Patent ID: 12229869

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth to provide a more thorough understanding of the various embodiments. However, it will be apparent to one skilled in the art that the inventive concepts may be practiced without one or more of these specific details.

General Overview

Embodiments of the present disclosure provide improved ray cone tracing techniques that implement refracted ray cones. The improved ray cone tracing techniques have many real-world applications, including video games, film production rendering, architectural and design applications, and any other applications in which images can be rendered using ray cone tracing. In the improved ray cone tracing techniques, when a ray cone being traced through a virtual three-dimensional (3D) scene hits a surface of geometry within the scene and undergoes refraction, a refracted ray cone is generated by (1) computing, in a two-dimensional (2D) coordinate frame, the direction of a middle ray of the refracted ray cone and the directions of upper and lower sides of the refracted ray cone; and (2) given such computations, further computing a width of the refracted ray cone and a spread angle of the refracted cone. The refracted ray cone is then traced through the scene. In addition, isotropic texture filtering can be performed prior to generating the refracted ray cone, and anisotropic texture filtering can be performed using the refracted ray cone and any subsequent ray cones, to determine the color of a pixel in a rendered image.

The ray cone tracing techniques of the present disclosure have many real-world applications. For example, the ray cone tracing techniques can be used to efficiently render images and/or frames within a video game. As a particular example, the ray cone tracing techniques could be performed by a cloud-based graphics processing platform, such as a cloud-based gaming platform, that executes video games and streams videos of game sessions to client devices. The disclosed ray cone tracing techniques are more computationally efficient and/or can render more realistic images than some other techniques, such as differential ray tracing techniques, conventional ray cone tracing techniques, and rasterization-based techniques.

As another example, the ray cone tracing techniques can be used in the production-quality rendering of films. The production of animated films as well computer-generated imagery (CGI) and special effects within live action films, often requires high-quality rendering of frames of those films. The disclosed ray cone tracing techniques can be used to render the frames of a film more efficiently and/or correctly than some other techniques, such as differential ray tracing techniques and conventional ray cone tracing techniques.

As yet another example, the disclosed ray cone tracing techniques can be used to render the designs of architectural structures and other objects. Architectural and design applications oftentimes provide renderings to show the appearances of particular designs in real life. The disclosed ray cone tracing techniques can be used to more efficiently and/or correctly render images of designs than some other techniques, such as differential ray tracing techniques and conventional ray cone tracing techniques.

The above examples are not in any way intended to be limiting. As persons skilled in the art will appreciate, as a general matter, the ray cone tracing techniques described herein can be implemented in any application where convention ray tracing and/or ray cone tracing techniques are currently employed.

System Overview

FIG.1is a block diagram illustrating a computer system100configured to implement one or more aspects of the present embodiments. As persons skilled in the art will appreciate, computer system100can be any type of technically feasible computer system, including, without limitation, a server machine, a server platform, a desktop machine, laptop machine, a hand-held/mobile device, or a wearable device. In some embodiments, computer system100is a server machine operating in a data center or a cloud computing environment that provides scalable computing resources as a service over a network.

In various embodiments, computer system100includes, without limitation, a central processing unit (CPU)102and a system memory104coupled to a parallel processing subsystem112via a memory bridge105and a communication path113. Memory bridge105is further coupled to an I/O (input/output) bridge107via a communication path106, and I/O bridge107is, in turn, coupled to a switch116.

In one embodiment, I/O bridge107is configured to receive user input information from optional input devices108, such as a keyboard or a mouse, and forward the input information to CPU102for processing via communication path106and memory bridge105. In some embodiments, computer system100may be a server machine in a cloud computing environment. In such embodiments, computer system100may not have input devices108. Instead, computer system100may receive equivalent input information by receiving commands in the form of messages transmitted over a network and received via the network adapter118. In one embodiment, switch116is configured to provide connections between I/O bridge107and other components of the computer system100, such as a network adapter118and various add-in cards120and121.

In one embodiment, I/O bridge107is coupled to a system disk114that may be configured to store content and applications and data for use by CPU102and parallel processing subsystem112. In one embodiment, system disk114provides non-volatile storage for applications and data and may include fixed or removable hard disk drives, flash memory devices, and CD-ROM (compact disc read-only-memory), DVD-ROM (digital versatile disc-ROM), Blu-ray, HD-DVD (high definition DVD), or other magnetic, optical, or solid state storage devices. In various embodiments, other components, such as universal serial bus or other port connections, compact disc drives, digital versatile disc drives, film recording devices, and the like, may be connected to I/O bridge107as well.

In various embodiments, memory bridge105may be a Northbridge chip, and I/O bridge107may be a Southbridge chip. In addition, communication paths106and113, as well as other communication paths within computer system100, may be implemented using any technically suitable protocols, including, without limitation, AGP (Accelerated Graphics Port), HyperTransport, or any other bus or point-to-point communication protocol known in the art.

In some embodiments, parallel processing subsystem112comprises a graphics subsystem that delivers pixels to an optional display device110that may be any conventional cathode ray tube, liquid crystal display, light-emitting diode display, or the like. In such embodiments, the parallel processing subsystem112incorporates circuitry optimized for graphics and video processing, including, for example, video output circuitry. As described in greater detail below in conjunction withFIGS.2-3, such circuitry may be incorporated across one or more parallel processing units (PPUs), also referred to herein as parallel processors, included within parallel processing subsystem112. In other embodiments, the parallel processing subsystem112incorporates circuitry optimized for general purpose and/or compute processing. Again, such circuitry may be incorporated across one or more PPUs included within parallel processing subsystem112that are configured to perform such general purpose and/or compute operations. In yet other embodiments, the one or more PPUs included within parallel processing subsystem112may be configured to perform graphics processing, general purpose processing, and compute processing operations. System memory104includes at least one device driver configured to manage the processing operations of the one or more PPUs within parallel processing subsystem112. In addition, the system memory104includes a rendering application130. The rendering application130can be any technically-feasible application that renders virtual 3D scenes via ray cone tracing techniques disclosed herein. For example, the rendering application130could be a gaming application or a rendering application that is used in film production. Although described herein primarily with respect to the rendering application130, techniques disclosed herein can also be implemented, either entirely or in part, in other software and/or hardware, such as in the parallel processing subsystem112.

In various embodiments, parallel processing subsystem112may be integrated with one or more of the other elements ofFIG.1to form a single system. For example, parallel processing subsystem112may be integrated with CPU102and other connection circuitry on a single chip to form a system on chip (SoC).

In one embodiment, CPU102is the master processor of computer system100, controlling and coordinating operations of other system components. In one embodiment, CPU102issues commands that control the operation of PPUs. In some embodiments, communication path113is a PCI Express link, in which dedicated lanes are allocated to each PPU, as is known in the art. Other communication paths may also be used. PPU advantageously implements a highly parallel processing architecture. A PPU may be provided with any amount of local parallel processing memory (PP memory).

