Disabled commit of three days ago to speedup and improve hairstrand

raytracing with a linedist (cylinder) check. It didn't behave OK on strands
set to be more than 1 pixel (not to mention 10 pixels), and I have no time
now to fully check and code it.

Which is not really important either... In general, all 3d papers talk about
using shadowbuffer shadows for hair, which gives much nicer results for
dense volumes of polygons.

This commit restores regular (flat polygon) raytrace shadow for strands.
Also fixes some nasty bugs as reported. :)

1 files changed, 27 insertions, 7 deletions

diff --git a/source/blender/render/intern/source/ray.c b/source/blender/render/intern/source/ray.c
index 9ddd7ae14b2..d9f94c0be60 100644
--- a/source/blender/render/intern/source/ray.c
+++ b/source/blender/render/intern/source/ray.c
@@ -705,17 +705,21 @@ static int intersection2(VlakRen *vlr, float r0, float r1, float r2, float rx1,
 	return 0;
 }
 
+#if 0
 /* ray - line intersection */
+/* disabled until i got real & fast cylinder checking, this code doesnt work proper
+for faster strands */
+
 static int intersection_strand(Isect *is)
 {
-	float *v1, *v2;		/* length of strand */
+	float v1[3], v2[3];		/* length of strand */
 	float axis[3], rc[3], nor[3], radline, dist, len;
 	
 	/* radius strand */
 	radline= 0.5f*VecLenf(is->vlr->v1->co, is->vlr->v2->co);
 	
-	v1= is->vlr->v2->co;
-	v2= is->vlr->v3->co;
+	VecMidf(v1, is->vlr->v1->co, is->vlr->v2->co);
+	VecMidf(v2, is->vlr->v3->co, is->vlr->v4->co);
 	
 	VECSUB(rc, v1, is->start);	/* vector from base ray to base cylinder */
 	VECSUB(axis, v2, v1);		/* cylinder axis */
@@ -745,12 +749,26 @@ static int intersection_strand(Isect *is)
 		
 		labda = (dot1*dot2 - dot3*rlen)/div;
 		
+		radline/= sqrt(alen);
+		
 		/* labda: where on axis do we have closest intersection? */
-		if(labda>=0.0f && labda<=1.0f)
+		if(labda >= -radline && labda <= 1.0f+radline) {
+			VlakRen *vlr= is->vlrorig;
+			VertRen *v1= is->vlr->v1, *v2= is->vlr->v2, *v3= is->vlr->v3, *v4= is->vlr->v4;
+				/* but we dont do shadows from faces sharing edge */
+			
+			if(v1==vlr->v1 || v2==vlr->v1 || v3==vlr->v1 || v4==vlr->v1) return 0;
+			if(v1==vlr->v2 || v2==vlr->v2 || v3==vlr->v2 || v4==vlr->v2) return 0;
+			if(v1==vlr->v3 || v2==vlr->v3 || v3==vlr->v3 || v4==vlr->v3) return 0;
+			if(vlr->v4) {
+				if(v1==vlr->v4 || v2==vlr->v4 || v3==vlr->v4 || v4==vlr->v4) return 0;
+			}
 			return 1;
+		}
 	}
 	return 0;
 }
+#endif
 
 /* ray - triangle or quad intersection */
 static int intersection(Isect *is)
@@ -759,9 +777,11 @@ static int intersection(Isect *is)
 	float x0,x1,x2,t00,t01,t02,t10,t11,t12,t20,t21,t22,r0,r1,r2;
 	float m0, m1, m2, divdet, det1;
 	short ok=0;
-	
-	if(is->mode==DDA_SHADOW && is->vlr->flag & R_STRAND) 
-		return intersection_strand(is);
+
+	/* disabled until i got real & fast cylinder checking, this code doesnt work proper
+	   for faster strands */
+//	if(is->mode==DDA_SHADOW && is->vlr->flag & R_STRAND) 
+//		return intersection_strand(is);
 	
 	v1= is->vlr->v1; 
 	v2= is->vlr->v2;