- Fresnel V4.0

Based on feedback (thnx phase!) I found a big disadvantage of the 'real'
fresnel formula. It doesnt degrade to 0.0, causing 2-3 times too many
rays being fired compared to the previous one. So; a lot slower.

Now committed is a hybrid which allows (close to) real, and nice artistic
freedom, *and* it really goes to 0.0 and 1.0, assisting nicely in optimal
render times.
A real doc how it works (with pics) will be made before real release.

- Fixed bug in raytrace: the first renderpass didn't use fresnel for mirror.
- Fixed bug in previewrender, now it closer matches how fresnel renders

2 files changed, 24 insertions, 21 deletions

diff --git a/source/blender/render/intern/source/ray.c b/source/blender/render/intern/source/ray.c
index 030dbb7847b..c60b679465c 100644
--- a/source/blender/render/intern/source/ray.c
+++ b/source/blender/render/intern/source/ray.c
@@ -1366,7 +1366,7 @@ static void traceray(short depth, float *start, float *vec, float *col, VlakRen
 
 			if(shi.matren->mode & MA_RAYMIRROR) {
 				f= shi.matren->ray_mirror;
-				if(f!=0.0) f*= fresnel_fac(shi.view, shi.vn, shi.matren->ang, shi.matren->fresnel_mir);
+				if(f!=0.0) f*= fresnel_fac(shi.view, shi.vn, shi.matren->fresnel_mir_i, shi.matren->fresnel_mir);
 			}
 			else f= 0.0;
 			
@@ -1438,6 +1438,9 @@ static float jit_cube5[5*5*5*3]={0.0};
 static float *jitter_plane(int resol)
 {
 	extern float hashvectf[];
+	extern char hash[];
+	extern int temp_x, temp_y;
+	static int offs=0;
 	float dsize, *jit, *fp, *hv;
 	int x, y;
 	
@@ -1453,15 +1456,17 @@ static float *jitter_plane(int resol)
 	case 7: jit= jit_plane7; break;
 	default: jit= jit_plane8; break;
 	}
-	if(jit[0]!=0.0) return jit;
+	//if(jit[0]!=0.0) return jit;
+
+	offs++;
 
 	dsize= 1.0/(resol-1.0);
 	fp= jit;
-	hv= hashvectf;
+	hv= hashvectf+3*(hash[ (temp_x&3)+4*(temp_y&3) ]);
 	for(x=0; x<resol; x++) {
 		for(y=0; y<resol; y++, fp+= 3, hv+=3) {
-			fp[0]= -0.5 + (x+0.25*hv[0])*dsize;
-			fp[1]= -0.5 + (y+0.25*hv[1])*dsize;
+			fp[0]= -0.5 + (x+0.5*hv[0])*dsize;
+			fp[1]= -0.5 + (y+0.5*hv[1])*dsize;
 			fp[2]= fp[0]*fp[0] + fp[1]*fp[1];
 			if(resol>2)
 				if(fp[2]>0.3) fp[2]= 0.0;
@@ -1586,7 +1591,7 @@ void ray_trace(ShadeInput *shi, ShadeResult *shr, int mask)
 		}
 		
 		if(div!=0.0) {
-			i= shi->matren->ray_mirror;
+			i= shi->matren->ray_mirror*fresnel_fac(shi->view, shi->vn, shi->matren->fresnel_mir_i, shi->matren->fresnel_mir);
 			fr= shi->matren->mirr;
 			fg= shi->matren->mirg;
 			fb= shi->matren->mirb;
@@ -1619,7 +1624,7 @@ void ray_trace(ShadeInput *shi, ShadeResult *shr, int mask)
 		
 		if(do_mir) {
 		
-			i= shi->matren->ray_mirror*fresnel_fac(shi->view, shi->vn, shi->matren->ang, shi->matren->fresnel_mir);
+			i= shi->matren->ray_mirror*fresnel_fac(shi->view, shi->vn, shi->matren->fresnel_mir_i, shi->matren->fresnel_mir);
 			if(i!=0.0) {
 				fr= shi->matren->mirr;
 				fg= shi->matren->mirg;
diff --git a/source/blender/render/intern/source/rendercore.c b/source/blender/render/intern/source/rendercore.c
index cb7fa627e3c..1406cb51380 100644
--- a/source/blender/render/intern/source/rendercore.c
+++ b/source/blender/render/intern/source/rendercore.c
@@ -1500,24 +1500,18 @@ void calc_R_ref(ShadeInput *shi)
 
 }
 
-float fresnel_fac(float *view, float *vn, float ior, float fac)
+/* mix of 'real' fresnel and allowing control. grad defines blending gradient */
+float fresnel_fac(float *view, float *vn, float grad, float fac)
 {
-	float rf, t1, t2;
+	float t1, t2;
 	
 	if(fac==0.0) return 1.0;
 	
-	rf = ((ior-1.0)/(ior+1.0));
-	rf*= rf;
-
 	t1= (view[0]*vn[0] + view[1]*vn[1] + view[2]*vn[2]);
-	if(t1>0.0) t1= 1.0-t1;
-	else t1 = 1.0+t1;
+	if(t1>0.0)  t2= 1.0+t1;
+	else t2= 1.0-t1;
 	
-	if(fac==5.0) {
-		t2 = t1*t1;
-		t2= rf + (1.0-rf)*t1*t2*t2;
-	}
-	else t2= rf + (1.0-rf)*pow(t1, fac);
+	t2= grad + (1.0-grad)*pow(t2, fac);
 
 	if(t2<0.0) return 0.0;
 	else if(t2>1.0) return 1.0;
@@ -1547,7 +1541,7 @@ void shade_color(ShadeInput *shi, ShadeResult *shr)
 
 	if(ma->mode & (MA_ZTRA|MA_RAYTRANSP)) {
 		if(ma->fresnel_tra!=1.0) 
-			ma->alpha*= fresnel_fac(shi->view, shi->vn, ma->ang, ma->fresnel_tra);
+			ma->alpha*= fresnel_fac(shi->view, shi->vn, ma->fresnel_tra_i, ma->fresnel_tra);
 	}
 
 	shr->diff[0]= ma->r;
@@ -1879,7 +1873,7 @@ void shade_lamp_loop(ShadeInput *shi, ShadeResult *shr, int mask)
 
 	if(ma->mode & (MA_ZTRA|MA_RAYTRANSP)) {
 		if(ma->fresnel_tra!=1.0) 
-			ma->alpha*= fresnel_fac(shi->view, shi->vn, ma->ang, ma->fresnel_tra);
+			ma->alpha*= fresnel_fac(shi->view, shi->vn, ma->fresnel_tra_i, ma->fresnel_tra);
 
 		if(ma->spectra!=0.0) {
 
@@ -2182,6 +2176,8 @@ void shade_input_set_coords(ShadeInput *shi, float u, float v, int i1, int i2, i
 	}
 }
 
+int temp_x, temp_y;
+
   /* x,y: window coordinate from 0 to rectx,y */
   /* return pointer to rendered face */
 void *shadepixel(float x, float y, int vlaknr, int mask, float *col)
@@ -2193,6 +2189,8 @@ void *shadepixel(float x, float y, int vlaknr, int mask, float *col)
 	if(vlaknr< 0) {	/* error */
 		return NULL;
 	}
+temp_x= floor(x);
+temp_y= floor(y);
 	
 	if(vlaknr==0) {	/* sky */
 		col[0]= 0.0; col[1]= 0.0; col[2]= 0.0; col[3]= 0.0;