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Diffstat (limited to 'src/mesa/swrast/s_aatriangle.c')
-rw-r--r--src/mesa/swrast/s_aatriangle.c46
1 files changed, 28 insertions, 18 deletions
diff --git a/src/mesa/swrast/s_aatriangle.c b/src/mesa/swrast/s_aatriangle.c
index d3d44d4e54..1b179bc613 100644
--- a/src/mesa/swrast/s_aatriangle.c
+++ b/src/mesa/swrast/s_aatriangle.c
@@ -1,4 +1,4 @@
-/* $Id: s_aatriangle.c,v 1.28 2003/01/22 15:03:09 brianp Exp $ */
+/* $Id: s_aatriangle.c,v 1.29 2003/01/25 18:57:13 brianp Exp $ */
/*
* Mesa 3-D graphics library
@@ -213,30 +213,40 @@ compute_coveragef(const GLfloat v0[3], const GLfloat v1[3],
for (i = 0; i < stop; i++) {
const GLfloat sx = x + samples[i][0];
const GLfloat sy = y + samples[i][1];
- const GLfloat fx0 = sx - v0[0];
- const GLfloat fy0 = sy - v0[1];
- const GLfloat fx1 = sx - v1[0];
- const GLfloat fy1 = sy - v1[1];
- const GLfloat fx2 = sx - v2[0];
- const GLfloat fy2 = sy - v2[1];
/* cross product determines if sample is inside or outside each edge */
- GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
- GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
- GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
+ GLfloat cross = (dx0 * (sy - v0[1]) - dy0 * (sx - v0[0]));
/* Check if the sample is exactly on an edge. If so, let cross be a
* positive or negative value depending on the direction of the edge.
*/
- if (cross0 == 0.0F)
- cross0 = dx0 + dy0;
- if (cross1 == 0.0F)
- cross1 = dx1 + dy1;
- if (cross2 == 0.0F)
- cross2 = dx2 + dy2;
- if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
- /* point is outside triangle */
+ if (cross == 0.0F)
+ cross = dx0 + dy0;
+ if (cross < 0.0F) {
+ /* sample point is outside first edge */
insideCount -= 1.0F;
stop = 16;
}
+ else {
+ /* sample point is inside first edge */
+ cross = (dx1 * (sy - v1[1]) - dy1 * (sx - v1[0]));
+ if (cross == 0.0F)
+ cross = dx1 + dy1;
+ if (cross < 0.0F) {
+ /* sample point is outside second edge */
+ insideCount -= 1.0F;
+ stop = 16;
+ }
+ else {
+ /* sample point is inside first and second edges */
+ cross = (dx2 * (sy - v2[1]) - dy2 * (sx - v2[0]));
+ if (cross == 0.0F)
+ cross = dx2 + dy2;
+ if (cross < 0.0F) {
+ /* sample point is outside third edge */
+ insideCount -= 1.0F;
+ stop = 16;
+ }
+ }
+ }
}
if (stop == 4)
return 1.0F;