The ticket reader/printer  56  may be provided with the ability to both read and print ticket vouchers  60 , or it may be provided with the ability to only read or only print or encode ticket vouchers  60 . In the latter case, for example, some of the gaming units  20  may have ticket printers  56  that may be used to print ticket vouchers  60 , which could then be used by a player in other gaming units  20  that have ticket readers  56 . 
     If provided, the card reader  58  may include any type of card reading device, such as a magnetic card reader or an optical card reader, and may be used to read data from a card offered by a player, such as a credit card or a player tracking card. If provided for player tracking purposes, the card reader  58  may be used to read data from, and/or write data to, player tracking cards that are capable of storing data representing the identity of a player, the identity of a casino, the player&#39;s gaming habits, etc. 
     The gaming unit  20  may include one or more audio speakers  62 , a coin payout tray  64 , an input control panel  66  and a display unit  70  for displaying display data relating to the game or games provided by the gaming unit  20 . The audio speakers  62  may generate audio representing sounds such as the noise of spinning slot machine reels, a dealer&#39;s voice, music, announcements or any other audio related to a casino game. The input control panel  66  may be provided with a plurality of pushbuttons or touch-sensitive areas that may be pressed by a player to select games, make wagers, make gaming decisions, etc. The display unit  70  may be two dimensional display unit such as a color video display unit displaying images. Additionally, the display unit  70  may include a three dimensional display unit such as a holographic display, a stereoscopic display, a three dimensional display volume, etc. 
       FIG. 2A  illustrates one possible embodiment of the control panel  66 , which may be used where the gaming unit  20  is a slot machine having a plurality of mechanical or “virtual” reels. Referring to  FIG. 2A , the control panel  66  may include a “See Pays” button  72  that, when activated, causes the display unit  70  to generate one or more display screens showing the odds or payout information for the game or games provided by the gaming unit  20 . As used herein, the term “button” is intended to encompass any device that allows a player to make an input, such as an input device that must be depressed to make an input selection or a display area that a player may simply touch. The control panel  66  may include a “Cash Out” button  74  that may be activated when a player decides to terminate play on the gaming unit  20 , in which case the gaming unit  20  may return value to the player, such as by returning a number of coins to the player via the payout tray  64 . 
     If the gaming unit  20  provides a slots game having a plurality of reels and a plurality of paylines which define winning combinations of reel symbols, the control panel  66  may be provided with a plurality of selection buttons  76 , each of which allows the player to select a different number of paylines prior to spinning the reels. For example, five buttons  76  may be provided, each of which may allow a player to select one, three, five, seven or nine paylines. 
     If the gaming unit  20  provides a slots game having a plurality of reels, the control panel  66  may be provided with a plurality of selection buttons  78  each of which allows a player to specify a wager amount for each payline selected. For example, if the smallest wager accepted by the gaming unit  20  is a quarter ($0.25), the gaming unit  20  may be provided with five selection buttons  78 , each of which may allow a player to select one, two, three, four or five quarters to wager for each payline selected. In that case, if a player were to activate the “5” button  76  (meaning that five paylines were to be played on the next spin of the reels) and then activate the “3” button  78  (meaning that three coins per payline were to be wagered), the total wager would be $3.75 (assuming the minimum bet was $0.25). 
     The control panel  66  may include a “Max Bet” button  80  to allow a player to make the maximum wager allowable for a game. In the above example, where up to nine paylines were provided and up to five quarters could be wagered for each payline selected, the maximum wager would be 45 quarters, or $11.25. The control panel  66  may include a spin button  82  to allow the player to initiate spinning of the reels of a slots game after a wager has been made. 
     In  FIG. 2A , a rectangle is shown around the buttons  72 ,  74 ,  76 ,  78 ,  80 ,  82 . It should be understood that that rectangle simply designates, for ease of reference, an area in which the buttons  72 ,  74 ,  76 ,  78 ,  80 ,  82  may be located. Consequently, the term “control panel” should not be construed to imply that a panel or plate separate from the housing  50  of the gaming unit  20  is required, and the term “control panel” may encompass a plurality or grouping of player activatable buttons. 
     Although one possible control panel  66  is described above, it should be understood that different buttons could be utilized in the control panel  66 , and that the particular buttons used may depend on the game or games that could be played on the gaming unit  20 . Although the control panel  66  is shown to be separate from the display unit  70 , it should be understood that the control panel  66  could be generated by the display unit  70 . In that case, each of the buttons of the control panel  66  could be a colored area generated by the display unit  70 , and some type of mechanism may be associated with the display unit  70  to detect when each of the buttons was touched, such as a touch-sensitive screen. 
     Gaming Unit Electronics 
       FIG. 3  is a block diagram of a number of components that may be incorporated in the gaming unit  20 . Referring to  FIG. 3 , the gaming unit  20  may include a controller  100  that may comprise a program memory  102 , a microcontroller or microprocessor (MP)  104 , a random-access memory (RAM)  106 , a graphics processor  107 , and an input/output (I/O) circuit  108 , all of which may be interconnected via an address/data bus  110 . It should be appreciated that although only one microprocessor  104  is shown, the controller  100  may include multiple microprocessors  104 . Similarly, the memory of the controller  100  may include multiple RAMs  106  and multiple program memories  102 . Although the I/O circuit  108  is shown as a single block, it should be appreciated that the I/O circuit  108  may include a number of different types of I/O circuits. The RAM(s)  104  and program memories  102  may be implemented as semiconductor memories, magnetically readable memories, and/or optically readable memories, for example. 
     Although the program memory  102  is shown in  FIG. 3  as a read-only memory (ROM)  102 , the program memory of the controller  100  may be a read/write or alterable memory, such as a hard disk. In the event a hard disk is used as a program memory, the address/data bus  110  shown schematically in  FIG. 3  may comprise multiple address/data buses, which may be of different types, and there may be an I/O circuit disposed between the address/data buses. 
       FIG. 3  illustrates that the control panel  66 , the coin acceptor  52 , the bill acceptor  54 , the card reader  58 , the ticket reader/printer  56  and a graphics processor  107  may be operatively coupled to the I/O circuit  108 , each of those components being so coupled by either a unidirectional or bidirectional, single-line or multiple-line data link, which may depend on the design of the component that is used. The speaker(s)  62  may be operatively coupled to a sound circuit  112 , that may comprise a voice- and sound-synthesis circuit or that may comprise a driver circuit. The sound-generating circuit  112  may be coupled to the I/O circuit  108 . 
     As shown in  FIG. 3 , the components  52 ,  54 ,  56 ,  58 ,  66 ,  112  may be connected to the I/O circuit  108  via a respective direct line or conductor. Different connection schemes could be used. For example, one or more of the components shown in  FIG. 3  may be connected to the I/O circuit  108  via a common bus or other data link that is shared by a number of components. Furthermore, some of the components may be directly connected to the microprocessor  104  without passing through the I/O circuit  108 . 
     The graphics processor  107  may be a processor, such as a conventional graphics processor, configured to convert graphical primitives into display information that can be shown on the display unit  120 . Graphical primitives may include, for example, points, lines, polygons, etc. The graphics processor  107  maybe a KYRO II® or KYRO III® graphics and video accelerator commercially available from STMICROELECTRONICS®, Inc, a GEFORCE2® graphics processing unit commercially available from NVIDIA® Corporation, a RADEON® 7000 graphics processor commercially available from ATI Technologies Inc., etc. 