It will be appreciated that the system shown herein is illustrative and that variations and modifications are possible. The connection topology, including the number and arrangement of bridges, the number of CPUs102, and the number of parallel processing subsystems112, may be modified as desired. For example, in some embodiments, system memory104could be connected to CPU102directly rather than through memory bridge105, and other devices would communicate with system memory104via memory bridge105and CPU102. In other embodiments, parallel processing subsystem112may be connected to I/O bridge107or directly to CPU102, rather than to memory bridge105. In still other embodiments, I/O bridge107and memory bridge105may be integrated into a single chip instead of existing as one or more discrete devices. In certain embodiments, one or more components shown inFIG.1may not be present. For example, switch116could be eliminated, and network adapter118and add-in cards120,121would connect directly to I/O bridge107. Lastly, in certain embodiments, one or more components shown inFIG.1may be implemented as virtualized resources in a virtual computing environment, such as a cloud computing environment. In particular, the parallel processing subsystem112may be implemented as a virtualized parallel processing subsystem in some embodiments. For example, the parallel processing subsystem112could be implemented as a virtual graphics processing unit (GPU) that renders graphics on a virtual machine (VM) executing on a server machine whose GPU and other physical resources are shared across multiple VMs.

FIG.2is a block diagram of a parallel processing unit (PPU)202included in the parallel processing subsystem112ofFIG.1, according to various embodiments. AlthoughFIG.2depicts one PPU202, as indicated above, parallel processing subsystem112may include any number of PPUs202. As shown, PPU202is coupled to a local parallel processing (PP) memory204. PPU202and PP memory204may be implemented using one or more integrated circuit devices, such as programmable processors, application specific integrated circuits (ASICs), or memory devices, or in any other technically feasible fashion.

In some embodiments, PPU202comprises a GPU that may be configured to implement a graphics rendering pipeline to perform various operations related to generating pixel data based on graphics data supplied by CPU102and/or system memory104. When processing graphics data, PP memory204can be used as graphics memory that stores one or more conventional frame buffers and, if needed, one or more other render targets as well. Among other things, PP memory204may be used to store and update pixel data and deliver final pixel data or display frames to an optional display device110for display. In some embodiments, PPU202also may be configured for general-purpose processing and compute operations. In some embodiments, computer system100may be a server machine in a cloud computing environment. In such embodiments, computer system100may not have a display device110. Instead, computer system100may generate equivalent output information by transmitting commands in the form of messages over a network via the network adapter118.

In some embodiments, CPU102is the master processor of computer system100, controlling and coordinating operations of other system components. In one embodiment, CPU102issues commands that control the operation of PPU202. In some embodiments, CPU102writes a stream of commands for PPU202to a data structure (not explicitly shown in eitherFIG.1orFIG.2) that may be located in system memory104, PP memory204, or another storage location accessible to both CPU102and PPU202. A pointer to the data structure is written to a command queue, also referred to herein as a pushbuffer, to initiate processing of the stream of commands in the data structure. In one embodiment, the PPU202reads command streams from the command queue and then executes commands asynchronously relative to the operation of CPU102. In embodiments where multiple pushbuffers are generated, execution priorities may be specified for each pushbuffer by an application program via device driver to control scheduling of the different pushbuffers.

In one embodiment, PPU202includes an I/O (input/output) unit205that communicates with the rest of computer system100via the communication path113and memory bridge105. In one embodiment, I/O unit205generates packets (or other signals) for transmission on communication path113and also receives all incoming packets (or other signals) from communication path113, directing the incoming packets to appropriate components of PPU202. For example, commands related to processing tasks may be directed to a host interface206, while commands related to memory operations (e.g., reading from or writing to PP memory204) may be directed to a crossbar unit210. In one embodiment, host interface206reads each command queue and transmits the command stream stored in the command queue to a front end212.

As mentioned above in conjunction withFIG.1, the connection of PPU202to the rest of computer system100may be varied. In some embodiments, parallel processing subsystem112, which includes at least one PPU202, is implemented as an add-in card that can be inserted into an expansion slot of computer system100. In other embodiments, PPU202can be integrated on a single chip with a bus bridge, such as memory bridge105or I/O bridge107. Again, in still other embodiments, some or all of the elements of PPU202may be included along with CPU102in a single integrated circuit or system of chip (SoC).

In one embodiment, front end212transmits processing tasks received from host interface206to a work distribution unit (not shown) within task/work unit207. In one embodiment, the work distribution unit receives pointers to processing tasks that are encoded as task metadata (TMD) and stored in memory. The pointers to TMDs are included in a command stream that is stored as a command queue and received by the front end unit212from the host interface206. Processing tasks that may be encoded as TMDs include indices associated with the data to be processed as well as state parameters and commands that define how the data is to be processed. For example, the state parameters and commands could define the program to be executed on the data. Also, for example, the TMD could specify the number and configuration of the set of CTAs. Generally, each TMD corresponds to one task. The task/work unit207receives tasks from the front end212and ensures that GPCs208are configured to a valid state before the processing task specified by each one of the TMDs is initiated. A priority may be specified for each TMD that is used to schedule the execution of the processing task. Processing tasks also may be received from the processing cluster array230. Optionally, the TMD may include a parameter that controls whether the TMD is added to the head or the tail of a list of processing tasks (or to a list of pointers to the processing tasks), thereby providing another level of control over execution priority.

In one embodiment, PPU202implements a highly parallel processing architecture based on a processing cluster array230that includes a set of C general processing clusters (GPCs)208, where C≥1. Each GPC208is capable of executing a large number (e.g., hundreds or thousands) of threads concurrently, where each thread is an instance of a program. In various applications, different GPCs208may be allocated for processing different types of programs or for performing different types of computations. The allocation of GPCs208may vary depending on the workload arising for each type of program or computation.

In one embodiment, memory interface214includes a set of D of partition units215, where D≥1. Each partition unit215is coupled to one or more dynamic random access memories (DRAMs)220residing within PPM memory204. In some embodiments, the number of partition units215equals the number of DRAMs220, and each partition unit215is coupled to a different DRAM220. In other embodiments, the number of partition units215may be different than the number of DRAMs220. Persons of ordinary skill in the art will appreciate that a DRAM220may be replaced with any other technically suitable storage device. In operation, various render targets, such as texture maps and frame buffers, may be stored across DRAMs220, allowing partition units215to write portions of each render target in parallel to efficiently use the available bandwidth of PP memory204.

In one embodiment, a given GPC208may process data to be written to any of the DRAMs220within PP memory204. In one embodiment, crossbar unit210is configured to route the output of each GPC208to the input of any partition unit215or to any other GPC208for further processing. GPCs208communicate with memory interface214via crossbar unit210to read from or write to various DRAMs220. In some embodiments, crossbar unit210has a connection to I/O unit205, in addition to a connection to PP memory204via memory interface214, thereby enabling the processing cores within the different GPCs208to communicate with system memory104or other memory not local to PPU202. In the embodiment ofFIG.2, crossbar unit210is directly connected with I/O unit205. In various embodiments, crossbar unit210may use virtual channels to separate traffic streams between the GPCs208and partition units215.

