Vertex processing when w=0

Details Vertex processing when w=0 Vertex processing when w=0

2005-08-25

2008-09-02

Nguyen, Phu K. (Department: 2628)

Computer graphics processing and selective visual display system

Computer graphics processing

Three-dimension

C382S104000, C708S207000

Reexamination Certificate

active

07420557

ABSTRACT:
Vertices defining a graphics primitive may be processed in homogeneous space and projected into normalized device coordinate space by dividing each coordinate of a vertex by w. When the w coordinate for a vertex is equal to zero, the projected coordinates are set equal to the homogeneous coordinate values. During a viewport transform operation, only the viewport scale is applied rather than applying the viewport scale and viewport bias to produce the vertex in device coordinate space (screen space). Furthermore, when an edge slope is computed for a vertex with a w coordinate equal to zero, the slope is set equal to the vertex in device coordinate space rather than the difference of the two vertices defining the edge. Therefore, a vertex at infinity is correctly positioned avoiding the introduction of visual artifacts.

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