*late culling

1 files changed, 17 insertions, 5 deletions

diff --git a/src/core/rasterizer.c b/src/core/rasterizer.c
index 28ae639..c5745ba 100644
--- a/src/core/rasterizer.c
+++ b/src/core/rasterizer.c
@@ -86,19 +86,31 @@ void ssrR_triangle(
 	Vec4* CA, Vec4* CB, Vec4* CC, 
 	uint IA, uint IB, uint IC, 
 	Program* program, 
-	UniformCollection* uniforms 
+	UniformCollection* uniforms, 
+	bool early_culled
 ) {
 	ssr_assert(CA && CB && CC && program);
 
+	/*late back face culling*/
+	if (!early_culled && ssr_isenable(ENABLE_BACKFACECULL)) {
+		float w0 = 1 / CA->w, w1 = 1 / CB->w, w2 = 1 / CC->w;
+		Vec2 ab, ac;
+		ab.x = CB->x * w1 - CA->x * w0;
+		ab.y = CB->y * w1 - CA->y * w0;
+		ac.x = CC->x * w2 - CA->x * w0;
+		ac.y = CC->y * w2 - CA->y * w0;
+		if (ab.x * ac.y - ab.y * ac.x <= 0) {
+			return;
+		}
+	}
+
 	Vec4 SA, SB, SC;
 	internal_vec4_dividewnoz(CA, &SA); ssrU_viewport(&SA, &SA);
 	internal_vec4_dividewnoz(CB, &SB); ssrU_viewport(&SB, &SB);
 	internal_vec4_dividewnoz(CC, &SC); ssrU_viewport(&SC, &SC);
 
-/*
-	puttriangle(&SA, &SB, &SC, 0xffff0000);
-	return;
-*/
+	//puttriangle(&SA, &SB, &SC, 0xffff0000);
+	//return;
 
 	Vec4 *sa = &SA, *sb = &SB, *sc = &SC, *tmp; 
 	Vec4 *v4tmp;