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

1 files changed, 24 insertions, 13 deletions

diff --git a/intern/cycles/kernel/osl/osl_shader.cpp b/intern/cycles/kernel/osl/osl_shader.cpp
index dedda1dc10e..23be0acb4d3 100644
--- a/intern/cycles/kernel/osl/osl_shader.cpp
+++ b/intern/cycles/kernel/osl/osl_shader.cpp
@@ -17,10 +17,14 @@
  */
 
 #include "kernel_compat_cpu.h"
+#include "kernel_montecarlo.h"
 #include "kernel_types.h"
 #include "kernel_globals.h"
 #include "kernel_object.h"
 
+#include "closure/bsdf_diffuse.h"
+#include "closure/bssrdf.h"
+
 #include "osl_bssrdf.h"
 #include "osl_closures.h"
 #include "osl_globals.h"
@@ -136,7 +140,7 @@ static void shaderdata_to_shaderglobals(KernelGlobals *kg, ShaderData *sd,
 
 /* Surface */
 
-static void flatten_surface_closure_tree(ShaderData *sd, bool no_glossy,
+static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
                                          const OSL::ClosureColor *closure, float3 weight = make_float3(1.0f, 1.0f, 1.0f))
 {
 	/* OSL gives us a closure tree, we flatten it into arrays per
@@ -156,8 +160,11 @@ static void flatten_surface_closure_tree(ShaderData *sd, bool no_glossy,
 					int scattering = bsdf->scattering();
 
 					/* no caustics option */
-					if (no_glossy && scattering == LABEL_GLOSSY)
-						return;
+					if(scattering == LABEL_GLOSSY && (path_flag & PATH_RAY_DIFFUSE)) {
+						KernelGlobals *kg = sd->osl_globals;
+						if(kernel_data.integrator.no_caustics)
+							return;
+					}
 
 					/* sample weight */
 					float sample_weight = fabsf(average(weight));
@@ -230,26 +237,32 @@ static void flatten_surface_closure_tree(ShaderData *sd, bool no_glossy,
 						sc.data1 = bssrdf->sc.data1;
 						sc.prim = NULL;
 
+						/* disable in case of diffuse ancestor, can't see it well then and
+						 * adds considerably noise due to probabilities of continuing path
+						 * getting lower and lower */
+						if(sc.type != CLOSURE_BSSRDF_COMPATIBLE_ID && (path_flag & PATH_RAY_DIFFUSE_ANCESTOR))
+							bssrdf->radius = make_float3(0.0f, 0.0f, 0.0f);
+
 						/* create one closure for each color channel */
 						if(fabsf(weight.x) > 0.0f) {
 							sc.weight = make_float3(weight.x, 0.0f, 0.0f);
 							sc.data0 = bssrdf->radius.x;
+							sd->flag |= bssrdf_setup(&sc, sc.type);
 							sd->closure[sd->num_closure++] = sc;
-							sd->flag |= bssrdf->shaderdata_flag();
 						}
 
 						if(fabsf(weight.y) > 0.0f) {
 							sc.weight = make_float3(0.0f, weight.y, 0.0f);
 							sc.data0 = bssrdf->radius.y;
+							sd->flag |= bssrdf_setup(&sc, sc.type);
 							sd->closure[sd->num_closure++] = sc;
-							sd->flag |= bssrdf->shaderdata_flag();
 						}
 
 						if(fabsf(weight.z) > 0.0f) {
 							sc.weight = make_float3(0.0f, 0.0f, weight.z);
 							sc.data0 = bssrdf->radius.z;
+							sd->flag |= bssrdf_setup(&sc, sc.type);
 							sd->closure[sd->num_closure++] = sc;
-							sd->flag |= bssrdf->shaderdata_flag();
 						}
 					}
 					break;
@@ -264,12 +277,12 @@ static void flatten_surface_closure_tree(ShaderData *sd, bool no_glossy,
 	}
 	else if (closure->type == OSL::ClosureColor::MUL) {
 		OSL::ClosureMul *mul = (OSL::ClosureMul *)closure;
-		flatten_surface_closure_tree(sd, no_glossy, mul->closure, TO_FLOAT3(mul->weight) * weight);
+		flatten_surface_closure_tree(sd, path_flag, mul->closure, TO_FLOAT3(mul->weight) * weight);
 	}
 	else if (closure->type == OSL::ClosureColor::ADD) {
 		OSL::ClosureAdd *add = (OSL::ClosureAdd *)closure;
-		flatten_surface_closure_tree(sd, no_glossy, add->closureA, weight);
-		flatten_surface_closure_tree(sd, no_glossy, add->closureB, weight);
+		flatten_surface_closure_tree(sd, path_flag, add->closureA, weight);
+		flatten_surface_closure_tree(sd, path_flag, add->closureB, weight);
 	}
 }
 
@@ -292,10 +305,8 @@ void OSLShader::eval_surface(KernelGlobals *kg, ShaderData *sd, float randb, int
 	sd->num_closure = 0;
 	sd->randb_closure = randb;
 
-	if (globals->Ci) {
-		bool no_glossy = (path_flag & PATH_RAY_DIFFUSE) && kernel_data.integrator.no_caustics;
-		flatten_surface_closure_tree(sd, no_glossy, globals->Ci);
-	}
+	if (globals->Ci)
+		flatten_surface_closure_tree(sd, path_flag, globals->Ci);
 }
 
 /* Background */