In one embodiment, GPCs208can be programmed to execute processing tasks relating to a wide variety of applications, including, without limitation, linear and nonlinear data transforms, filtering of video and/or audio data, modeling operations (e.g., applying laws of physics to determine position, velocity and other attributes of objects), image rendering operations (e.g., tessellation shader, vertex shader, geometry shader, and/or pixel/fragment shader programs), general compute operations, etc. In operation, PPU202is configured to transfer data from system memory104and/or PP memory204to one or more on-chip memory units, process the data, and write result data back to system memory104and/or PP memory204. The result data may then be accessed by other system components, including CPU102, another PPU202within parallel processing subsystem112, or another parallel processing subsystem112within computer system100.

In one embodiment, any number of PPUs202may be included in a parallel processing subsystem112. For example, multiple PPUs202may be provided on a single add-in card, or multiple add-in cards may be connected to communication path113, or one or more of PPUs202may be integrated into a bridge chip. PPUs202in a multi-PPU system may be identical to or different from one another. For example, different PPUs202might have different numbers of processing cores and/or different amounts of PP memory204. In implementations where multiple PPUs202are present, those PPUs may be operated in parallel to process data at a higher throughput than is possible with a single PPU202. Systems incorporating one or more PPUs202may be implemented in a variety of configurations and form factors, including, without limitation, desktops, laptops, handheld personal computers or other handheld devices, wearable devices, servers, workstations, game consoles, embedded systems, and the like.

FIG.3is a block diagram of a general processing cluster (GPC)208included in the parallel processing unit (PPU)202ofFIG.2, according to various embodiments. As shown, the GPC208includes, without limitation, a pipeline manager305, one or more texture units315, a preROP unit325, a work distribution crossbar330, and an L1.5 cache335.

In one embodiment, GPC208may be configured to execute a large number of threads in parallel to perform graphics, general processing and/or compute operations. As used herein, a “thread” refers to an instance of a particular program executing on a particular set of input data. In some embodiments, single-instruction, multiple-data (SIMD) instruction issue techniques are used to support parallel execution of a large number of threads without providing multiple independent instruction units. In other embodiments, single-instruction, multiple-thread (SIMT) techniques are used to support parallel execution of a large number of generally synchronized threads, using a common instruction unit configured to issue instructions to a set of processing engines within GPC208. Unlike a SIMD execution regime, where all processing engines typically execute identical instructions, SIMT execution allows different threads to more readily follow divergent execution paths through a given program. Persons of ordinary skill in the art will understand that a SIMD processing regime represents a functional subset of a SIMT processing regime.

In one embodiment, operation of GPC208is controlled via a pipeline manager305that distributes processing tasks received from a work distribution unit (not shown) within task/work unit207to one or more streaming multiprocessors (SMs)310. Pipeline manager305may also be configured to control a work distribution crossbar330by specifying destinations for processed data output by SMs310.

In various embodiments, GPC208includes a set of M of SMs310, where M≥1. Also, each SM310includes a set of functional execution units (not shown), such as execution units and load-store units. Processing operations specific to any of the functional execution units may be pipelined, which enables a new instruction to be issued for execution before a previous instruction has completed execution. Any combination of functional execution units within a given SM310may be provided. In various embodiments, the functional execution units may be configured to support a variety of different operations including integer and floating point arithmetic (e.g., addition and multiplication), comparison operations, Boolean operations (AND, OR, 5OR), bit-shifting, and computation of various algebraic functions (e.g., planar interpolation and trigonometric, exponential, and logarithmic functions, etc.). Advantageously, the same functional execution unit can be configured to perform different operations.

In one embodiment, each SM310is configured to process one or more thread groups. As used herein, a “thread group” or “warp” refers to a group of threads concurrently executing the same program on different input data, with one thread of the group being assigned to a different execution unit within an SM310. A thread group may include fewer threads than the number of execution units within the SM310, in which case some of the execution may be idle during cycles when that thread group is being processed. A thread group may also include more threads than the number of execution units within the SM310, in which case processing may occur over consecutive clock cycles. Since each SM310can support up to G thread groups concurrently, it follows that up to G*M thread groups can be executing in GPC208at any given time.

Additionally, in one embodiment, a plurality of related thread groups may be active (in different phases of execution) at the same time within an SM310. This collection of thread groups is referred to herein as a “cooperative thread array” (“CTA”) or “thread array.” The size of a particular CTA is equal to m*k, where k is the number of concurrently executing threads in a thread group, which is typically an integer multiple of the number of execution units within the SM310, and m is the number of thread groups simultaneously active within the SM310. In some embodiments, a single SM310may simultaneously support multiple CTAs, where such CTAs are at the granularity at which work is distributed to the SMs310.

In one embodiment, each SM310contains a level one (L1) cache or uses space in a corresponding L1 cache outside of the SM310to support, among other things, load and store operations performed by the execution units. Each SM310also has access to level two (L2) caches (not shown) that are shared among all GPCs208in PPU202. The L2 caches may be used to transfer data between threads. Finally, SMs310also have access to off-chip “global” memory, which may include PP memory204and/or system memory104. It is to be understood that any memory external to PPU202may be used as global memory. Additionally, as shown inFIG.3, a level one-point-five (L1.5) cache335may be included within GPC208and configured to receive and hold data requested from memory via memory interface214by SM310. Such data may include, without limitation, instructions, uniform data, and constant data. In embodiments having multiple SMs310within GPC208, the SMs310may beneficially share common instructions and data cached in L1.5 cache335.

In one embodiment, each GPC208may have an associated memory management unit (MMU)320that is configured to map virtual addresses into physical addresses. In various embodiments, MMU320may reside either within GPC208or within the memory interface214. The MMU320includes a set of page table entries (PTEs) used to map a virtual address to a physical address of a tile or memory page and optionally a cache line index. The MMU320may include address translation lookaside buffers (TLB) or caches that may reside within SMs310, within one or more L1 caches, or within GPC208.

In one embodiment, in graphics and compute applications, GPC208may be configured such that each SM310is coupled to a texture unit315for performing texture mapping operations, such as determining texture sample positions, reading texture data, and filtering texture data.

In one embodiment, each SM310transmits a processed task to work distribution crossbar330in order to provide the processed task to another GPC208for further processing or to store the processed task in an L2 cache (not shown), parallel processing memory204, or system memory104via crossbar unit210. In addition, a pre-raster operations (preROP) unit325is configured to receive data from SM310, direct data to one or more raster operations (ROP) units within partition units215, perform optimizations for color blending, organize pixel color data, and perform address translations.

It will be appreciated that the architecture described herein is illustrative and that variations and modifications are possible. Among other things, any number of processing units, such as SMs310, texture units315, or preROP units325, may be included within GPC208. Further, as described above in conjunction withFIG.2, PPU202may include any number of GPCs208that are configured to be functionally similar to one another so that execution behavior does not depend on which GPC208receives a particular processing task. Further, each GPC208operates independently of the other GPCs208in PPU202to execute tasks for one or more application programs.

FIG.4is a block diagram illustrating an exemplar cloud computing system, according to various embodiments. As shown, a computing system400includes server(s)402that are in communication with client device(s)404via network(s)406. Each of the server(s)402may include similar components, features, and/or functionality as the exemplary computer system100, described above in conjunction withFIG.1-3. Each of the server(s)402may be any technically feasible type of computer system, including, without limitation, a server machine or a server platform. Each of the client devices(s)402may also include similar components, features, and/or functionality as the computer system100, except each client device402executes a client application422rather than the rendering application130. Each of the client device(s)402may be any technically feasible type of computer system including, without limitation, a desktop machine, a laptop machine, a hand-held/mobile device, and/or a wearable device. In some embodiments, one or more of the server(s)402and/or the client device(s)404may be replaced with virtualized processing environment(s), such as virtualized processing environment(s) provided by one or more VMs and/or containers that execute on underlying hardware system(s). The network(s)406may include any type of network(s), such as one or more local area networks (LANs) and/or wide area networks (WANs) (e.g., the Internet).

In some embodiments, the server(s)400may be included in a cloud computing system, such a public cloud, a private cloud, or a hybrid cloud, and/or in a distributed system. For example, the server(s)400could implement a cloud-based gaming platform that provides a game streaming service, also sometimes referred to as “cloud gaming,” “gaming on demand,” or “gaming-as-a-service.” In such a case, games that are stored and executed on the server(s)400are streamed as videos to the client device(s)402via client application(s)422running thereon. During game sessions, the client application(s)422handle user inputs and transmit those inputs to the server(s)400for in-game execution. Although cloud-based gaming platforms are described herein as a reference example, persons skilled in the art will appreciate that, as a general matter, the server(s)400may execute any technically feasible types of application(s), such as the design applications described above.

As shown, each of the client device(s)404includes input device(s)426, the client application422, a communication interface420, and a display424. The input device(s)426may include any type of device(s) for receiving user input, such as a keyboard, a mouse, a joystick, and/or a game controller. The client application422receives input data in response to user inputs at the input device(s)426, transmits the input data to one of the server(s)402via the communication interface420(e.g., a network interface controller) and over the network(s)406(e.g., the Internet), receives encoded display data from the server402, and decodes and causes the display data to be displayed on the display424(e.g., a cathode ray tube, liquid crystal display, light-emitting diode display, or the like). As such, more computationally intense computing and processing can be offloaded to the server(s)402. For example, a game session could be streamed to the client device(s)404from the server(s)402, thereby reducing the requirements of the client device(s)404for graphics processing and rendering.

As shown, each of the server(s)402includes a communication interface418, CPU(s)408, a parallel processing subsystem410, a rendering component412, a render capture component414, and an encoder416. Input data transmitted by the client device404to one of the server(s)402is received via the communication interface418(e.g., a network interface controller) and processed via the CPU(s)408and/or the parallel processing subsystem410included in that server402, which correspond to the CPU102and the parallel processing subsystem112, respectively, of the computer system100described above in conjunction withFIGS.1-3. In some embodiments, the CPU(s)408may receive the input data, process the input data, and transmit data to the parallel processing subsystem410. In turn, the parallel processing subsystem410renders one or more standalone images and/or image frames, such as the frames of a video game, based on the transmitted data.

Illustratively, the rendering component412employs the parallel processing subsystem112to render the result of processing the input data, and the render capture component414captures the rendering as display data (e.g., as image data capturing standalone image(s) and/or image frame(s)). The rendering performed by the rendering component412may include ray- or path-traced lighting and/or shadow effects, computed using one or more parallel processing units—such as GPUs, which may further employ the use of one or more dedicated hardware accelerators or processing cores to perform ray or path-tracing techniques—of the server402. In some embodiments, the rendering component412performs rendering using the ray cone tracing techniques disclosed herein. Thereafter, the encoder416encodes display data capturing the rendering to generate encoded display data that is transmitted, over the network(s)406via the communication interface418, to the client device(s)422for display to user(s). In some embodiments, the rendering component412, the render capture component414, and the encoder416may be included in the rendering application130, described above in conjunction withFIG.1.

Returning to the example of cloud gaming, during a game session, input data that is received by one of the server(s)402may be representative of movement of a character of the user in a game, firing a weapon, reloading, passing a ball, turning a vehicle, etc. In such a case, the rendering component412may generate a rendering of the game session that is representative of the result of the input data, and the render capture component414may capture the rendering of the game session as display data (e.g., as image data capturing rendered frames of the game session). Parallel processing (e.g., GPU) resources may be dedicated to each game session, or resource scheduling techniques may be employed to share parallel processing resources across multiple game sessions. In addition, the game session may be rendered using the ray cone tracing techniques disclosed herein. The rendered game session may then be encoded, by the encoder416, to generate encoded display data that is transmitted over the network(s)406to one of the client device(s)404for decoding and output via the display424of that client device404.

It will be appreciated that the architecture described herein is illustrative and that variations and modifications are possible. Among other things, any number of processing units, such as the SMs310, texture units315, or preROP units325, described above in conjunction withFIG.3, may be included within GPC208.

Texture Filtering Using Refracted Ray Cones

FIG.5illustrates an exemplar ray cone being traced through a virtual three-dimensional scene, according to various embodiments. As shown, a ray cone500, which is an augmentation to a ray502, is traced through a pixel (not shown) in a screen space into a scene that includes two objects510and540. When the ray cone500hits an object at a hit point, the ray cone500can reflect or refract depending on material properties of the object and a surface curvature at the hit point.

As shown, the object510is constructed from a medium that refracts the ray cone500that is incident on the object510, and the object540is constructed from a medium that does not reflect or refract a ray cone530. For example, the object510could be constructed from glass, and the object540could be constructed from concrete.

Illustratively, the rendering application130traces the ray cone500to a hit point506on the object510and performs a texture filtering lookup based on a texture footprint associated with the ray cone500and a texture of a surface of the object510. In some embodiments, performing the texture filtering lookup includes instructing a texture unit of a GPU (e.g., the texture unit315described above in conjunction withFIG.3) to perform texture filtering at the hit point506based on the texture of the object510at the hit point506and a texture footprint corresponding to a size of the ray cone500at that hit point506. For example, the intersection of the ray cone500with a triangle plane, which is the plane passing through vertices of a triangle at the hit point506, forms an ellipse that could be used as a texture footprint during texture filtering. In particular, the rendering application130could input the major and minor axes of such an ellipse into a hardware-accelerated texture lookup unit of a GPU that performs texture filtering based on those axes. Although described herein primarily with respect to texture filtering, in some cases, textures may be sampled without performing texture filtering. For example, when the very first hit of a ray cone along a path is refractive, no texture filtering could be performed prior to the refraction.