     Although the microprocessor  104  and the graphics processor  107  are shown as separate devices in  FIG. 3 , it should be noted that such a representation is merely exemplary and that the functionality of both devices could be incorporated into a single device. For example, the microprocessor could perform some or all of the operations carried out by the graphics processor  107 . 
     3D Graphics Overview 
     In a system employing 3D graphics, a scene to be displayed may be composed in a 3D model space (also referred to herein as “3D graphics space”). The scene may include a plurality of 3D objects. These 3D objects may be composed of a plurality of geometric primitives that help define the object&#39;s surface. Such primitives may include, for instance, points, lines, polygons, etc. As an example, the OpenGL graphics application programming interface, promulgated by OpenGL Architecture Review Board, provides various types of primitives that may be employed such as points, lines, line strips, line loops, polygons, quadrilaterals, polygon strips, triangles, triangle strips, and triangle fans. 
     A 3D cube may comprise, for example, of six quadrilateral primitives, corresponding to the six surfaces of the cube. A polygon that is extensively used in typical 3D graphics systems is the triangle. Thus, as another example, the 3D cube may comprise  12  triangle primitives, where each of the six surfaces of the cube comprises two triangles. By using an appropriate number of primitives, such as triangles, objects may be made to appear round, spherical, tubular, etc. Complex objects, such as a human body, may be composed of numerous primitives. 
     Primitives in the 3D model space may be indicated by the coordinates of their vertices. For example, a point may be indicated by its 3D coordinates. Also, a line may be indicated by two sets of 3D coordinates corresponding to its two endpoints. Similarly, a triangle may be indicated by three sets of 3D coordinates corresponding to its three comers. Primitives in the 3D model space may also be indicated by a primitive type (e.g., point, line, triangle, quadrilateral, etc.). The 3D model space may be described using a rectangular coordinate system or another coordinate system such as a spherical coordinate system or a cylindrical coordinate system. 
     Attributes may be assigned to objects or primitives in the 3D model space. Attributes may include color, pattern, reflectance, transparency, translucency, animation, texture, etc. Textures may include smoothness, surface irregularities such as bumps, craters, etc., and may also include the mapping of text, an image, bitmap, animation, video, etc., onto the object or primitive. 
       FIG. 4  is an illustration of an example of objects in a model space. The model space  100  includes a cube  102  on a plane  104 . The cube  102  comprises surface polygons  106 ,  108 , and  110 . Model space  100  also includes a light source  114 , which causes cube  102  to cast a shadow  118  onto plane  104 . The shadow  118  may be represented as one or more 3D primitives having a darker shade. Additionally, polygon  110  is not illuminated by light source  114 , and therefore may appear shaded. 
     Model space  100  can be viewed from various viewpoints such as viewpoints  122 ,  124 , and  126 . To display a depiction of model space  100  on a display unit, a view point maybe chosen, and a depiction of the model space  100  as viewed from that viewpoint may be generated. 
     A typical technique for generating a depiction of the model space  100  from a particular viewpoint is to “project” the model space  100  onto a virtual display. For example, if the viewpoint is to be viewed on a 2D display such as a monitor, the model space  100  (or a portion thereof) may be “projected” onto a virtual 2D display.  FIGS. 5A and 5B  illustrate an example of objects  140  and  150  in 3D model space being “projected” onto a virtual 2D display  144 . Typically, the projection of an object in 3D model space onto a 2D virtual screen is implemented by “projecting” 3D primitives of which it is comprised. Typically, a mathematical transform is applied to the 3D coordinates of each primitive&#39;s vertices to generate the 2D coordinates of the projection&#39;s vertices on the virtual 2D display  144 . Thus, application of the mathematical transform may generate primitives in a 2D space (hereinafter “2D primitives”). Additional computations may be performed to generate the effects of light sources, if any, in 3D space on the color, luminance, etc., associated with the generated 2D primitives. These mathematical transformations may be included in a 3D graphics processing step typically known to those of ordinary skill in the art as “Transform and Lighting.”  FIG. 8B  illustrates the projection of cube  140  onto the virtual display  144 . In this example, the projection comprises two polygons  146  and  148 . Because the virtual display  144  is a 2D space, polygons  146  and  148  can be indicated by sets of 2D coordinates. 
     The Transform and Lighting processing step generally may produce data including information relating to 2D primitives. This data relating to a 2D primitive may include the 2D coordinates of its vertices, the primitive&#39;s color, luminance, etc. 
     The data may also include depth information of the primitive in terms of the 3D model space and the viewpoint. This depth information can help determine whether a particular primitive, or part of the primitive, is blocked from view by another primitive. Referring again to  FIGS. 5A and 5B , depth may increase going “into” the 3D space from the virtual display  144 . Thus, object  150  maybe at a greater depth than object  140 . Similarly, the depth information associated with projected polygon  152  may indicate a greater depth than that of polygons  146  and  148 . Therefore, if object  140  is opaque, polygon  152  is hidden and may not be displayed on the display unit. 
     The data relating to a 2D primitive may also include transparency information, such as a value that indicates the degree of transparency of the primitive. In some typical 3D graphic systems, a primitive&#39;s “alpha value” indicates the degree of the primitive&#39;s transparency. Frequently, the alpha value may be between the values 0 and 1, inclusive, where, for example, a 0 indicates the primitive is completely transparent and a 1 indicates the primitive is completely opaque. In other 3D graphics systems, the transparency information, may merely include a flag that indicates whether or not the primitive is transparent, and the degree of transparency is the same for all transparent primitives. For example, the degree of transparency may be fixed at 50% for transparent objects. In 3D graphics systems that employ “alpha values,” a technique often referred to as “alpha blending” may be used to generate a display in which an object appears to be transparent when viewed on the display unit. 
     Referring now to  FIGS. 3 ,  6 A, and  6 B, two examples of graphics processors that may be used in the gaming unit  20  are illustrated.  FIG. 6A  illustrates a graphics processor  107 A configured to receive information relating to 2D primitives from, for example, microprocessor  104 . The graphics processor  107 A may generate one or more control signals for driving display unit  70 . With the graphics processor  107 A, the transform and lighting step may be implemented, for example, with the microprocessor  104 . Optionally, graphics processors  107 A and  107 B may be configured to receive an overlay input. The overlay input may be used to provide an image that is to overlay a base image. Additionally, graphics processors  107 A and  107 B may be configured to optionally overlay the image such that it appears transparent. 
       FIG. 6B  illustrates a graphics processor  107 B configured to receive information that may include information relating to 3D primitives, point of view, and lighting (if any). This information may be received, for example, from microprocessor  104 . In this example, the graphics processor  107 B may implement the “Transform and Lighting” processing step described above. It is to be understood that 3D graphics processing implementation can be partitioned between the graphics processor  107  and the microprocessor  104  in any number of ways. For example, much of the processing typically implemented by commercially available graphics processors could be implemented by the microprocessor  104 , thus eliminating or reducing the cost of graphics processor  107 . 
