Patent ID: 6466229
Filing Date: 2002-10-15
Classification: G06T,G09G

Abstract:
A graphics processing apparatus for drawing graphics, comprising:a display list generation part that converts vector information describing a drawing element or a clip element of graphics into straight line vector information obtained by approximating a polygon to a shape of vectors constructing the drawing element or clip element, sorts the straight line vectors included in the straight line vector information on the basis of vector start scan line coordinate values, and generates a display list constructed of information including the direction and gradient of each of the straight line vectors and the number of scan lines the straight line vector crosses or data equivalent to the above information; a merge process part that merges a display list indicative of the drawing element with a display list indicative of the clip element for restricting a drawing area of the drawing element which are generated by the display list generation part, thereby generating a display list in which the drawing element and the clip element mixedly exist; a display list storage part that stores the display list; a determination part that checks to see whether or not the number of the straight line vectors which cross a scan line is equal to or smaller than 2N (N is an integer of 1 or larger) in all of scan lines on the basis of the display list; a clip process part that clips the drawing element by the clip element with respect to the display list in which the clip element and the drawing element mixedly exist, thereby converting the display list to a display list having only drawing elements; a division process part that divides the display list having only the drawing elements converted by the clip process part so that the number of straight line vectors which cross all of the scan lines becomes equal to or smaller than 2N, thereby generating a plurality of display lists; an overlap removal part that generates a new display list obtained by removing an overlap of drawing areas from a plurality of display lists having the overlap in the drawing areas; and a display list drawing part having 2N DDA units that each calculate the coordinate value of an intersection between each scan line and the straight line vector on the basis of the display list, a sorting part that sorts output values from the DDA units, and a memory drawing part that obtains position information of a start point and an end point of a drawing line segment from the data sorted by the sorting part and fills a memory area between the start and end points.