After performing the texture filtering lookup (or texture sampling), the rendering application130generates and traces a refracted ray cone520to a hit point524on another side of the object510. It should be noted that generating a refracted ray cone is different from generating a reflected ray cone, because the indices of refraction are typically different for two media on opposing sides of a hit point surface in the case of refraction, whereas the indices of refraction are typically the same in the case of reflection. In the case of refraction, the relative index of refraction, η, of the two media can impact the direction of a refracted ray, which can change not only the width of a refracted ray cone, but also a geometry of the refracted ray cone. Depending on the relative index of refraction (whether a ray refracts from an optically denser to an optically thinner medium, or vice versa), the refracted ray cone can either shrink or grow. In addition, the centerline of a refracted ray cone can generally differ from the direction of a refracted ray generated by refracting a middle ray of an incident ray cone. However, as described in greater detail below, some embodiments do not alter the refracted ray to reflect such a change, because doing so would be more computationally expensive and could miss geometry that would be hit under certain angles.

In some embodiments, the rendering application130generates the refracted ray cone520by computing, in a 2D coordinate frame, the direction of a middle ray of the refracted ray cone520and the directions of upper and lower sides of the refracted ray cone520, and given such computations, further computing a width and a spread angle of the refracted cone520, as described below in conjunction withFIGS.6-11. After tracing the refracted ray cone520to the hit point524, the rendering application130performs another texture filtering lookup based on a texture footprint associated with the refracted ray cone520and a texture of the surface of the object512. In some embodiments, isotropic texture filtering is performed prior to refractions, and anisotropic texture filtering is performed after refractions, such as when the refracted ray cone520hits the other side of the object510at the hit point524. Anisotropic texture filtering, which is more computationally expensive than isotropic texture filtering, can be used to correct imperfections in the reflected ray cone520, as described below in conjunction withFIG.7. In other embodiments, only isotropic texture filtering may be performed.

As shown, the rendering application130generates and traces another refracted ray cone530to a hit point534on the object540. The refracted ray cone530can be generated in a similar manner as the refracted ray cone520. Then, the rendering application130performs another texture filtering lookup based on a texture footprint associated with the refracted ray cone530and a texture of the surface of the object540. Similar to the description above, anisotropic texture filtering can be performed in some embodiments.

Results of the texture filtering lookups, described above, can be used to render, on the surface of the object510, a combination of the textures associated with the surface of the object510at the hit points506and524and the texture associated with the surface of the object540at the hit point534.

FIG.6illustrates an approach for computing refracted ray cones, according to various embodiments. As shown, a ray cone600can be defined by an origin602, denoted by O; an initial width, denoted by w; a spread angle, denoted by α1, that indicates how wide the ray cone600grows as a middle ray603of the ray cone600traverses a scene; and a direction vector604, denoted by d, that indicates a direction of the middle ray603. Illustratively, the ray cone600hits an object610having a curved surface at a hit point616, denoted by P. The ray cone600is then refracted as a refracted ray cone634.

In some embodiments, the rendering application130generates the refracted ray cone634by first computing, in a 2D coordinate frame, (1) a direction vector630, denoted by t, that indicates the direction of a middle ray of the refracted ray cone634; (2) an upper direction vector632, denoted by tu, that is associated with one side of the refracted ray cone634in 2D; and (3) a lower direction vector628, denoted by tl, that is associated with another side of the refracted ray cone634in 2D. The rendering application130then computes a width of the refracted ray cone634based on distances from the hit point616, P, to lines631and629defined by the upper direction vector632, tu, and the lower direction vector628, tl, respectively, along a direction orthogonal to the direction vector630, t. In addition, the rendering application130can compute a half cone angle, denoted by α2, of the refracted ray cone634based on the upper direction vector632, tu, and the lower direction vector628, tl.

More formally, the curvature of the surface610at the hit point616, P, can be modeled as a signed angle, denoted by β, that is positive if the surface610is convex at the hit point616, P, and negative if the surface is concave at the hit point616, P. A rotated normal vector622, denoted by nl, at a point618, denoted by Pl, and a rotated normal vector626, denoted by nu, at another hit point620, denoted by Pu, can then be obtained by rotating, in opposite directions by the angle β, a vector624, denoted by n, that is normal to the surface of the object at the hit point616, P. As described, computations to generate the refracted ray cone634, including determining the rotated normal vectors622, nl, and626, nu, can be performed in two dimensions. In some embodiments, a 2D coordinate frame is defined using the hit point616, P, as an origin of the 2D coordinate frame, a direction of the vector624, n, that is normal to the surface of the object610as a y-axis, and a direction of a tangent vector614, denoted by m, that is orthogonal to the normal vector624, n, and parallel to the direction vector604, d (along a plane of the drawing). In some embodiments, the tangent vector614, m, can be computed using a projection and normalization, as follows:

m=d-(n·d)⁢nd-(n·d)⁢n.(1)
Together, the normal vector624, n, and the tangent vector614, m, form the basis vectors of a plane. The following discussion assumes that all vectors and points are in the 2D coordinate frame described above.

In some embodiments, the upper direction vector608, du, is obtained by rotating the direction vector604, d, associated with the middle ray603of the ray cone600by the spread angle +α of the ray cone600. Similarly, the lower direction vector606, dlcan be obtained by rotating the direction vector604, d, by minus the spread angle −α. As shown, an upper ray607that is associated with one side of the ray cone600has a direction indicated by the upper direction vector608, du, and the upper ray605starts from the origin602, O, offset by half the initial width w/2 in a direction orthogonal to the direction vector604, d. Similarly, a lower ray605that is associated with another side of the ray cone600has a direction indicated by the lower direction vector606, dl, and the lower ray605starts from the origin602, O, offset by half the initial width w/2 in an opposite direction from the upper direction vector608, du, that is orthogonal to the direction vector604, d. The upper and lower rays607and605are traced through the scene, until the upper and lower rays607and605intersect with the x-axis of the 2D coordinate frame at point Puand Pl, respectively.

Given the direction vector604, d, associated with the incident ray, the rendering application130determines whether refraction should occur. In some embodiments, whether refraction occurs is determined based on whether an angle of incidence that a ray makes with the surface of the object610is greater than a critical angle associated with a medium of the object610and a medium surrounding the object610. Beyond the critical angle, total internal reflection can occur, rather than refraction, if a ray is attempting to travel from an optically denser medium to an optically thinner medium.