     Details of 3D graphical techniques that may be used are described in “OpenGL Reference Manual: The Official Reference Document to Open GL, Version 1.2,” 3 rd  edition, Dave Shreiner (editor), OpenGL Architecture Review Board, Addison-Wesley Publishing, Co., 1999, ISBN: 0201657651 and “OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 1.2,” 3 rd  edition, Mason Woo et al. (editors), OpenGL Architecture Review Board, Addison-Wesley Publishing Co., 1999, ISBN: 0201604582, which are hereby incorporated by reference in their entirety for all purposes. 
     Additional detail pertinent to 3D graphics is available in commonly assigned U.S. patent application Ser. No. 09/927,901 (Client Reference No. P-557), entitled “Virtual Cameras and 3-D Gaming Environments in a Gaming Machine,” filed Aug. 9, 2001, which is hereby incorporated by reference in its entirety for all purposes. 
     Overall Operation of Gaming Unit 
     One manner in which one or more of the gaming units  20  (and one or more of the gaming units  30 ) may operate is described below in connection with a number of flowcharts which represent a number of portions or routines of one or more computer programs, which may be stored in one or more of the memories of the controller  100 . The computer programs) or portions thereof may be stored remotely, outside of the gaming unit  20 , and may control the operation of the gaming unit  20  from a remote location. Such remote control may be facilitated with the use of a wireless connection, or by an Internet interface that connects the gaming unit  20  with a remote computer (such as one of the network computers  22 ,  32 ) having a memory in which the computer program portions are stored. The computer program portions may be written in any high level language such as C, C+, C++ or the like or any low-level, assembly or machine language. By storing the computer program portions therein, various portions of the memories  102 ,  106  are physically and/or structurally configured in accordance with computer program instructions. 
       FIG. 7  is a flowchart of a main operating routine  200  that may be stored in the memory of the controller  100 . Referring to  FIG. 7 , the main routine  200  may begin operation at block  202  during which an attraction sequence may be performed in an attempt to induce a potential player in a casino to play the gaming unit  20 . The attraction sequence may be performed by displaying one or more video images on the display unit  70  and/or causing one or more sound segments, such as voice or music, to be generated via the speakers  62 . The attraction sequence may include a scrolling list of games that may be played on the gaming unit  20  and/or video images of various games being played, such as video poker, video blackjack, video slots, video keno, video bingo, etc. 
     During performance of the attraction sequence, if a potential player makes any input to the gaming unit  20  as determined at block  204 , the attraction sequence may be terminated and a game-selection display maybe generated on the display unit  70  at block  206  to allow the player to select a game available on the gaming unit  20 . The gaming unit  20  may detect an input at block  204  in various ways. For example, the gaming unit  20  could detect if the player presses any button on the gaming unit  20 ; the gaming unit  20  could determine if the player deposited one or more coins into the gaming unit  20 ; the gaming unit  20  could determine if player deposited paper currency into the gaming unit; etc. 
     The game-selection display generated at block  206  may include, for example, a list of video games that may be played on the gaming unit  20  and/or a visual message to prompt the player to deposit value into the gaming unit  20 . While the game-selection display is generated, the gaming unit  20  may wait for the player to make a game selection. Upon selection of one of the games by the player as determined at block  208 , the controller  100  may cause one of a number of game routines to be performed to allow the selected game to be played. For example, the game routines could include a video poker routine  210 , a video blackjack routine  220 , a slots routine  230 , a video keno routine  240 , and a video bingo routine  250 . At block  208 , if no game selection is made within a given period of time, the operation may branch back to block  202 . 
     After one of the routines  210 ,  220 ,  230 ,  240 ,  250  has been performed to allow the player to play one of the games, block  260  may be utilized to determine whether the player wishes to terminate play on the gaming unit  20  or to select another game. If the player wishes to stop playing the gaming unit  20 , which wish may be expressed, for example, by selecting a “Cash Out” button, the controller  100  may dispense value to the player at block  262  based on the outcome of the game(s) played by the player. The operation may then return to block  202 . If the player did not wish to quit as determined at block  260 , the routine may return to block  208  where the game-selection display may again be generated to allow the player to select another game. 
     It should be noted that although five gaming routines are shown in  FIG. 7 , a different number of routines could be included to allow play of a different number of games. The gaming unit  20  may also be configured to allow play of different games. 
       FIG. 8  is a flowchart of an alternative main operating routine  300  that may be stored in the memory of the controller  100 . The main routine  300  may be utilized for gaming units  20  that are designed to allow play of only a single game or single type of game. Referring to  FIG. 8 , the main routine  300  may begin operation at block  302  during which an attraction sequence may be performed in an attempt to induce a potential player in a casino to play the gaming unit  20 . The attraction sequence may be performed by displaying one or more video images on the display unit  70  and/or causing one or more sound segments; such as voice or music, to be generated via the speakers  62 . 
     During performance of the attraction sequence, if a potential player makes any input to the gaming unit  20  as determined at block  304 , the attraction sequence may be terminated and a game display may be generated on the display unit  70  at block  306 . The game display generated at block  306  may include, for example, an image of the casino game that may be played on the gaming unit  20  and/or a visual message to prompt the player to deposit value into the gaming unit  20 . At block  308 , the gaming unit  20  may determine if the player requested information concerning the game, in which case the requested information may be displayed at block  310 . Block  312  may be used to determine if the player requested initiation of a game, in which case a game routine  320  maybe performed. The game routine  320  could be any one of the game routines disclosed herein, such as one of the five game routines  210 ,  220 ,  230 ,  240 ,  250 , or another game routine. 
     After the routine  320  has been performed to allow the player to play the game, block  322  may be utilized to determine whether the player wishes to terminate play on the gaming unit  20 . If the player wishes to stop playing the gaming unit  20 , which wish may be expressed, for example, by selecting a “Cash Out” button, the controller  100  may dispense value to the player at block  324  based on the outcome of the game(s) played by the player. The operation may then return to block  302 . If the player did not wish to quit as determined at block  322 , the operation may return to block  308 . 
     Video Poker 
       FIG. 9  is an exemplary display  350  that may be shown on the display unit  70  during performance of the video poker routine  210  shown schematically in  FIG. 7 . Referring to  FIG. 9 , the display  350  may include video images  352  of a plurality of playing cards representing the player&#39;s hand, such as five cards. To allow the player to control the play of the video poker game, a plurality of player-selectable buttons maybe displayed. The buttons may include a “Hold” button  354  disposed directly below each of the playing card images  352 , a “Cash Out” button  356 , a “See Pays” button  358 , a “Bet One Credit” button  360 , a “Bet Max Credits” button  362 , and a “Deal/Draw” button  364 . The display  350  may also include an area  366  in which the number of remaining credits or value is displayed. If the display unit  70  is provided with a touch-sensitive screen, the buttons  354 ,  356 ,  358 ,  360 ,  362 ,  364  may form part of the video display  350 . Alternatively, one or more of those buttons maybe provided as part of a control panel that is provided separately from the display unit  70 . 
