Patch #8034: "soft" option for halos, which avoids ugly intersections

with geometry, and makes halos look more volumetric.

Patch contributed by Markus Ilmola, thanks!

5 files changed, 113 insertions, 64 deletions

diff --git a/source/blender/makesdna/DNA_material_types.h b/source/blender/makesdna/DNA_material_types.h
index a4c6120374a..361b240eabf 100644
--- a/source/blender/makesdna/DNA_material_types.h
+++ b/source/blender/makesdna/DNA_material_types.h
@@ -161,6 +161,7 @@ typedef struct Material {
 #define MA_SHLESS		4
 #define MA_WIRE			8
 #define MA_VERTEXCOL	16
+#define MA_HALO_SOFT	16
 #define MA_HALO			32
 #define MA_ZTRA			64
 #define MA_VERTEXCOLP	128
diff --git a/source/blender/render/intern/include/pixelshading.h b/source/blender/render/intern/include/pixelshading.h
index d2235784a59..ee7199a4295 100644
--- a/source/blender/render/intern/include/pixelshading.h
+++ b/source/blender/render/intern/include/pixelshading.h
@@ -45,7 +45,7 @@
  * mask is pixel coverage in bits
  * @return pointer to the object
  */
-void shadeHaloFloat(HaloRen *har, 
+int shadeHaloFloat(HaloRen *har, 
 					float *col, int zz, 
 					float dist, float xn, 
 					float yn, short flarec);
diff --git a/source/blender/render/intern/source/pixelshading.c b/source/blender/render/intern/source/pixelshading.c
index 6871a066c4f..6128a4823a4 100644
--- a/source/blender/render/intern/source/pixelshading.c
+++ b/source/blender/render/intern/source/pixelshading.c
@@ -24,6 +24,7 @@
  * ***** END GPL LICENSE BLOCK *****
  */
 
+#include <float.h>
 #include <math.h>
 #include <string.h>
 #include "BLI_arithb.h"
@@ -243,8 +244,36 @@ static void render_lighting_halo(HaloRen *har, float *colf)
 }
 
 
+/**
+ * Converts a halo z-buffer value to distance from the camera's near plane
+ * @param z The z-buffer value to convert
+ * @return a distance from the camera's near plane in blender units
+ */
+static float haloZtoDist(int z)
+{
+	float zco = 0;
 
-void shadeHaloFloat(HaloRen *har,  float *col, int zz, 
+	if(z >= 0x7FFFFF)
+		return 10e10;
+	else {
+		zco = (float)z/(float)0x7FFFFF;
+		if(R.r.mode & R_ORTHO)
+			return (R.winmat[3][2] - zco*R.winmat[3][3])/(R.winmat[2][2]);
+		else
+			return (R.winmat[3][2])/(R.winmat[2][2] - R.winmat[2][3]*zco);
+	}
+}
+
+/**
+ * @param col (float[4]) Store the rgb color here (with alpha)
+ * The alpha is used to blend the color to the background 
+ * color_new = (1-alpha)*color_background + color
+ * @param zz The current zbuffer value at the place of this pixel
+ * @param dist Distance of the pixel from the center of the halo squared. Given in pixels
+ * @param xn The x coordinate of the pixel relaticve to the center of the halo. given in pixels
+ * @param yn The y coordinate of the pixel relaticve to the center of the halo. given in pixels
+ */
+int shadeHaloFloat(HaloRen *har,  float *col, int zz, 
 					float dist, float xn,  float yn, short flarec)
 {
 	/* fill in col */
@@ -263,12 +292,40 @@ void shadeHaloFloat(HaloRen *har,  float *col, int zz,
 	}
 	else alpha= har->alfa;
 	
-	if(alpha==0.0) {
-		col[0] = 0.0;
-		col[1] = 0.0;
-		col[2] = 0.0;
-		col[3] = 0.0;
-		return;
+	if(alpha==0.0)
+		return 0;
+
+	/* soften the halo if it intersects geometry */
+	if(har->mat->mode & MA_HALO_SOFT) {
+		float segment_length, halo_depth, distance_from_z, visible_depth, soften;
+		
+		/* calculate halo depth */
+		segment_length= har->hasize*sasqrt(1.0f - dist/(har->rad*har->rad));
+		halo_depth= 2.0f*segment_length;
+
+		if(halo_depth < FLT_EPSILON)
+			return 0;
+
+		/* calculate how much of this depth is visible */
+		distance_from_z = haloZtoDist(zz) - haloZtoDist(har->zs);
+		visible_depth = halo_depth;
+		if(distance_from_z < segment_length) {
+			soften= (segment_length + distance_from_z)/halo_depth;
+
+			/* apply softening to alpha */
+			if(soften < 1.0f)
+				alpha *= soften;
+			if(alpha <= 0.0f)
+				return 0;
+		}
+	}
+	else {
+		/* not a soft halo. use the old softening code */
+		/* halo being intersected? */
+		if(har->zs> zz-har->zd) {
+			t= ((float)(zz-har->zs))/(float)har->zd;
+			alpha*= sqrt(sqrt(t));
+		}
 	}
 
 	radist= sqrt(dist);
@@ -366,21 +423,10 @@ void shadeHaloFloat(HaloRen *har,  float *col, int zz,
 			if(ster<1.0) dist*= sqrt(ster);
 		}
 	}
-	
-	/* halo being intersected? */
-	if(har->zs> zz-har->zd) {
-		t= ((float)(zz-har->zs))/(float)har->zd;
-		alpha*= sqrt(sqrt(t));
-	}
 