When refraction occurs, the rendering application130computes a direction vector630, t, an upper direction vector632, tu, and a lower direction vector632, tl, associated with the refracted ray cone634. In particular, the direction vector630, t, can be computed based on the direction vector604, d, associated with the middle ray603of the ray cone600and the indices of refraction of the media on either side of the hit point616, P, using Snell's law:
n1sin θ1=n2sin θ2,  (2)
where n1and n2are the indices of refraction of the two media, θ1is the incident angle of the middle ray603of the ray cone600, and θ2is the refracted angle of a middle ray of the refracted ray cone634. The upper direction vector632, tu, can be computed using Snell's law based on an upper direction vector608, denoted by du, that is associated with one side of the ray cone630; the indices of refraction, n1and n2, of the media on either side of the hit point616, P; and a rotated normal vector626, denoted by nu, that is computed based on a curvature of the surface of the object610at the hit point616, P. In particular, the refracted angle (θ2in equation (2)) of the upper direction vector632, tu, can be computed with respect to the rotated normal vector626, nu. Similarly, the lower direction vector632, tl, can be computed using Snell's law based on a lower direction vector606, denoted by dl, that is associated with another side of the ray cone630; the indices of refraction, n1and n2, of the media on either side of the hit point616, P; and a rotated normal vector622, denoted by nl, that is computed based on a curvature of the surface of the object610at the hit point616, P, with a refracted angle of the lower direction vector632, tl, being computed with respect to the rotated normal vector622, nl.

Then, the rendering application130computes a width of the refracted ray cone634based on distances from the hit point616, P, to lines631and629defined by the upper direction vector632, tu, and the lower direction vector628, tl, respectively, along a direction orthogonal to the direction vector630, t. In some embodiments, the width of the refracted ray cone634is computed as
w=wu+wl,  (3)
where wuis computed as the length along the direction that is orthogonal to the direction vector630, t, from the hit point616, P, to the line631defined by the upper direction vector632, tu, and wlis computed as the length along an opposite direction that is orthogonal to the direction vector630, t, from the hit point616, P, to the line629defined by the lower direction vector628, tl. In such cases, a line in the direction that is orthogonal to the direction vector630, t, can be intersected with the line631defined by the upper direction vector632, tu, and a line in the opposite direction that is orthogonal to the direction vector630, t, can be intersected with the line629defined by the lower direction vector628, tl, in order to compute the lengths wuand wl.

In addition, the rendering application130can compute a half cone angle, denoted by α2, of the refracted ray cone634as half of the angle between the upper direction vector632, tu, and the lower direction vector628, tl, It should be noted that the refracted ray cone634can either be expanding or contracting. In some embodiments, the half cone angle α2can be computed together with a sign indicating whether the refracted ray cone634is expanding or contracting as
α2=½arccos(tu·tl)sign(txutyl−tyutxl),  (4)
where sign(txutyl−tyutxl) is part of a cross product in 2D that indicates, via a sign, whether the refracted ray cone634is expanding or contracting.

AlthoughFIG.6is described with respect to the middle ray603, the upper ray607, and the lower ray605being refracted, in some cases, one or more such rays may be totally internally reflected. As described, total internal reflection can occur when (1) the angle of incidence a ray makes with the surface of an object is greater than a critical angle associated with a medium of the object and a surrounding medium, and (2) the ray is attempting to travel from an optically denser medium to an optically thinner medium. In some embodiments, when the middle ray of a ray cone is totally internally reflected, then the rendering application130generates a reflected ray cone rather than a refracted ray cone. The reflected ray cone can be generated in any technically feasible manner, including using well-known techniques. On the other hand, when the upper ray is totally internally reflected (but the middle ray is not totally internally reflected), then the rendering application130generates a refracted ray cone according to the technique described above, except the upper direction vector632, tu, of the refracted ray cone is computed as:

tu=du-(nu·du)⁢nudu-(nu·du)⁢nu.(5)
Alternatively, n may be used in equation (5) instead of nu. Similarly, when the lower ray is totally internally reflected (but the middle ray is not totally internally reflected), then the rendering application130can generate a refracted ray cone according to the technique described above, except the lower direction vector628, tl, of the refracted ray cone is computed as:

tl=dl-(nl·dl)⁢nldl-(nl·dl)⁢nl.(6)
Alternatively, n may be used in equation (6) instead of nl.

Although described herein primarily with respect to perfect refractions, techniques disclosed herein may also be used for rough refractions when, e.g., a microfacet-based bidirectional transmittance distribution function (BTDF) is used to generate a randomized refracted direction based on surface roughness. In some embodiments, a half-vector used for refracting the incident direction of a ray may be used as a normal, because the half vector is the normal of the microfacet that is used to refract the ray. In such cases, techniques for stochastic evaluation of microfacet BTDFs can be used to generate the half-vector. In other embodiments, the half-vector may be calculated using:

n=η⁢t+dη⁢t+d(7)

FIG.7illustrates an approximation of a refracted ray cone, according to various embodiments. As shown, a refracted ray cone704that is generated using the approach described above in conjunction withFIG.6is a close approximation of a refracted ray cone702generated by refracting multiple rays710i(referred to herein collectively as rays710and individually as a ray710) of a ray cone700. In particular, the refracted ray cone704grows at approximately the same rate as the refracted ray cone702. As a result, the refracted ray cone704can be used to approximate a footprint of the refracted ray cone702without altering the direction of a refraction of a middle ray of the ray cone700as a middle ray of the refracted ray cone704.

Illustratively, the geometry of the ray cone700differs significantly from the geometry of the refracted ray cone702, and the refracted ray cone704only approximates the geometry of the refracted ray cone702. In some embodiments, the rendering application130performs isotropic texture filtering prior to refractions and anisotropic texture filtering after refractions, in order to compensate for the approximations made using refracted ray cones. For example, anisotropic filtering could be performed to compensate for imperfections in the refracted ray cone704relative to the refracted ray cone702. In other embodiments, only isotropic texture filtering may be performed. In some embodiments, textures may be sampled without performing texture filtering in some cases. For example, when the very first hit of a ray cone along a path is refractive, no texture filtering could be performed prior to the refraction.

FIG.8Aillustrates an exemplar image800rendered using refracted ray cones and isotropic texture filtering, according to various embodiments. As shown, the image800depicts a virtual 3D scene that includes glass objects, and the image800is rendered from a view such that most of the scene is seen through the glass objects. Also shown are zoom-ins802and804of two regions within the image800.

FIG.8Billustrates an exemplar image810rendered using refracted ray cones and anisotropic texture filtering, according to other various embodiments. As shown, the exemplar image810was rendered by performing anisotropic texture filtering after refractions, as described above in conjunction withFIGS.5and7. In some embodiments, anisotropic texture filtering may be performed after refractions to compensate for the approximations made using refracted ray cones. Also shown are zoom-ins812and814of two regions within the image810.

FIG.8Cillustrates an exemplar ground truth image820, according to the prior art. The ground truth image820was generated by stochastically sampling a screen space ray cone through a pixel with 10k samples per pixel. Also shown are zoom-ins822and824of two regions within the ground truth image820.

As shown inFIGS.8A-C, the image810that is rendered using refracted ray cones and anisotropic texture filtering is closer to the ground truth image820than the image800that is rendered using refracted ray cones and isotropic texture filtering. In addition, anisotropic texture filtering produces results that are closer to the ground truth in the region in the zoom-in812than the region in the zoom-in814, because ray cones model circular cones and the region in the zoom-in814requires more than circular cones.

