Apparatus and method for generating point sample masks in a graphics display system
First Claim
1. In a computer system, a computer implemented method of generating a point sample mask having an array of sample points corresponding to a pixel, wherein each sample point has associated information specifying whether said sample point is inside or outside a polygon, said information being used for rendering said pixel for display by said computer system, said method comprising the steps of:
- generating a first mask corresponding to a first edge of said polygon, said first mask specifying which ones of a first set of said sample points reside within a first half-plane defined by said first edge, wherein a sign of a vertical or horizontal distance metric corresponding to a first sample of said first set of sample points determines whether said first sample resides within said first half-plane;
generating a second mask corresponding to a second edge of said polygon, said second mask specifying which ones of a second set of sample points reside within a second half-plane defined by said second edge, wherein a sign of a vertical or horizontal distance metric corresponding to a second sample of said second set of sample points determines whether said second sample resides within said second half-plane;
generating a third mask corresponding to a third edge of said polygon, said third mask specifying which ones of a third set of sample points reside within a third half-plane defined by said third edge, wherein a sign of a vertical or horizontal distance metric corresponding to a third sample of said third set of sample points determines whether said third sample resides within said third half-plane;
merging said first mask, said second mask, and said third mask to generate said point sample mask.
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Abstract
In a computer graphics system, a method of generating a geometrically valid point sample mask corresponding to a pixel. A separate mask is generated for each edge of a polygon. These masks specify whether particular subsample points are within a half-plane defined by an edge of the polygon. This information is determined by examining the sign of vertical or horizontal distance metrics corresponding to those sample points. These separate masks are merged to form the final point sample mask. Thereby, the final point sample mask contains information specifying whether particular sample points reside within the polygon. This information is used in rendering the pixel for display by the computer graphics system.
53 Citations
26 Claims
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1. In a computer system, a computer implemented method of generating a point sample mask having an array of sample points corresponding to a pixel, wherein each sample point has associated information specifying whether said sample point is inside or outside a polygon, said information being used for rendering said pixel for display by said computer system, said method comprising the steps of:
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generating a first mask corresponding to a first edge of said polygon, said first mask specifying which ones of a first set of said sample points reside within a first half-plane defined by said first edge, wherein a sign of a vertical or horizontal distance metric corresponding to a first sample of said first set of sample points determines whether said first sample resides within said first half-plane; generating a second mask corresponding to a second edge of said polygon, said second mask specifying which ones of a second set of sample points reside within a second half-plane defined by said second edge, wherein a sign of a vertical or horizontal distance metric corresponding to a second sample of said second set of sample points determines whether said second sample resides within said second half-plane; generating a third mask corresponding to a third edge of said polygon, said third mask specifying which ones of a third set of sample points reside within a third half-plane defined by said third edge, wherein a sign of a vertical or horizontal distance metric corresponding to a third sample of said third set of sample points determines whether said third sample resides within said third half-plane; merging said first mask, said second mask, and said third mask to generate said point sample mask. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In a computer system, an apparatus for generating a point sample mask having an array of sample points corresponding to a pixel, wherein each sample point has associated information specifying whether said sample point is inside or outside a polygon, said information being used for rendering said pixel for display by said computer system, said apparatus comprising:
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a first generator for generating a first mask corresponding to a first edge of said polygon, said first mask specifying which ones of a first set of said sample points reside within a first half-plane defined by said first edge, wherein a sign of a vertical or horizontal distance metric corresponding to a first sample of said first set of sample points determines whether said first sample resides within said first half-plane; a second generator coupled to said first generator for generating a second mask corresponding to a second edge of said polygon, said second mask specifying which ones of a second set of sample points reside within a second half-plane defined by said second edge, wherein a sign of a vertical or horizontal distance metric corresponding to a second sample of said second set of sample points determines whether said second sample resides within said second half-plane; a third generator coupled to said second generator for generating a third mask corresponding to a third edge of said polygon, said third mask specifying which ones of a third set of sample points reside within a third half-plane defined by said third edge, wherein a sign of a vertical or horizontal distance metric corresponding to a third sample of said third set of sample points determines whether said third sample resides within said third half-plane; a circuit coupled to said first, said second, and said third generators for merging said first mask, said second mask, and said third mask, resulting in said point sample mask. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification