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-rw-r--r--src/mesa/pipe/draw/draw_cull.c12
-rw-r--r--src/mesa/pipe/draw/draw_twoside.c12
2 files changed, 15 insertions, 9 deletions
diff --git a/src/mesa/pipe/draw/draw_cull.c b/src/mesa/pipe/draw/draw_cull.c
index 863686f150..e563f9f45f 100644
--- a/src/mesa/pipe/draw/draw_cull.c
+++ b/src/mesa/pipe/draw/draw_cull.c
@@ -40,7 +40,7 @@
struct cull_stage {
struct draw_stage stage;
- GLuint mode; /**< one of PIPE_WINDING_x */
+ GLuint winding; /**< which winding(s) to cull (one of PIPE_WINDING_x) */
};
@@ -54,7 +54,7 @@ static void cull_begin( struct draw_stage *stage )
{
struct cull_stage *cull = cull_stage(stage);
- cull->mode = stage->draw->setup.cull_mode;
+ cull->winding = stage->draw->setup.cull_mode;
stage->next->begin( stage->next );
}
@@ -78,10 +78,12 @@ static void cull_tri( struct draw_stage *stage,
header->det = ex * fy - ey * fx;
if (header->det != 0) {
- /* non-zero area */
- GLuint mode = (header->det > 0) ? PIPE_WINDING_CW : PIPE_WINDING_CCW;
+ /* if (det > 0 then Z points toward camera and triangle is
+ * counter-clockwise winding.
+ */
+ GLuint winding = (header->det > 0) ? PIPE_WINDING_CCW : PIPE_WINDING_CW;
- if ((mode & cull_stage(stage)->mode) == 0) {
+ if ((winding & cull_stage(stage)->winding) == 0) {
/* triangle is not culled, pass to next stage */
stage->next->tri( stage->next, header );
}
diff --git a/src/mesa/pipe/draw/draw_twoside.c b/src/mesa/pipe/draw/draw_twoside.c
index e86123e84d..9f26335fb6 100644
--- a/src/mesa/pipe/draw/draw_twoside.c
+++ b/src/mesa/pipe/draw/draw_twoside.c
@@ -35,8 +35,7 @@
struct twoside_stage {
struct draw_stage stage;
-
- GLfloat facing;
+ GLfloat sign; /**< +1 or -1 */
const GLuint *lookup;
};
@@ -51,7 +50,12 @@ static void twoside_begin( struct draw_stage *stage )
{
struct twoside_stage *twoside = twoside_stage(stage);
- twoside->facing = (stage->draw->setup.front_winding == PIPE_WINDING_CW) ? 1 : -1;
+ /*
+ * We'll multiply the primitive's determinant by this sign to determine
+ * if the triangle is back-facing (negative).
+ * sign = 1 for CCW, -1 for CW
+ */
+ twoside->sign = (stage->draw->setup.front_winding == PIPE_WINDING_CCW) ? 1 : -1;
stage->next->begin( stage->next );
}
@@ -94,7 +98,7 @@ static void twoside_tri( struct draw_stage *stage,
{
struct twoside_stage *twoside = twoside_stage(stage);
- if (header->det * twoside->facing < 0) {
+ if (header->det * twoside->sign < 0.0) {
/* this is a back-facing triangle */
struct prim_header tmp;