FIG.9Aillustrates an exemplar image900rendered using refracted ray cones and isotropic texture filtering, according to various embodiments, andFIG.9Billustrates an exemplar image910rendered using full resolution textures (mip0), according to the prior art. As shown, the images900and910were rendered using 1000 samples per pixel (ssp). On the same hardware, the image900rendered using refracted ray cones and isotropic texture filtering can be rendered more quickly than the image910rendered using full resolution textures. For example, experience has shown that ray cone tracing with isotropic texture filtering, described above in conjunction withFIGS.5-7, is typically approximately 10% faster than differential ray tracing with isotropic texture filtering and approximately 12% faster than differential ray tracing with anisotropic texture filtering. Further, the image900rendered using refracted ray cones and isotropic texture filtering is nearly visually identical to the image910rendered using full resolution textures.

FIG.10is a flow diagram of method steps for computing a pixel color via a ray cone tracing technique that implements refracted ray cones, according to various embodiments. Although the method steps are described in conjunction with the systems ofFIGS.1-4, persons skilled in the art will understand that any system configured to perform the method steps in any order falls within the scope of the present embodiments. Although described with respect to tracing a single ray cone, the method steps can be repeated to trace multiple ray cones when rendering an image.

As shown, a method1000begins at step1002, where the rendering application130traces a ray cone through a scene until the ray cone intersects geometry within the scene at a hit point. In particular, the ray cone can be traced through a pixel in a screen space into the scene until the ray cone intersects a triangle in the geometry at the hit point.

At step1004, the rendering application130determines whether the surface of the geometry at the hit point is textured. If the surface of the geometry at the hit point is textured, then, at step1006, the rendering application130causes the texture unit of a GPU to perform texture filtering based on one or more textures associated with the surface of the geometry. Any technically feasible texture filtering may be performed, such as isotropic texture filtering or anisotropic texture filtering. In some embodiments, isotropic texture filtering is performed prior to refractions, and anisotropic texture filtering is performed subsequent to refractions in order to compensate for imperfections in refracted ray cones. In some embodiments, textures may be sampled without performing texture filtering in some cases. For example, when the very first hit of a ray cone along a path is refractive, no texture filtering could be performed prior to the refraction.

At step1008, the rendering application130receives a filtered texture value from the texture unit of the GPU. The filtered texture value represents a texture color associated with the pixel in the screen space through which the ray cone was traced at step1002.

At step1010, the rendering application130applies or accumulates the filtered texture value to the pixel through which the ray cone was traced at step1002. The applied or accumulated texture filter value contributes to the color of the pixel in a rendered image. As described, the rendered image can be, e.g., an image or frame within a video game or film, an image generated by an architectural or design application or any other application, or the like. Although described herein with respect to applying or accumulating the anisotropic filtered texture value to the pixel, in other embodiments, the filtered texture value may be used in any technically feasible manner.

At step1012, the rendering application130determines whether refraction occurs. In some embodiments, determining whether refraction occurs includes determining whether an angle of incidence that a middle ray of the ray cone makes with the surface of an object that the ray cone hits is greater than a critical angle associated with a medium of the object and a surrounding medium when the middle ray is attempting to travel from an optically denser medium to an optically thinner medium. Beyond the critical angle, light rays are totally internally reflected, rather than refracted. Determining whether refraction occurs can further include determining whether the middle ray is reflected when the middle ray is attempting to travel from an optically thinner medium to an optically denser medium.

If refraction occurs, then at step1014, the rendering application130generates a refracted ray cone.FIG.11is a flow diagram of method steps for generating the refracted ray cone at step1014, according to various embodiments. Although the method steps are described in conjunction with the systems ofFIGS.1-4, persons skilled in the art will understand that any system configured to perform the method steps in any order falls within the scope of the present embodiments.

As shown, at step1102, the rendering application130computes a direction of a middle ray of the refracted ray cone based on a direction of the middle ray of the incident ray cone. As described, the direction of the middle ray of the refracted ray cone can be computed using Snell's law in some embodiments.

At step1104, the rendering application130computes a 2D coordinate frame. As described, in some embodiments, the 2D coordinate frame can be defined using the hit point as an origin, a direction of a vector that is normal to the surface of the object that the ray cone hits as one axis, and a direction of a vector that is in a same plane as a middle ray of the ray cone and tangent to the surface of the object as another axis.

At step1106, the rendering application130computes, in the 2D coordinate frame, an upper hit point and the direction of one side of the refracted ray cone. In some embodiments, the rendering application130may first determine whether an upper ray associated with a corresponding side of the incident ray cone is refracted or totally internally reflected. If the upper ray is refracted, then the direction of the side of the refracted ray cone can be computed based on the direction of the corresponding side of the incident ray cone and a rotated normal vector, as described above in conjunction withFIG.6. In addition, the rotated normal vector can be computed based on a curvature of the surface of the object that the ray cone hits. On the other hand, if the upper ray is totally internally reflected, then the direction of the side of the refracted ray cone can be computed according to equation 5.

At step1108, the rendering application130computes, in the 2D coordinate frame, a lower hit point and the direction of another side of the refracted ray cone. Similar to step1106, in some embodiments, the rendering application130may determine whether a lower ray associated with another corresponding side of the incident ray cone is refracted or totally internally reflected. If the lower ray is refracted, then the direction of the other side of the refracted ray cone can be computed based on the direction of the other corresponding side of the incident ray cone and another rotated normal vector, as described above in conjunction withFIG.6. On the other hand, if the lower ray is totally internally reflected, then the direction of the other side of the refracted ray cone can be computed according to equation 6.

At step1110, the rendering application130computes a width associated with the refracted ray cone based on the hit point at which the middle ray of the incident ray cone hit the object and rays associated with the directions of the middle ray and of the two sides of the refracted ray cone. In some embodiments, the width of the refracted ray cone is computed based on distances from the hit point to rays defined by direction vectors associated with the two sides of the refracted ray cone along a direction orthogonal to the middle ray of the refracted ray cone, as described above in conjunction withFIG.6.

At step1112, the rendering application130computes a spread angle associated with the refracted ray cone based on the directions of the two sides of the refracted ray cone. In some embodiments, the spread angle can be computed as a half cone angle along with a sign indicating whether the refracted ray cone is expanding or contracting, as described above in conjunction withFIG.6.

Returning toFIG.10, if the rendering application130determines at step1012that refraction does not occur, then the method1000continues to step1016, where the rendering application130determines whether reflection occurs based on whether the surface of the object that the ray cone hits is reflective.

If reflection does not occur, then the method1000ends. On the other hand, if reflection occurs, then the method1000continues to step1018, where the rendering application130generates a reflected ray cone. The reflected ray cone can be generated in any technically feasible manner, including using well-known techniques.

The method1000then returns to step1002, where the rendering application130traces the (reflected or refracted) ray cone through the scene until the ray cone intersects geometry within the scene at another hit point.