 	/* disputable optimize... (ton) */
-	if(dist<=0.00001) {
-		col[0] = 0.0;
-		col[1] = 0.0;
-		col[2] = 0.0;
-		col[3] = 0.0;
-		return;
-	}
+	if(dist<=0.00001)
+		return 0;
 	
 	dist*= alpha;
 	ringf*= dist;
@@ -441,6 +487,8 @@ void shadeHaloFloat(HaloRen *har,  float *col, int zz,
 	/* alpha requires clip, gives black dots */
 	if(col[3] > 1.0f)
 		col[3]= 1.0f;
+
+	return 1;
 }
 
 /* ------------------------------------------------------------------------- */
diff --git a/source/blender/render/intern/source/rendercore.c b/source/blender/render/intern/source/rendercore.c
index e36d8649036..15d41d45d88 100644
--- a/source/blender/render/intern/source/rendercore.c
+++ b/source/blender/render/intern/source/rendercore.c
@@ -165,9 +165,11 @@ static int calchalo_z(HaloRen *har, int zz)
 	return zz;
 }
 
+
+
 static void halo_pixelstruct(HaloRen *har, RenderLayer **rlpp, int totsample, int od, float dist, float xn, float yn, PixStr *ps)
 {
-	float col[4], accol[4];
+	float col[4], accol[4], fac;
 	int amount, amountm, zz, flarec, sample, fullsample, mask=0;
 	
 	fullsample= (totsample > 1);
@@ -180,23 +182,22 @@ static void halo_pixelstruct(HaloRen *har, RenderLayer **rlpp, int totsample, in
 		amount+= amountm;
 		
 		zz= calchalo_z(har, ps->z);
-		if(zz> har->zs) {
-			float fac;
-			
-			shadeHaloFloat(har, col, zz, dist, xn, yn, flarec);
-			flarec= 0;
-
-			if(fullsample) {
-				for(sample=0; sample<totsample; sample++)
-					if(ps->mask & (1 << sample))
-						addalphaAddfacFloat(rlpp[sample]->rectf + od*4, col, har->add);
-			}
-			else {
-				fac= ((float)amountm)/(float)R.osa;
-				accol[0]+= fac*col[0];
-				accol[1]+= fac*col[1];
-				accol[2]+= fac*col[2];
-				accol[3]+= fac*col[3];
+		if((zz> har->zs) || (har->mat->mode & MA_HALO_SOFT)) {
+			if(shadeHaloFloat(har, col, zz, dist, xn, yn, flarec)) {
+				flarec= 0;
+
+				if(fullsample) {
+					for(sample=0; sample<totsample; sample++)
+						if(ps->mask & (1 << sample))
+							addalphaAddfacFloat(rlpp[sample]->rectf + od*4, col, har->add);
+				}
+				else {
+					fac= ((float)amountm)/(float)R.osa;
+					accol[0]+= fac*col[0];
+					accol[1]+= fac*col[1];
+					accol[2]+= fac*col[2];
+					accol[3]+= fac*col[3];
+				}
 			}
 		}
 		
@@ -207,16 +208,14 @@ static void halo_pixelstruct(HaloRen *har, RenderLayer **rlpp, int totsample, in
 	/* now do the sky sub-pixels */
 	amount= R.osa-amount;
 	if(amount) {
-		float fac;
-
-		shadeHaloFloat(har, col, 0x7FFFFF, dist, xn, yn, flarec);
-
-		if(!fullsample) {
-			fac= ((float)amount)/(float)R.osa;
-			accol[0]+= fac*col[0];
-			accol[1]+= fac*col[1];
-			accol[2]+= fac*col[2];
-			accol[3]+= fac*col[3];
+		if(shadeHaloFloat(har, col, 0x7FFFFF, dist, xn, yn, flarec)) {
+			if(!fullsample) {
+				fac= ((float)amount)/(float)R.osa;
+				accol[0]+= fac*col[0];
+				accol[1]+= fac*col[1];
+				accol[2]+= fac*col[2];
+				accol[3]+= fac*col[3];
+			}
 		}
 	}
 
@@ -301,11 +300,11 @@ static void halo_tile(RenderPart *pa, RenderLayer *rl)
 							}
 							else {
 								zz= calchalo_z(har, *rz);
-								if(zz> har->zs) {
-									shadeHaloFloat(har, col, zz, dist, xn, yn, har->flarec);
-
-									for(sample=0; sample<totsample; sample++)
-										addalphaAddfacFloat(rlpp[sample]->rectf + od*4, col, har->add);
+								if((zz> har->zs) || (har->mat->mode & MA_HALO_SOFT)) {
+									if(shadeHaloFloat(har, col, zz, dist, xn, yn, har->flarec)) {
+										for(sample=0; sample<totsample; sample++)
+											addalphaAddfacFloat(rlpp[sample]->rectf + od*4, col, har->add);
+									}
 								}
 							}
 						}
@@ -1634,8 +1633,8 @@ static void renderhalo_post(RenderResult *rr, float *rectf, HaloRen *har)	/* pos
 					dist= xsq+ysq;
 					if(dist<har->radsq) {
 						
