Patent ID: 6542152
Filing Date: 2003-04-01
Classification: G06T

Abstract:
A culling method, used in a computer graphics system, for determining the visibility of two planes at the same time, comprising the steps of:selecting 4 points from the surface of the 3-dimensional object to form two triangles, &Dgr;123 and &Dgr;423, sharing one adjacent side and two common vertices; determining the coordinates of the selected four vertices for the two triangles sharing vertices V2 and V3: assigning three vertices V1(x1, y1, z1), V2(x2, y2, z2), and V3(x3, y3, z3) for the first triangle &Dgr;123; assigning three vertices V4(x4, y4, z4), V2(x2, y2, z2), and V3(x3, y3, z3) for the second triangle &Dgr;423; computing the three common terms (y2z3âˆ’z2y3), (z2x3âˆ’x2z3), and (x2y3âˆ’y2x3); computing the culling equations x1(y2z3âˆ’z2y3)+y1(z2x3âˆ’x2z3)+z1(x2y3âˆ’y2x3) and x4(y2z3âˆ’z2y3)+y4(z2x3âˆ’x2z3)+z4(x2y3âˆ’y2x3) for &Dgr;123 and &Dgr;423, respectively; and determining the visibility of the two triangles according to the signs of the two culling equation: if &Dgr;>0, the plane tested being visible; if &Dgr;&lE;0, the plane tested being invisible.