Although described herein primarily with respect to refraction at a surface, in some cases, an incident ray may be below the perturbed normal of a surface. To handle such cases, in some embodiments, the incident vector associated with a ray may be clamped to be at most 90 degrees away from the normal of a surface.

In sum, the disclosed techniques provide improved ray cone tracing techniques that implement refracted ray cones. In the improved ray cone tracing techniques, when a ray cone being traced through a virtual 3D scene hits a surface of geometry within the scene and undergoes refraction, a refracted ray cone is generated by (1) computing, in a 3D coordinate frame, the direction of a middle ray of the refracted ray cone and the directions of upper and lower sides of the refracted ray cone; and (2) given such computations, further computing a width of the refracted ray cone and a spread angle of the refracted cone. Then, the 3D refracted ray cone is traced through the scene. In addition, isotropic texture filtering can be performed prior to generating the refracted ray cone, and anisotropic texture filtering can be performed using the refracted ray cone and any subsequent ray cones, to determine the color of a pixel in a rendered image.

At least one technological advantage of the disclosed techniques relative to the prior art is that the disclosed techniques implement refracted ray cones that can be used to render more realistic-looking images of virtual scenes that include objects constructed from media that cause light to refract. In addition, the disclosed techniques use ray cone tracing, which is less computationally expensive than many ray tracing techniques, such as differential ray tracing, that can be used to trace refracted rays. These technological advantages represent one or more technological improvements over prior art approaches.

1. In some embodiments, a computer-implemented method for rendering one or more graphics images comprises tracing a ray cone through a three-dimensional (3D) graphics scene, generating a refracted ray cone based on the ray cone and a two-dimensional (2D) coordinate frame, and rendering a graphics image based on the refracted ray cone.

2. The computer-implemented method of clause 1, wherein generating the refracted ray cone comprises computing a first hit point and a direction of a middle ray associated with the refracted ray cone based on a direction of a middle ray associated with the ray cone, computing, in the 2D coordinate frame, a second hit point and a direction of a first side of the refracted ray cone based on a direction of a first side of the ray cone and a first rotated normal vector, and computing, in the 2D coordinate frame, a third hit point and a direction of a second side of the refracted ray cone based on a direction of a second side of the ray cone and a second rotated normal vector.

3. The computer-implemented method of clauses 1 or 2, further comprising computing the first rotated normal vector and the second rotated normal vector based on a curvature of an object hit by the ray cone in the 3D graphics scene.

4. The computer-implemented method of any of clauses 1-3, further comprising computing a width associated with the refracted ray cone based on the first hit point, a first ray associated with the direction of the first side of the refracted ray cone, and a second ray associated with the direction of the second side of the refracted ray cone.

5. The computer-implemented method of any of clauses 1-4, further comprising computing an angle associated with the refracted ray cone based on the direction of the first side of the refracted ray cone and the direction of the second side of the refracted ray cone.

6. The computer-implemented method of any of clauses 1-5, wherein rendering the graphics image comprises performing one or more isotropic texture filtering operations based on the refracted ray cone.

7. The computer-implemented method of any of clauses 1-6, wherein rendering the graphics image comprises performing one or more isotropic texture filtering operations based on the ray cone, and performing one or more anisotropic texture filtering operations based on the refracted ray cone.

8. The computer-implemented method of any of clauses 1-7, further comprising determining that refraction occurs at a hit point where the ray cone intersects an object in the 3D graphics scene.

9. The computer-implemented method of any of clauses 1-8, wherein the graphics image is rendered in association with a video game, a film, or an architectural or design application.

10. In some embodiments, one or more non-transitory computer-readable media store program instructions that, when executed by at least one processor, cause the at least one processor to perform the steps of tracing a ray cone through a three-dimensional (3D) graphics scene, generating a refracted ray cone based on the ray cone and a two-dimensional (2D) coordinate frame, and rendering a graphics image based on the refracted ray cone.

11. The one or more non-transitory computer-readable media of clause 10, wherein generating the refracted ray cone comprises computing a first hit point and a direction of a middle ray associated with the refracted ray cone based on a direction of a middle ray associated with the ray cone, computing, in the 2D coordinate frame, a second hit point and a direction of a first side of the refracted ray cone based on a direction of a first side of the ray cone and a first rotated normal vector, and computing, in the 2D coordinate frame, a third hit point and a direction of a second side of the refracted ray cone based on a direction of a second side of the ray cone and a second rotated normal vector.

12. The one or more non-transitory computer-readable media of clauses 10 or 11, the steps further comprising computing the first rotated normal vector and the second rotated normal vector based on a curvature of an object that the ray cone hits in the 3D graphics scene.

13. The one or more non-transitory computer-readable media of any of clauses 10-12, the steps further comprising computing a width associated with the refracted ray cone based on the first hit point, a first ray associated with the direction of the first side of the refracted ray cone, and a second ray associated with the direction of the second side of the refracted ray cone.

14. The one or more non-transitory computer-readable media of any of clauses 10-13, the steps further comprising computing an angle associated with the refracted ray cone based on the direction of the first side of the refracted ray cone and the direction of the second side of the refracted ray cone.

15. The one or more non-transitory computer-readable media of any of clauses 10-14, the steps further comprising determining at least one of the middle ray associated with the ray cone, a third ray associated with the direction of the first side of the ray cone, or a fourth ray associated with the direction of the second side of the ray cone is totally internally reflected.

16. The one or more non-transitory computer-readable media of any of clauses 10-15, the steps further comprising computing the 2D coordinate frame based on a middle ray associated with the ray cone.

17. The one or more non-transitory computer-readable media of any of clauses 10-16, wherein rendering the graphics image comprises performing one or more texture filtering operations based on the ray cone and the refracted ray cone.

18. The one or more non-transitory computer-readable media of any of clauses 10-17, wherein the one or texture filtering operations comprise one or more isotropic texture filtering operations that are performed prior to generating the refracted ray cone, and one or more anisotropic texture filtering operations that are performed subsequent to generating the refracted ray cone.

19. In some embodiments, a system comprises one or more memories storing instructions, and one or more processors that are coupled to the one or more memories and, when executing the instructions, are configured to trace a ray cone through a three-dimensional (3D) graphics scene, generate a refracted ray cone based on the ray cone and a two-dimensional (2D) coordinate frame, and render a graphics image based on the refracted ray cone.

20. The system of clause 19, wherein the one or more memories and the one or more processes are included in one or more computing systems that provide at least one of a virtualized environment or a cloud computing environment.

Any and all combinations of any of the claim elements recited in any of the claims and/or any elements described in this application, in any fashion, fall within the contemplated scope of the present disclosure and protection.

The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Aspects of the present embodiments may be embodied as a system, method or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “module” or “system.” Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine. The instructions, when executed via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions/acts specified in the flowchart and/or block diagram block or blocks. Such processors may be, without limitation, general purpose processors, special-purpose processors, application-specific processors, or field-programmable gate arrays.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

While the preceding is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.