Cycles: initial subsurface multiple scattering support. It's not working as

well as I would like, but it works, just add a subsurface scattering node and
you can use it like any other BSDF.

It is using fully raytraced sampling compatible with progressive rendering
and other more advanced rendering algorithms we might used in the future, and
it uses no extra memory so it's suitable for complex scenes.

Disadvantage is that it can be quite noisy and slow. Two limitations that will
be solved are that it does not work with bump mapping yet, and that the falloff
function used is a simple cubic function, it's not using the real BSSRDF
falloff function yet.

The node has a color input, along with a scattering radius for each RGB color
channel along with an overall scale factor for the radii.

There is also no GPU support yet, will test if I can get that working later.

Node Documentation:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#BSSRDF

Implementation notes:
http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/Subsurface_Scattering

7 files changed, 79 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index fc1cd6e45d5..1d94c1a0b8a 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -752,6 +752,7 @@ struct ShadeResult;
 #define SH_NODE_TANGENT					174
 #define SH_NODE_NORMAL_MAP				175
 #define SH_NODE_HAIR_INFO				176
+#define SH_NODE_SUBSURFACE_SCATTERING	177
 
 /* custom defines options for Material node */
 #define SH_NODE_MAT_DIFF   1
diff --git a/source/blender/blenkernel/intern/node.c b/source/blender/blenkernel/intern/node.c
index 5cf8758aa1b..b6fa1dacd0f 100644
--- a/source/blender/blenkernel/intern/node.c
+++ b/source/blender/blenkernel/intern/node.c
@@ -3438,6 +3438,7 @@ static void registerShaderNodes(void)
 	register_node_type_sh_holdout();
 	//register_node_type_sh_volume_transparent();
 	//register_node_type_sh_volume_isotropic();
+	register_node_type_sh_subsurface_scattering();
 	register_node_type_sh_mix_shader();
 	register_node_type_sh_add_shader();
 
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index 147d002475b..08747b19df2 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2074,6 +2074,11 @@ void node_bsdf_velvet(vec4 color, float sigma, vec3 N, out vec4 result)
 	node_bsdf_diffuse(color, 0.0, N, result);
 }
 
+void node_subsurface_scattering(vec4 color, float roughness, vec3 N, out vec4 result)
+{
+	node_bsdf_diffuse(color, 0.0, N, result);
+}
+
 /* emission */
 
 void node_emission(vec4 color, float strength, vec3 N, out vec4 result)
diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index f3b3d6b1f53..f2ce9665e2b 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -175,6 +175,7 @@ set(SRC
 	shader/nodes/node_shader_output_world.c
 	shader/nodes/node_shader_particle_info.c
 	shader/nodes/node_shader_script.c
+	shader/nodes/node_shader_subsurface_scattering.c
 	shader/nodes/node_shader_tangent.c
 	shader/nodes/node_shader_tex_brick.c
 	shader/nodes/node_shader_tex_checker.c
diff --git a/source/blender/nodes/NOD_shader.h b/source/blender/nodes/NOD_shader.h
index 9561fe00409..eb324182e39 100644
--- a/source/blender/nodes/NOD_shader.h
+++ b/source/blender/nodes/NOD_shader.h
@@ -101,6 +101,7 @@ void register_node_type_sh_emission(void);
 void register_node_type_sh_holdout(void);
 void register_node_type_sh_volume_transparent(void);
 void register_node_type_sh_volume_isotropic(void);
+void register_node_type_sh_subsurface_scattering(void);
 void register_node_type_sh_mix_shader(void);
 void register_node_type_sh_add_shader(void);
 
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 9d044772274..811cd3f3b4a 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -84,6 +84,7 @@ DefNode( ShaderNode,     SH_NODE_BSDF_REFRACTION,    def_glossy,             "BS
 DefNode( ShaderNode,     SH_NODE_BSDF_TRANSLUCENT,   0,                      "BSDF_TRANSLUCENT",   BsdfTranslucent,  "Translucent BSDF",  ""       )
 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_SUBSURFACE_SCATTERING, 0,                   "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
new file mode 100644
index 00000000000..cde6ec8be45
--- /dev/null
+++ b/source/blender/nodes/shader/nodes/node_shader_subsurface_scattering.c
@@ -0,0 +1,69 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version. 
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2005 Blender Foundation.
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): none yet.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#include "../node_shader_util.h"
+
+/* **************** 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, 1000000.0f},
+	{	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},
+	{	-1, 0, ""	}
+};
+
+static bNodeSocketTemplate sh_node_subsurface_scattering_out[] = {
+	{	SOCK_SHADER, 0, N_("BSSRDF")},
+	{	-1, 0, ""	}
+};
+
+static int node_shader_gpu_subsurface_scattering(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
+{
+	if (!in[1].link)
+		in[1].link = GPU_builtin(GPU_VIEW_NORMAL);
+
+	return GPU_stack_link(mat, "node_subsurface_scattering", in, out);
+}
+
+/* node type definition */
+void register_node_type_sh_subsurface_scattering(void)
+{
+	static bNodeType ntype;
+
+	sh_node_type_base(&ntype, SH_NODE_SUBSURFACE_SCATTERING, "Subsurface Scattering", NODE_CLASS_SHADER, 0);
+	node_type_compatibility(&ntype, NODE_NEW_SHADING);
+	node_type_socket_templates(&ntype, sh_node_subsurface_scattering_in, sh_node_subsurface_scattering_out);
+	node_type_size(&ntype, 150, 60, 200);
+	node_type_init(&ntype, NULL);
+	node_type_storage(&ntype, "", NULL, NULL);
+	node_type_gpu(&ntype, node_shader_gpu_subsurface_scattering);
+
+	nodeRegisterType(&ntype);
+}
+