       FIG. 11  is a flowchart of the video poker routine  210  shown schematically in  FIG. 7 . Referring to  FIG. 11 , at block  370 , the routine may determine whether the player has requested payout information, such as by activating the “See Pays” button  358 , in which case at block  372  the routine may cause one or more pay tables to be displayed on the display unit  70 . At block  374 , the routine may determine whether the player has made a bet, such as by pressing the “Bet One Credit” button  360 , in which case at block  376  bet data corresponding to the bet made by the player may be stored in the memory of the controller  100 . At block  378 , the routine may determine whether the player has pressed the “Bet Max Credits” button  362 , in which case at block  380  bet data corresponding to the maximum allowable bet may be stored in the memory of the controller  100 . 
     At block  382 , the routine may determine if the player desires a new hand to be dealt, which may be determined by detecting if the “Deal/Draw” button  364  was activated after a wager was made. In that case, at block  384  a video poker hand may be “dealt” by causing the display unit  70  to generate the playing card images  352 . After the hand is dealt, at block  386  the routine may determine if any of the “Hold” buttons  354  have been activated by the player, in which case data regarding which of the playing card images  352  are to be “held” may be stored in the controller  100  at block  388 . If the “Deal/Draw” button  364  is activated again as determined at block  390 , each of the playing card images  352  that was not “held” may be caused to disappear from the video display  350  and to be replaced by a new, randomly selected, playing card image  352  at block  392 . 
     At block  394 , the routine may determine whether the poker hand represented by the playing card images  352  currently displayed is a winner. That determination may be made by comparing data representing the currently displayed poker hand with data representing all possible winning hands, which may be stored in the memory of the controller  100 . If there is a winning hand, a payout value corresponding to the winning hand may be determined at block  396 . At block  398 , the player&#39;s cumulative value or number of credits may be updated by subtracting the bet made by the player and adding, if the hand was a winner, the payout value determined at block  396 . The cumulative value or number of credits may also be displayed in the display area  366  ( FIG. 9 ). 
     Although the video poker routine  210  is described above in connection with a single poker hand of five cards, the routine  210  may be modified to allow other versions of poker to be played. For example, seven card poker may be played, or stud poker may be played. Alternatively, multiple poker hands may be simultaneously played. In that case, the game may begin by dealing a single poker hand, and the player may be allowed to hold certain cards. After deciding which cards to hold, the held cards may be duplicated in a plurality of different poker hands, with the remaining cards for each of those poker hands being randomly determined. 
     Video Blackjack 
       FIG. 10  is an exemplary display  400  that may be shown on the display unit  70  during performance of the video blackjack routine  220  shown schematically in  FIG. 7 . Referring to  FIG. 10 , the display  400  may include video images  402  of a pair of playing cards representing a dealer&#39;s hand, with one of the cards shown face up and the other card being shown face down, and video images  404  of a pair of playing cards representing a player&#39;s hand, with both the cards shown face up. The “dealer” may be the gaming unit  20 . 
     To allow the player to control the play of the video blackjack game, a plurality of player-selectable buttons may be displayed. The buttons may include a “Cash Out” button  406 , a “See Pays” button  408 , a “Stay” button  410 , a “Hit” button  412 , a “Bet One Credit” button  414 , and a “Bet Max Credits” button  416 . The display  400  may also include an area  41   8  in which the number of remaining credits or value is displayed. If the display unit  70  is provided with a touch-sensitive screen, the buttons  406 ,  408 ,  410 ,  412 ,  414 ,  416  may form part of the video display  400 . Alternatively, one or more of those buttons may be provided as part of a control panel that is provided separately from the display unit  70 . 
       FIG. 12  is a flowchart of the video blackjack routine  220  shown schematically in  FIG. 7 . Referring to  FIG. 12 , the video blackjack routine  220  may begin at block  420  where it may determine whether a bet has been made by the player. That may be determined, for example, by detecting the activation of either the “Bet One Credit” button  414  or the “Bet Max Credits” button  416 . At block  422 , bet data corresponding to the bet made at block  420  may be stored in the memory of the controller  100 . At block  424 , a dealer&#39;s hand and a player&#39;s hand may be “dealt” by making the playing card images  402 ,  404  appear on the display unit  70 . 
     At block  426 , the player may be allowed to be “hit,” in which case at block  428  another card will be dealt to the player&#39;s hand by making another playing card image  404  appear in the display  400 . If the player is hit, block  430  may determine if the player has “bust,” or exceeded  21 . If the player has not bust, blocks  426  and  428  may be performed again to allow the player to be hit again. 
     If the player decides not to hit, at block  432  the routine may determine whether the dealer should be hit. Whether the dealer hits may be determined in accordance with predetermined rules, such as the dealer always hit if the dealer&#39;s hand totals 15 or less. If the dealer hits, at block  434  the dealer&#39;s hand may be dealt another card by making another playing card image  402  appear in the display  400 . At block  436  the routine may determine whether the dealer has bust. If the dealer has not bust, blocks  432 ,  434  may be performed again to allow the dealer to be hit again. 
     If the dealer does not hit, at block  436  the outcome of the blackjack game and a corresponding payout may be determined based on, for example, whether the player or the dealer has the higher hand that does not exceed 21. If the player has a winning hand, a payout value corresponding to the winning hand may be determined at block  440 . At block  442 , the player&#39;s cumulative value or number of credits may be updated by subtracting the bet made by the player and adding, if the player won, the payout value determined at block  440 . The cumulative value or number of credits may also be displayed in the display area  418  ( FIG. 10 ). 
     Video Slots 
       FIG. 13  is an exemplary display  450  that may be shown on the display unit  70  during performance of the slots routine  230  shown schematically in  FIG. 7 . Referring to  FIG. 13 , the display  450  may include video images  452  of a plurality of slot machine reels, each of the reels having a plurality of reel symbols  454  associated therewith. Although the display  450  shows five reel images  452 , each of which may have three reel symbols  454  that are visible at a time, other reel configurations could be utilized. For example, U.S. Pat. No. 6,413,162 to Baerlocher et al. describes a gaming device having unisymbol display reels. Each symbol on a display of the gaming device represents, or is included on, a different reel. In one specific example, U.S. Pat. No. 6,413,162 describes displaying eighteen independent unisymbol reels, each capable of randomly generating and displaying one of a plurality of symbols. In another example, U.S. Pat. No. 6,413,162 describes unisymbol reels displayed in concentric circles. 
     To allow the player to control the play of the slots game, a plurality of player-selectable buttons may be displayed. The buttons may include a “Cash Out” button  456 , a “See Pays” button  458 , a plurality of payline-selection buttons  460  each of which allows the player to select a different number of paylines prior to “spinning” the reels, a plurality of bet-selection buttons  462  each of which allows a player to specify a wager amount for each payline selected, a “Spin” button  464 , and a “Max Bet” button  466  to allow a player to make the maximum wager allowable. 
       FIG. 15  is a flowchart of the slots routine  230  shown schematically in  FIG. 13 . Referring to  FIG. 15 , at block  470 , the routine may determine whether the player has requested payout information, such as by activating the “See Pays” button  458 , in which case at block  472  the routine may cause one or more pay tables to be displayed on the display unit  70 . At block  474 , the routine may determine whether the player has pressed one of the payline-selection buttons  460 , in which case at block  476  data corresponding to the number of paylines selected by the player may be stored in the memory of the controller  100 . At block  478 , the routine may determine whether the player has pressed one of the bet-selection buttons  462 , in which case at block  480  data corresponding to the amount bet per payline may be stored in the memory of the controller  100 . At block  482 , the routine may determine whether the player has pressed the “Max Bet” button  466 , in which case at block  484  bet data (which may include both payline data and bet-per-payline data) corresponding to the maximum allowable bet maybe stored in the memory of the controller  100 . 