-						shadeHaloFloat(har, colf, 0x7FFFFF, dist, xn, yn, har->flarec);
-						addalphaAddfacFloat(rtf, colf, har->add);
+						if(shadeHaloFloat(har, colf, 0x7FFFFF, dist, xn, yn, har->flarec))
+							addalphaAddfacFloat(rtf, colf, har->add);
 					}
 					rtf+=4;
 				}
diff --git a/source/blender/src/buttons_shading.c b/source/blender/src/buttons_shading.c
index 880076de162..db531c7e6e3 100644
--- a/source/blender/src/buttons_shading.c
+++ b/source/blender/src/buttons_shading.c
@@ -3843,14 +3843,15 @@ static void material_panel_shading(Material *ma)
 		uiBlockSetCol(block, TH_BUT_SETTING1);
 		
 		uiBlockBeginAlign(block);
-		uiDefButBitI(block, TOG, MA_HALO_FLARE, B_MATPRV, "Flare",245,142,65,28, &(ma->mode), 0, 0, 0, 0, "Renders halo as a lensflare");
-		uiDefButBitI(block, TOG, MA_HALO_RINGS, B_MATPRV, "Rings",		245,123,65, 18, &(ma->mode), 0, 0, 0, 0, "Renders rings over halo");
-		uiDefButBitI(block, TOG, MA_HALO_LINES, B_MATPRV, "Lines",		245,104,65, 18, &(ma->mode), 0, 0, 0, 0, "Renders star shaped lines over halo");
-		uiDefButBitI(block, TOG, MA_STAR, B_MATPRV, "Star",		245,85,65, 18, &(ma->mode), 0, 0, 0, 0, "Renders halo as a star");
-		uiDefButBitI(block, TOG, MA_HALOTEX, B_MATPRV, "HaloTex",	245,66,65, 18, &(ma->mode), 0, 0, 0, 0, "Gives halo a texture");
-		uiDefButBitI(block, TOG, MA_HALOPUNO, B_MATPRV, "HaloPuno",	245,47,65, 18, &(ma->mode), 0, 0, 0, 0, "Uses the vertex normal to specify the dimension of the halo");
-		uiDefButBitI(block, TOG, MA_HALO_XALPHA, B_MATPRV, "X Alpha",	245,28,65, 18, &(ma->mode), 0, 0, 0, 0, "Uses extreme alpha");
-		uiDefButBitI(block, TOG, MA_HALO_SHADE, B_MATPRV, "Shaded",	245,9,65, 18, &(ma->mode), 0, 0, 0, 0, "Lets halo receive light and shadows");
+		uiDefButBitI(block, TOG, MA_HALO_FLARE,  B_MATPRV, "Flare",    245,161,65,28, &(ma->mode), 0, 0, 0, 0, "Renders halo as a lensflare");
+		uiDefButBitI(block, TOG, MA_HALO_RINGS,  B_MATPRV, "Rings",	   245,142,65,18, &(ma->mode), 0, 0, 0, 0, "Renders rings over halo");
+		uiDefButBitI(block, TOG, MA_HALO_LINES,  B_MATPRV, "Lines",	   245,123,65,18, &(ma->mode), 0, 0, 0, 0, "Renders star shaped lines over halo");
+		uiDefButBitI(block, TOG, MA_STAR,        B_MATPRV, "Star",	   245,104,65, 18, &(ma->mode), 0, 0, 0, 0, "Renders halo as a star");
+		uiDefButBitI(block, TOG, MA_HALOTEX,     B_MATPRV, "HaloTex",  245,85,65, 18, &(ma->mode), 0, 0, 0, 0, "Gives halo a texture");
+		uiDefButBitI(block, TOG, MA_HALOPUNO,    B_MATPRV, "HaloPuno", 245,66,65, 18, &(ma->mode), 0, 0, 0, 0, "Uses the vertex normal to specify the dimension of the halo");
+		uiDefButBitI(block, TOG, MA_HALO_XALPHA, B_MATPRV, "X Alpha",  245,47,65, 18, &(ma->mode), 0, 0, 0, 0, "Uses extreme alpha");
+		uiDefButBitI(block, TOG, MA_HALO_SHADE,  B_MATPRV, "Shaded",   245,28,65,  18, &(ma->mode), 0, 0, 0, 0, "Lets halo receive light and shadows");
+		uiDefButBitI(block, TOG, MA_HALO_SOFT,   B_MATPRV, "Soft",	   245,9,65,  18, &(ma->mode), 0, 0, 0, 0, "Softens the halo");
 		uiBlockEndAlign(block);
 	}
 	else {