* Fix for volumetric rendering. It previously wasn't multiplying

the emission component by the density at the current point, which 
made the volume too bright in less dense areas. This made it look 
too rough, as opposed to smooth as it should be. This makes the 
particle rendering look *much* better, thanks a bunch to ZanQdo for 
complaining and kicking my butt to make me realise the error.

Here's an example of how smooth it looks now:
http://mke3.net/blender/devel/rendering/volumetrics/smoke_test03.mov
http://mke3.net/blender/devel/rendering/volumetrics/smoke_test03.blend

Settings in existing files will have to be tweaked a bit, since 
what they were set up for before, was incorrect.

* Added two new interpolation types to Point Density: Constant and 
Root. These work similarly to in proportional edit for example, 
just gives a bit more choice over how hard-edged the particles 
should look.

4 files changed, 32 insertions, 14 deletions

diff --git a/source/blender/makesdna/DNA_texture_types.h b/source/blender/makesdna/DNA_texture_types.h
index d23672f9284..9c608302b22 100644
--- a/source/blender/makesdna/DNA_texture_types.h
+++ b/source/blender/makesdna/DNA_texture_types.h
@@ -132,7 +132,6 @@ typedef struct PointDensity {
 
 	short falloff_type;
 	float radius;
-
 	short source;
 	short pdpad[3];
 
@@ -422,6 +421,8 @@ typedef struct TexMapping {
 #define TEX_PD_FALLOFF_STD		0
 #define TEX_PD_FALLOFF_SMOOTH	1
 #define TEX_PD_FALLOFF_SHARP	2
+#define TEX_PD_FALLOFF_CONSTANT	3
+#define TEX_PD_FALLOFF_ROOT		4
 
 /* psys_cache_space */
 #define TEX_PD_OBJECTLOC	0
diff --git a/source/blender/render/intern/source/pointdensity.c b/source/blender/render/intern/source/pointdensity.c
index 4422b9fbbdd..c4124fba8bb 100644
--- a/source/blender/render/intern/source/pointdensity.c
+++ b/source/blender/render/intern/source/pointdensity.c
@@ -224,7 +224,6 @@ void free_pointdensities(Render *re)
 	}
 }
 
-
 void accum_density_std(void *userdata, int index, float squared_dist, float squared_radius)
 {
 	float *density = userdata;
@@ -249,6 +248,22 @@ void accum_density_sharp(void *userdata, int index, float squared_dist, float sq
 	*density+= dist*dist;
 }
 
+void accum_density_constant(void *userdata, int index, float squared_dist, float squared_radius)
+{
+	float *density = userdata;
+		
+	*density+= squared_radius;
+}
+
+void accum_density_root(void *userdata, int index, float squared_dist, float squared_radius)
+{
+	float *density = userdata;
+	const float dist = squared_radius - squared_dist;
+		
+	*density+= sqrt(dist);
+}
+
+
 #define MAX_POINTS_NEAREST	25
 int pointdensitytex(Tex *tex, float *texvec, TexResult *texres)
 {
@@ -267,7 +282,11 @@ int pointdensitytex(Tex *tex, float *texvec, TexResult *texres)
 		BLI_bvhtree_range_query(pd->point_tree, texvec, pd->radius, accum_density_smooth, &density);
 	else if (pd->falloff_type == TEX_PD_FALLOFF_SHARP)
 		BLI_bvhtree_range_query(pd->point_tree, texvec, pd->radius, accum_density_sharp, &density);
-
+	else if (pd->falloff_type == TEX_PD_FALLOFF_CONSTANT)
+		BLI_bvhtree_range_query(pd->point_tree, texvec, pd->radius, accum_density_constant, &density);
+	else if (pd->falloff_type == TEX_PD_FALLOFF_ROOT)
+		BLI_bvhtree_range_query(pd->point_tree, texvec, pd->radius, accum_density_root, &density);
+	
 	texres->tin = density;
 