     If the “Spin” button  464  has been activated by the player as determined at block  486 , at block  488  the routine may cause the slot machine reel images  452  to begin “spinning” so as to simulate the appearance of a plurality of spinning mechanical slot machine reels. At block  490 , the routine may determine the positions at which the slot machine reel images will stop, or the particular symbol images  454  that will be displayed when the reel images  452  stop spinning. At block  492 , the routine may stop the reel images  452  from spinning by displaying stationary reel images  452  and images of three symbols  454  for each stopped reel image  452 . The virtual reels may be stopped from left to right, from the perspective of the player, or in any other manner or sequence. After the routine stops the reel images  452  are block  492 , paylines associated with winning symbols combinations may be generated and displayed to the user at block  493 . 
     The payline generation routine  493 , which is described in further detail in conjunction with  FIGS. 19A-24 , is responsible for generating 3-D representations of the paylines that overlay game displays. Additionally, the payline generation routine  493  converts the 3-D representations into 2-D graphics that may be presented to a user on the display  70  ( FIG. 3 ). Although, by way of example, the payline generation routine  493  is shown as being called between blocks  492  and  494 , it will be readily appreciated that the payline generation routine  493  could be called at any other point in the routine  230 . Additionally, the payline generation routine  493  could be called more than just once at different locations in the routine  230 . For example, the payline generation routine  493  could be called at any location at which it is desirable to display paylines to the user. 
     The routine  230  may provide for the possibility of a bonus game or round if certain conditions are met, such as the display in the stopped reel images  452  of a particular symbol  454 . If there is such a bonus condition as determined at block  494 , the routine may proceed to block  496  where a bonus round may be played. The bonus round may be a different game than slots, and many other types of bonus games could be provided. If the player wins the bonus round, or receives additional credits or points in the bonus round, a bonus value may be determined at block  498 . A payout value corresponding to outcome of the slots game and/or the bonus round may be determined at block  500 . At block  502 , the player&#39;s cumulative value or number of credits may be updated by subtracting the bet made by the player and adding, if the slot game and/or bonus round was a winner, the payout value determined at block  500 . 
     Although the above routine has been described as a virtual slot machine routine in which slot machine reels are represented as images on the display unit  70 , actual slot machine reels that are capable of being spun maybe utilized instead. 
     Video Keno 
       FIG. 14  is an exemplary display  520  that may be shown on the display unit  70  during performance of the video keno routine  240  shown schematically in  FIG. 7 . Referring to FIG.  14 , the display  520  may include a video image  522  of a plurality of numbers that were selected by the player prior to the start of a keno game and a video image  524  of a plurality of numbers randomly selected during the keno game. The randomly selected numbers may be displayed in a grid pattern. 
     To allow the player to control the play of the keno game, a plurality of player-selectable buttons may be displayed. The buttons may include a “Cash Out” button  526 , a “See Pays” button  528 , a “Bet One Credit” button  530 , a “Bet Max Credits” button  532 , a “Select Ticket” button  534 , a “Select Number” button  536 , and a “Play” button  538 . The display  520  may also include an area  540  in which the number of remaining credits or value is displayed. If the display unit  70  is provided with a touch-sensitive screen, the buttons may form part of the video display  520 . Alternatively, one or more of those buttons may be provided as part of a control panel that is provided separately from the display unit  70 . 
       FIG. 16  is a flowchart of the video keno routine  240  shown schematically in  FIG. 7 . The keno routine  240  may be utilized in connection with a single gaming unit  20  where a single player is playing a keno game, or the keno routine  240  may be utilized in connection with multiple gaming units  20  where multiple players are playing a single keno game. In the latter case, one or more of the acts described below may be performed either by the controller  100  in each gaming unit or by one of the network computer  22 ,  32  to which multiple gaming units  20  are operatively connected. 
     Referring to  FIG. 16 , at block  550 , the routine may determine whether the player has requested payout information, such as by activating the “See Pays” button  528 , in which case at block  552  the routine may cause one or more pay tables to be displayed on the display unit  70 . At block  554 , the routine may determine whether the player has made a bet, such as by having pressed the “Bet One Credit” button  530  or the “Bet Max Credits” button  532 , in which case at block  556  bet data corresponding to the bet made by the player may be stored in the memory of the controller  100 . After the player has made a wager, at block  558  the player may select a keno ticket, and at block  560  the ticket may be displayed on the display  520 . At block  562 , the player may select one or more game numbers, which may be within a range set by the casino. After being selected, the player&#39;s game numbers may be stored in the memory of the controller  100  at block  564  and may be included in the image  522  on the display  520  at block  566 . After a certain amount of time, the keno game may be closed to additional players (where a number of players are playing a single keno game using multiple gambling units  20 ). 
     If play of the keno game is to begin as determined at block  568 , at block  570  a game number within a range set by the casino may be randomly selected either by the controller  100  or a central computer operatively connected to the controller, such as one of the network computers  22 ,  32 . At block  572 , the randomly selected game number may be displayed on the display unit  70  and the display units  70  of other gaming units  20  (if any) which are involved in the same keno game. At block  574 , the controller  100  (or the central computer noted above) may increment a count which keeps track of how many game numbers have been selected at block  570 . At block  576 , the controller  100  (or one of the network computers  22 ,  32 ) may determine whether a maximum number of game numbers within the range have been randomly selected. If not, another game number may be randomly selected at block  570 . If the maximum number of game numbers has been selected, at block  578  the controller  100  (or a central computer) may determine whether there are a sufficient number of matches between the game numbers selected by the player and the game numbers selected at block  570  to cause the player to win. The number of matches may depend on how many numbers the player selected and the particular keno rules being used. 
     If there are a sufficient number of matches, a payout may be determined at block  580  to compensate the player for winning the game. The payout may depend on the number of matches between the game numbers selected by the player and the game numbers randomly selected at block  570 . At block  582 , the player&#39;s cumulative value or number of credits may be updated by subtracting the bet made by the player and adding, if the keno game was won, the payout value determined at block  580 . The cumulative value or number of credits may also be displayed in the display area  540  ( FIG. 14 ). 
     Video Bingo 
       FIG. 17  is an exemplary display  600  that may be shown on the display unit  70  during performance of the video bingo routine  250  shown schematically in  FIG. 7 . Referring to  FIG. 17 , the display  600  may include one or more video images  602  of a bingo card and images of the bingo numbers selected during the game. The bingo card images  602  may have a grid pattern. 
     To allow the player to control the play of the bingo game, a plurality of player-selectable buttons may be displayed. The buttons may include a “Cash Out” button  604 , a “See Pays” button  606 , a “Bet One Credit” button  608 , a “Bet Max Credits” button  610 , a “Select Card” button  612 , and a “Play” button  614 . The display  600  may also include an area  616  in which the number of remaining credits or value is displayed. If the display unit  70  is provided with a touch-sensitive screen, the buttons may form part of the video display  600 . Alternatively, one or more of those buttons may be provided as part of a control panel that is provided separately from the display unit  70 . 
