Cycles: Subsurface Scattering

New features:

* Bump mapping now works with SSS
* Texture Blur factor for SSS, see the documentation for details:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#Subsurface_Scattering

Work in progress for feedback:

Initial implementation of the "BSSRDF Importance Sampling" paper, which uses
a different importance sampling method. It gives better quality results in
many ways, with the availability of both Cubic and Gaussian falloff functions,
but also tends to be more noisy when using the progressive integrator and does
not give great results with some geometry. It works quite well for the
non-progressive integrator and is often less noisy there.

This code may still change a lot, so unless you're testing it may be best to
stick to the Compatible falloff function.

Skin test render and file that takes advantage of the gaussian falloff:
http://www.pasteall.org/pic/show.php?id=57661
http://www.pasteall.org/pic/show.php?id=57662
http://www.pasteall.org/blend/23501

5 files changed, 38 insertions, 6 deletions

diff --git a/source/blender/editors/space_node/drawnode.c b/source/blender/editors/space_node/drawnode.c
index 5cc22b25f72..a011657ce51 100644
--- a/source/blender/editors/space_node/drawnode.c
+++ b/source/blender/editors/space_node/drawnode.c
@@ -907,6 +907,11 @@ static void node_shader_buts_glossy(uiLayout *layout, bContext *UNUSED(C), Point
 	uiItemR(layout, ptr, "distribution", 0, "", ICON_NONE);
 }
 
+static void node_shader_buts_subsurface(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
+{
+	uiItemR(layout, ptr, "falloff", 0, "", ICON_NONE);
+}
+
 static void node_shader_buts_toon(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
 	uiItemR(layout, ptr, "component", 0, "", ICON_NONE);
@@ -1039,6 +1044,9 @@ static void node_shader_set_butfunc(bNodeType *ntype)
 		case SH_NODE_BSDF_REFRACTION:
 			ntype->uifunc = node_shader_buts_glossy;
 			break;
+		case SH_NODE_SUBSURFACE_SCATTERING:
+			ntype->uifunc = node_shader_buts_subsurface;
+			break;
 		case SH_NODE_BSDF_TOON:
 			ntype->uifunc = node_shader_buts_toon;
 			break;
diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index fda696f2e28..6984d0299e8 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -965,6 +965,11 @@ typedef struct NodeShaderNormalMap {
 #define SHD_NORMAL_MAP_BLENDER_OBJECT	3
 #define SHD_NORMAL_MAP_BLENDER_WORLD	4
 
+/* tangent */
+#define SHD_SUBSURFACE_COMPATIBLE		0
+#define SHD_SUBSURFACE_CUBIC			1
+#define SHD_SUBSURFACE_GAUSSIAN			2
+
 /* blur node */
 #define CMP_NODE_BLUR_ASPECT_NONE		0
 #define CMP_NODE_BLUR_ASPECT_Y			1
diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index b4576509098..7be333247a6 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -3640,6 +3640,25 @@ static void def_sh_tangent(StructRNA *srna)
 	RNA_def_struct_sdna_from(srna, "bNode", NULL);
 }
 