 	/*
diff --git a/source/blender/render/intern/source/volumetric.c b/source/blender/render/intern/source/volumetric.c
index 4d138ea8545..5d28540f17a 100644
--- a/source/blender/render/intern/source/volumetric.c
+++ b/source/blender/render/intern/source/volumetric.c
@@ -152,7 +152,7 @@ void vol_get_emission(ShadeInput *shi, float *em, float *co, float density)
 	
 	do_volume_tex(shi, co, MAP_EMIT+MAP_COL, col, &emission);
 	
-	em[0] = em[1] = em[2] = emission;
+	em[0] = em[1] = em[2] = emission * density;
 	VecMulVecf(em, em, col);
 }
 
@@ -365,13 +365,10 @@ static void volumeintegrate(struct ShadeInput *shi, float *col, float *co, float
 	/* get radiance from all points along the ray due to participating media */
 	for (s = 0; s < nsteps; s++) {
 		if (s > 0) density = vol_get_density(shi, step_sta);
-	
-		/* there's only any point shading here
+		
+		/* there's only any use in shading here
 		 * if there's actually some density to shade! */
 		if (density > 0.01f) {
-			step_mid[0] = step_sta[0] + (stepvec[0] * 0.5);
-			step_mid[1] = step_sta[1] + (stepvec[1] * 0.5);
-			step_mid[2] = step_sta[2] + (stepvec[2] * 0.5);
 		
 			/* transmittance component (alpha) */
 			vol_get_attenuation(shi, tau, step_sta, step_end, density, stepsize);
@@ -379,9 +376,10 @@ static void volumeintegrate(struct ShadeInput *shi, float *col, float *co, float
 			tr[1] *= exp(-tau[1]);
 			tr[2] *= exp(-tau[2]);
 			
-			/* Terminate raymarching if transmittance is small */
-			//if ((tr[0] + tr[1] + tr[2] * 0.333f) < 0.01f) continue;
-			
+			step_mid[0] = step_sta[0] + (stepvec[0] * 0.5);
+			step_mid[1] = step_sta[1] + (stepvec[1] * 0.5);
+			step_mid[2] = step_sta[2] + (stepvec[2] * 0.5);
+		
 			/* incoming light via emission or scattering (additive) */
 			vol_get_emission(shi, step_emit, step_mid, density);
 			vol_get_scattering(shi, step_scatter, step_mid, stepsize, density);
diff --git a/source/blender/src/buttons_shading.c b/source/blender/src/buttons_shading.c
index 050dae6026e..7a154d084bc 100644
--- a/source/blender/src/buttons_shading.c
+++ b/source/blender/src/buttons_shading.c
@@ -758,7 +758,7 @@ static void texture_panel_pointdensity(Tex *tex)
 		
 		uiDefBut(block, LABEL, B_NOP, "Falloff:",
 			X2CLM1, yco-=BUTH, BUTW2, BUTH, 0, 0, 0, 0, 0, "");	
-		uiDefButS(block, MENU, B_REDR, "Standard %x0|Smooth %x1|Sharp %x2",
+		uiDefButS(block, MENU, B_REDR, "Standard %x0|Smooth %x1|Sharp %x2|Constant %x3|Root %x4",
 				X2CLM1, yco-=BUTH, BUTW2, BUTH, &pd->falloff_type, 0.0, 0.0, 0, 0, "Falloff type");
 		
 		yco = PANEL_YMAX;
@@ -4334,7 +4334,7 @@ static void material_panel_material_volume(Material *ma)
 	uiDefButF(block, NUM, B_MATPRV, "Step Size: ",
 		X2CLM1, yco-=BUTH, BUTW2, BUTH, &(ma->vol_shade_stepsize), 0.001, 100.0, 10, 2, "Step");
 	uiBlockEndAlign(block);
-	
+		
 	yco = PANEL_YMAX;
 	
 	uiDefButF(block, NUMSLI, B_MATPRV, "Density: ",