       FIG. 18  is a flowchart of the video bingo routine  250  shown schematically in  FIG. 7 . The bingo routine  250  may be utilized in connection with a single gaming unit  20  where a single player is playing a bingo game, or the bingo routine  250  may be utilized in connection with multiple gaming units  20  where multiple players are playing a single bingo game. In the latter case, one or more of the acts described below may be performed either by the controller  100  in each gaming unit  20  or by one of the network computers  22 ,  32  to which multiple gaming units  20  are operatively connected. Referring to  FIG. 18 , at block  620 , the routine may determine whether the player has requested payout information, such as by activating the “See Pays” button  606 , in which case at block  622  the routine may cause one or more pay tables to be displayed on the display unit  70 . At block  624 , the routine may determine whether the player has made a bet, such as by having pressed the “Bet One Credit” button  608  or the “Bet Max Credits” button  610 , in which case at block  626  bet data corresponding to the bet made by the player may be stored in the memory of the controller  100 . 
     After the player has made a wager, at block  628  the player may select a bingo card, which may be generated randomly. The player may select more than one bingo card, and there may be a maximum number of bingo cards that a player may select. After play is to commence as determined at block  632 , at block  634  a bingo number may be randomly generated by the controller  100  or a central computer such as one of the network computers  22 ,  32 . At block  636 , the bingo number may be displayed on the display unit  70  and the display units  70  of any other gaming units  20  involved in the bingo game. 
     At block  638 , the controller  100  (or a central computer) may determine whether any player has won the bingo game. If no player has won, another bingo number may be randomly selected at block  634 . If any player has bingo as determined at block  638 , the routine may determine at block  640  whether the player playing that gaming unit  20  was the winner. If so, at block  642  a payout for the player may be determined. The payout may depend on the number of random numbers that were drawn before there was a winner, the total number of winners (if there was more than one player), and the amount of money that was wagered on the game. At block  644 , the player&#39;s cumulative value or number of credits may be updated by subtracting the bet made by the player and adding, if the bingo game was won, the payout value determined at block  642 . The cumulative value or number of credits may also be displayed in the display area  616  ( FIG. 17 ). 
     Payline Generation 
     Examples of techniques for generating paylines will now be described. For ease of explanation, these examples are described in the context of a reel-type slot machine game. It will be appreciated by one of ordinary skill in the art, however, that paylines can be used in other games as well. For example, techniques similar to those described below can be used to generate paylines in games, such as checkers and Othello, to indicate how a player won the game. 
       FIGS. 19A and 19B  illustrate an example of a virtual slot machine and a payline in 3D model space. In particular, the virtual slot machine model includes an object  660  with a flat face  662 . An image (or images) of slot reels may be mapped onto face  662 . For instance, in the example of  FIG. 19A , an image (or images) .of four slot reels is (are) mapped onto face  662 , where three symbols on each reel are visible. During a game, the image (or images) of slot reels on face  662  may mimic the rotation of reels on a mechanical slot machine. Additionally,  FIG. 19A  illustrates a payline  664 .  FIG. 19B  illustrates object  660  and payline  664  as viewed from the side of object  660 . From viewpoint  668 , payline  664  appears to be in front of object  660 . 
     The image or images of slot reels need not be mapped onto the face  662  of an object  660 . For example, the images of slot reels could be mapped onto a plane. Additionally, although the example of  FIGS. 19A and 19B  illustrate the virtual slot machine modeled as an image or images mapped onto a flat face, the virtual slot machine can be modeled in other ways as well.  FIG. 20  illustrates another example of a virtual slot machine and a payline in 3D model space. The model  670  of virtual slot machine includes three reels modeled as three cylinders  672 ,  674 , and  676 . Each reel has mapped on it an image or images of symbols. The model  670  also includes a payline  678  that passes through reference points  680 ,  682 , and  684 . 
     Turning now to  FIGS. 3 ,  6 A,  6 B,  19 A,  19 B, and  20 , microprocessor  104  may generate a 3D model of a slot machine game. The 3D model may include virtual slot reels and one or more paylines.  FIGS. 19A ,  19 B, and  20  illustrate examples of 3D models of slot machine including virtual slot reels and paylines. 
     Microprocessor  104  may generate 3D primitives corresponding to the virtual slot reels and the payline. In some embodiments, these 3D primitives are provided to a graphics processor  107 , along with other information such as lighting information. In these embodiments, the graphics processor  107  may perform “Transform and Lighting” processing on the 3D primitives, and may generate a signal for causing display unit  70  to display an image of the virtual slot reels and the payline. In other embodiments, microprocessor  104  may perform “Transform and Lighting” processing on the 3D primitives to generate 2D primitives. In these embodiments, these 2D primitives may be provided to graphics processor  107 , which may generate a signal for causing display unit  70  to display an image of the virtual slot reels and the payline. 
     As described above with reference to  FIG. 15 , a payline or paylines may be generated after the reels of the virtual slot machine stop spinning, and if the player has won.  FIG. 21  is one embodiment of a method  493  for generating a payline. Method  493  will be described with reference to  FIG. 24 . In some embodiments, method  493  may be implemented by microprocessor  104  in conjunction with graphics processor  107 . 
     At block  700 , locations of reference points in 3D model space of the payline may be determined. For example, in  FIG. 24 , the locations of reference points  680 ,  682  and  684  may be generated, retrieved from a look-up table, etc. In some embodiments, the reference points generated at block  700  may be between the virtual reels of the slot machine and the viewpoint. 
     At block  702 , payline properties may be defined. The payline properties may include one or more (or none) of, but are not limited to, payline width, payline curve radius, the number of polygons to be used to define curves, etc. Alternatively, or additionally, other payline properties may include payline thickness, distance from the reel face, etc. The payline properties may be defined ahead of time and stored in, for example, memory  102  or memory  106  ( FIG. 3 ). Then, during operation, the payline properties can be retrieved from memory. 
     At block  704 , a payline may be generated in 3D model space. One embodiment of a method for generating the payline in 3D model space will be described subsequently with reference to  FIG. 22 . At block  706 , graphics attributes may be associated with the payline. Such attributes may include, for example, color, texture, texture mapping, transparency, translucency, etc. One or more, or none, of these attributes (or other attributes) can be associated with the payline. Using various graphics attributes, the payline can be made to appear to oscillate, move, rotate, pivot, slide on the screen, flash, fade in, fade out, shrink, grow, etc. Similarly, the scale of the payline in various dimensions may be changed. Additionally, the payline may appear to be on fire, be drawn by a laser, or the payline&#39;s colors may appear to change. Also, a varying transparency effect can be employed to help make the payline edges appear smooth. Further, the payline may appear to morph into different shapes. For example, the payline may appear to morph to include boxes around winning symbols in a reel-type slot machine game. 
     At block  708 , the payline may be displayed. If a graphics processor such as the graphics processor  107 B of  FIG. 6B  is used, displaying the payline may include providing the 3D primitive information generated at block  704  to the graphics processor  107 . This may also include providing the effects information associated with the payline (block  706 ) to the graphics processor  107 . If a graphics processor such at the graphics processor  107 A is used, displaying the payline may include the microprocessor performing “Transform and Lighting” processing on the 3D primitive information generated at block  704  to generate 2D primitive information. Then, the 2D primitive information may be provided to graphics processor  107 . Next, graphics processor  107  generates one or more control signals that control display unit  70  to display an image of the slot reels and the payline. 