+
+static void def_sh_subsurface(StructRNA *srna)
+{
+	static EnumPropertyItem prop_subsurface_falloff_items[] = {
+		{SHD_SUBSURFACE_COMPATIBLE, "COMPATIBLE", 0, "Compatible", "Subsurface scattering falloff compatible with previous versions"},
+		{SHD_SUBSURFACE_CUBIC, "CUBIC", 0, "Cubic", "Simple cubic falloff function"},
+		{SHD_SUBSURFACE_GAUSSIAN, "GAUSSIAN", 0, "Gaussian", "Normal distribution, multiple can be combined to fit more complex profiles"},
+		{0, NULL, 0, NULL, NULL}
+	};
+
+	PropertyRNA *prop;
+	
+	prop = RNA_def_property(srna, "falloff", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "custom1");
+	RNA_def_property_enum_items(prop, prop_subsurface_falloff_items);
+	RNA_def_property_ui_text(prop, "Falloff", "Function to determine how much light nearby points contribute based on their distance to the shading point");
+	RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
+}
+
 static void def_sh_script(StructRNA *srna)
 {
 	PropertyRNA *prop;
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index eeec40c911f..6e2c30f98cf 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -86,7 +86,7 @@ DefNode( ShaderNode,     SH_NODE_BSDF_TRANSLUCENT,   0,                      "BS
 DefNode( ShaderNode,     SH_NODE_BSDF_TRANSPARENT,   0,                      "BSDF_TRANSPARENT",   BsdfTransparent,  "Transparent BSDF",  ""       )
 DefNode( ShaderNode,     SH_NODE_BSDF_VELVET,        0,                      "BSDF_VELVET",        BsdfVelvet,       "Velvet BSDF",       ""       )
 DefNode( ShaderNode,     SH_NODE_BSDF_TOON,          def_toon,               "BSDF_TOON",          BsdfToon,         "Toon BSDF",         ""       )
-DefNode( ShaderNode,     SH_NODE_SUBSURFACE_SCATTERING, 0,                   "SUBSURFACE_SCATTERING",SubsurfaceScattering,"Subsurface Scattering","")
+DefNode( ShaderNode,     SH_NODE_SUBSURFACE_SCATTERING, def_sh_subsurface,   "SUBSURFACE_SCATTERING",SubsurfaceScattering,"Subsurface Scattering","")
 DefNode( ShaderNode,     SH_NODE_VOLUME_TRANSPARENT, 0,                      "VOLUME_TRANSPARENT", VolumeTransparent,"Transparent Volume",""       )
 DefNode( ShaderNode,     SH_NODE_VOLUME_ISOTROPIC,   0,                      "VOLUME_ISOTROPIC",   VolumeIsotropic,  "Isotropic Volume",  ""       )
 DefNode( ShaderNode,     SH_NODE_EMISSION,           0,                      "EMISSION",           Emission,         "Emission",          ""       )
diff --git a/source/blender/nodes/shader/nodes/node_shader_subsurface_scattering.c b/source/blender/nodes/shader/nodes/node_shader_subsurface_scattering.c
index 3bdc3813fd7..8ad529d192e 100644
--- a/source/blender/nodes/shader/nodes/node_shader_subsurface_scattering.c
+++ b/source/blender/nodes/shader/nodes/node_shader_subsurface_scattering.c
@@ -30,11 +30,11 @@
 /* **************** OUTPUT ******************** */
 
 static bNodeSocketTemplate sh_node_subsurface_scattering_in[] = {
-	{	SOCK_RGBA, 1, N_("Color"),		0.8f, 0.8f, 0.8f, 1.0f, 0.0f, 1.0f},
-	{	SOCK_FLOAT, 1, N_("Scale"),		1.0, 0.0f, 0.0f, 0.0f, 0.0f, 1000.0f},
-	{	SOCK_VECTOR, 1, N_("Radius"),	1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 100.0f},
-	//{	SOCK_FLOAT, 1, N_("IOR"),		1.3f, 0.0f, 0.0f, 0.0f, 1.0f, 1000.0f},
-	{	SOCK_VECTOR, 1, N_("Normal"),	0.0f, 0.0f, 0.0f, 1.0f, -1.0f, 1.0f, PROP_NONE, SOCK_HIDE_VALUE},
+	{	SOCK_RGBA, 1, N_("Color"),			0.8f, 0.8f, 0.8f, 1.0f, 0.0f, 1.0f},
+	{	SOCK_FLOAT, 1, N_("Scale"),			1.0, 0.0f, 0.0f, 0.0f, 0.0f, 1000.0f},
+	{	SOCK_VECTOR, 1, N_("Radius"),		1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 100.0f},
+	{	SOCK_FLOAT, 1, N_("Texture Blur"),	0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f},
+	{	SOCK_VECTOR, 1, N_("Normal"),		0.0f, 0.0f, 0.0f, 1.0f, -1.0f, 1.0f, PROP_NONE, SOCK_HIDE_VALUE},
 	{	-1, 0, ""	}
 };