       FIG. 22  is a flow diagram illustrating one embodiment of a method  704  for generating a payline in 3D model space. Method  704  will be described with reference to  FIG. 24 . At block  720 , one of the reference points generated at block  700  ( FIG. 21 ) may be selected as a current reference point. For example, in  FIG. 24 , reference point  752  may be selected as the current reference point. 
     At block  724 , a current slope may be generated. In  FIG. 24 , for example, the  30  current slope may be the slope between reference points  752  and  754 . At block  726 , a prior slope may be set to the current slope. 
     At block  728 , it may be determined whether there is a next reference point. For example, in  FIG. 24 , if reference point  752  is the current reference point, reference point  754  may be considered a next reference point. If there is no next reference point, the routine may end. If there is a next reference point, control may pass to block  730 . 
     At block  730 , a next slope may be calculated. In  FIG. 24 , for example, the next slope may be the slope between reference points  754  and  756 . 
     At block  732 , it may be determined whether the current slope is the same as the prior slope. If yes, control may pass to block  736 . If no, control may pass to block  734 . If the current slope is different than the prior slope, this may indicate that a curve was previously generated. In  FIG. 24 , for example, if the current reference point was  754 , the current slope would be different than the prior slope, indicating a curve had been generated. Thus, at block  734 , the current reference point may be shifted in position to the end of the curve in the direction of the next reference point. In  FIG. 24 , for example, if reference point  754  was the current reference point, the position of reference point  754  would be shifted to location  755 . Then, control may pass to block  736 . 
     At block  736 , it may be determined whether the current slope is the same as the next slope. If yes, control may pass to block  738 . At block  738 , two triangles may be generated from the current reference point to the next reference point to form a segment of the payline between the two reference points. In particular, the two triangles may form a segment having the payline width (which may be defined at block  702 ,  FIG. 21 ). Control may then pass to block  744 . 
     If at block  736 , it was determined that the current slope is not the same as the 25 next slope, control may pass to block  740 . 
     At block  740 , a curve in the payline may be formed. For instance, the curve maybe formed using a plurality of triangles. In  FIG. 24 , for example, a curve about reference point  754  is generated with five triangles  768 ,  770 ,  772 ,  774 ,  776 . Parameters for generating the curve may be defined previous to executing block  740 . Such parameters may include, for example, a curve radius, a number of polygons to be included in the curve. Such parameters may be defined, for example, at block  702 , of  FIG. 21 . Any number of techniques for generating curves can be used, including those known to those of ordinary skill in the art of graphics processing. One example of a method for generating a curve will be described subsequently with reference to  FIG. 23 . Then, control may pass to block  742 . 
     At block  742 , two triangles may be generated from the current reference point to the beginning of the curve generated at block  740 , to form a segment of the payline between the two reference points. In particular, the two triangles may form a segment having the payline width (which may be defined at block  702 ,  FIG. 21 ). In  FIG. 24 , for example, the two triangles  760  and  762  form a payline segment from reference point  752  to the beginning of the curve about reference point  754 . Control may then pass to block  744 . 
     At block  744 , the current reference point may be set to the next reference point. In  FIG. 24 , for example, if reference point  752  was the current reference point, the current reference point may be set to reference point  754 . Additionally at block  744 , the prior slope may be set to the current slope. Similarly, the current slope may be set to the next slope. Then, control may pass to block  728 . 
     Although in the embodiment described above, the generated payline is a flat object in 3D model space, other types of paylines may be used. For example, the payline may have a thickness. Similarly, the payline may be cylindrical, have a triangular cross section, a hexagonal cross section, etc. Also, if slopes between different segments in the payline are different, a curve need not be generated (as in block  740 ). Rather, the payline may include “sharp” vertices. 
     Additionally, although in the embodiment described above, the generated payline is located in one plane in 3D model space, the payline could have a different structure. For example, one segment of the payline may lie in a first plane, and a second segment may lie in a second plane different than the first plane. In these embodiments, a location in the payline in which is to be generated may be determined, for example, by examining the direction of lines between reference points, gradients between reference points, etc. Also, the payline, or a portion thereof, may be curved in 3D model space, with a segment not lying in one plane. As a specific example, the payline, or a portion thereof, may have a helical structure. 
     Also, the payline need not reside “in front” of the game display. Referring to  FIG. 20 , for example, the payline generated could extend from the front of reel  672 , to the rear of reel  674 , and then to the front of reel  676 . 
     Curve Generation 
       FIG. 23  is a flow diagram illustrating one embodiment of a method  740  for generating a curve in a payline. Method  740  will be described with reference to  FIG. 24 . At block  788 , a center of the curve radius is determined. The curve radius R may be previously defined, for example, at block  702  of  FIG. 21 . Additionally, the width W of the payline may be previously defined, for example, at block  702  of  FIG. 21 . In one embodiment, the center may be determined by calculating perpendicular distances from lines between the reference points of the payline. In  FIG. 24  for example, the center point  778  may be the point that is a perpendicular distance R-W/ 2  from the line between reference points  752  and  754 , and that also is the perpendicular distance R-W/ 2  from the line between reference points  754  and  756 . 
     At block  790 , a number of vertices on the “outside” of the curve may be determined. In one embodiment, the number of vertices can be determined based on a number of triangles that are to be included in the curve. The number K of triangles may be previously defined, for example, at block  702  of  FIG. 21 . For example, the number of vertices on the outside of the curve may be determined as K/ 2  rounded up to the nearest integer, plus 1. In  FIG. 24 , for example, the number K of triangles is five. Thus, the number of vertices on the outside of the curve is four (5/2 rounded up to 3 plus 1). 
     In other embodiments, the number of vertices may be previously defined, for example, at block  702  of  FIG. 21 . Additionally, the number of vertices may be determined by retrieving the number from a look up table based on the number K of triangles. 
     At block  792 , positions of the vertices on the outside of the curve may be determined. In one embodiment, a position of one vertex is determined as being a distance R from the center point on a line that is perpendicular to a line between the reference point about which the curve is being generated and the previous reference point. For example, in  FIG. 24 , vertex  779  is at a distance R from center point  778  on a line that is perpendicular to the line between reference points  752  and  754 . 
     In this embodiment, a position of another vertex is similarly determined as being a distance R from the center point on a line that is perpendicular to a line between the reference point about which the curve is being generated and the next reference point. For example, in  FIG. 24 , vertex  780  is at a distance R from center point  778  on a line that is perpendicular to the line between reference points  754  and  756 . 
     In this embodiment, positions of the remaining vertices can be determined as being a distance R from the center point, and also being equidistant from other vertices. For example, in  FIG. 24 , vertices  781  and  782  are both a distance R from center point  778 . Additionally, vertex  781  is equidistant between vertices  779  and  782 . Similarly, vertex  782  is equidistant between vertices  780  and  781 . 
     At block  794 , a number of vertices on the “inside” of the curve may be determined. The number of vertices on the inside of the curve may be determined in a manner similar to that described with reference to block  790 . For example, in one embodiment, the number of vertices can be determined based on a number of triangles that are to be included in the curve. The number K of triangles may be previously defined, for example, at block  702  of  FIG. 21 . For example, the number of vertices on the inside of the curve may be determined as K/ 2  rounded down to the nearest integer, plus 1. In  FIG. 24 , for example, the number K of triangles is five. Thus, the number of vertices on the inside of the curve is three (5/2 rounded down to 2 plus 1). 
     At block  796 , positions of the vertices on the “inside” of the curve may be determined. The positions of the vertices on the inside of the curve may be determined in a manner similar to that described with reference to block  792 . For example, in one embodiment, a position of one vertex is determined as being a distance R-W from the center point on a line that is perpendicular to a line between the reference point about which the curve is being generated and the previous reference point. For example, in  FIG. 24 , vertex  783  is at a distance R-W from center point  778  on a line that is perpendicular to the line between reference points  752  and  754 . 
     In this embodiment, a position of another vertex is similarly determined as being a distance R-W from the center point on a line that is perpendicular to a line between the reference point about which the curve is being generated and the next reference point. For example, in  FIG. 24 , vertex  784  is at a distance R-W from center point  778  on a line that is perpendicular to the line between reference points  754  and  756 . 
     In this embodiment, positions of the remaining vertices can be determined as being a distance R-W from the center point, and also being equidistant from other vertices. For example, in  FIG. 24 , vertex  785  is a distance R-W from center point  778 . Additionally, vertex  785  is equidistant between vertices  783  and  784 . 
     At block  798 , triangles of which the curve is to be comprised are determined based on the vertices determined at blocks  792  and  796 . For example, in  FIG. 24 , the triangles  768 ,  770 ,  772 ,  774 , and  776  are determined based on the vertices  779 ,  780 ,  781 ,  782 ,  783 ,  784 , and  785 . 
     In other embodiments, the payline may be generated, for example, by retrieving polygon information (e.g., coordinates of vertices, polygon types, etc.) from a memory or look-up-table. In these embodiments, reference points of the payline may not be needed. Also, the methods described with reference to  FIGS. 22 and 23  may not be needed. For instance, if a game includes five possible paylines, the five paylines could be designated, for example, by the numbers 1-5. Then, if it was desired to generate payline  1 , polygon information for generating that payline could be retrieved from a look-up table. 
     Transparent Objects 
       FIGS. 25A and 25B  illustrate an example of a game display and a transparent object in 3D model space. In particular, the 3D model  800  includes a plane  802  having a game display  804  mapped thereon. As merely one example, game display  804  may include an image (or images) of slot reels. Additionally, the 3D model includes a transparent object  806 . The transparent object  806  can be, for example, an icon, a button, a menu, a window (e.g., gaff window, help window, tilt window, other informational windows such as a “You Won!” window, a “Printing Ticket” window, etc.), a screen display (e.g., a gaff screen, a help screen, a tilt screen, other informational screens such as a “You Won!” screen, a “Printing Ticket” screen, etc.), etc.  FIG. 25B  is a side view of the 3D model  800  showing that the transparent object  806  is between the plane  802  having the game display  804 , and a point of view  808 . 
     During a game, the game display  804  may include the image (or images) of a game being played, such as reels of a slot machine, a hand of cards, etc. The transparent object  806  may be rendered during the play of a game. For example, if a “tilt” condition occurred, a “tilt window”  806  could be rendered. Because the object  806  is transparent, aspects of the game display  804  may be visible despite being “behind” the object  806 . 
     It is to be understood that the game display  804  need not be a flat 2D object on a plane  802 . Rather, the game display could be a 3D object. For example, the game display could be a 3D object such as the virtual slot machine game illustrated in  FIG. 20 . 
       FIG. 26  is a flow diagram illustrating one embodiment of a method  820  for displaying a transparent object, such as a window, icon, etc., on a game display. The method  820  will be described with reference to  FIGS. 3 ,  6 A,  6 B,  25 A, and  25 B. At block  822 , the object may be generated in 3D space. Generating the object in 3D space may include generating the 3D primitive information of one or more polygons that comprise the object. In  FIG. 25A , for example, the object  806  may comprise one quadrilateral, two or more triangles, etc. 
     At block  824 , graphics attributes are associated with the object, the graphics attributes including transparency information. The transparency information may include information such as one or more alpha values, one or more flags indicating the object is transparent, etc. Other attributes may include, for example, color, texture, texture mapping, etc. Additionally, using graphics attributes, the object can be made to appear to oscillate, move, rotate, pivot, or slide on the screen. Similarly, the object may appear to be on fire, be drawn by a laser, or the object&#39;s colors may appear to change. 
     At block  826 , the transparent object may be displayed “over” the game display. If a graphics processor such as the graphics processor  107 B of  FIG. 6B  is used, displaying the object may include providing the 3D primitive information generated at block  822  to the graphics processor  107 . This may also include providing the effects information associated with the object (block  824 ) to the graphics processor  107 . If a graphics processor such at the graphics processor  107 A of  FIG. 6A  is used, displaying the object may include the microprocessor  104  performing “Transform and Lighting” processing on the 3D primitive information generated at block  822  to generate 2D primitive information. Then, the 2D primitive information may be provided to graphics processor  107 . Next, the graphics processor  107  may generates one or more control signals that control display unit  70  to display an image of the object such that it appears to be transparent. 
     In some embodiments, the graphics processor  107  may combine the color information of the object with the color information of the image “behind” the object such that the object appears transparent. Any number of techniques may be used to combine the color information of the object with that of the underlying image, including techniques known to those of ordinary skill in the art. Such known techniques include “alpha blending,” “screen-door” techniques, filtered transparency techniques, etc. 
     As described with reference to  FIGS. 6A and 6B , in some embodiments, graphics processor  107  may include an external overlay input with an ability to configure the external overlay as transparent.  FIG. 27  is flow diagram of an embodiment of a method  850  for generating a transparent object with such graphics processors. At block  852 , a bitmap of the object as it is to be displayed on the display unit (except for its transparency) is generated. The bitmap may be generated when needed, generated ahead of time and stored in a memory, etc. 
     At block  854 , the bitmap may be provided to the graphics processor  107 . The bitmap may be provided to graphics processor  107  via its external overlay input (if included), a shared input or input/output interface, etc. At block  856 , the graphics processor is instructed to display the bitmap as a transparent overlay. This may include indicating the location at which the bitmap is to be displayed on a screen, a degree of transparency, etc. 
     The above examples describe a single transparent object. It will be apparent to those of ordinary skill in the art, however, that there may be multiple transparent objects as well (e.g., 2, 3, 4, etc.). In these embodiments, two or more of the transparent objects may overlap when viewed from the viewpoint. In these embodiments, the color information from the game display and multiple transparent objects may be combined. 
     In the above description, various methods have been described with reference to flow diagrams. It will be apparent to one of ordinary skill in the art that each of these methods may be implemented, in whole or in part, by software, hardware, and/or firmware. If implemented, in whole or in part, by software, the software may be stored on a tangible medium such as a CD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), a read-only memory (ROM), etc. Further, although the examples described above were described with reference to various flow diagrams, one of ordinary skill in the art will appreciate that many other methods may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some or all of the blocks may be changed, eliminated, or combined.