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

1 files changed, 90 insertions, 0 deletions

diff --git a/intern/cycles/kernel/osl/osl_bssrdf.cpp b/intern/cycles/kernel/osl/osl_bssrdf.cpp
new file mode 100644
index 00000000000..ba9b13126ac
--- /dev/null
+++ b/intern/cycles/kernel/osl/osl_bssrdf.cpp
@@ -0,0 +1,90 @@
+/*
+ * Adapted from Open Shading Language with this license:
+ *
+ * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
+ * All Rights Reserved.
+ *
+ * Modifications Copyright 2011, Blender Foundation.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * * Neither the name of Sony Pictures Imageworks nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <OpenImageIO/fmath.h>
+
+#include <OSL/genclosure.h>
+
+#include "osl_bssrdf.h"
+#include "osl_closures.h"
+
+#include "kernel_types.h"
+#include "kernel_montecarlo.h"
+
+#include "closure/bsdf_diffuse.h"
+#include "closure/bssrdf.h"
+
+CCL_NAMESPACE_BEGIN
+
+using namespace OSL;
+
+class BSSRDFClosure : public CBSSRDFClosure {
+public:
+	size_t memsize() const { return sizeof(*this); }
+	const char *name() const { return "bssrdf_cubic"; }
+
+	void setup()
+	{
+		sc.prim = NULL;
+		sc.data0 = fabsf(average(radius));
+		sc.data1 = 1.3f;
+
+		m_shaderdata_flag = bssrdf_setup(&sc);
+	}
+
+	bool mergeable(const ClosurePrimitive *other) const
+	{
+		return false;
+	}
+
+	void print_on(std::ostream &out) const
+	{
+		out << name() << " ((" << sc.N[0] << ", " << sc.N[1] << ", " << sc.N[2] << "))";
+	}
+};
+
+ClosureParam *closure_bssrdf_params()
+{
+	static ClosureParam params[] = {
+		CLOSURE_FLOAT3_PARAM(BSSRDFClosure, sc.N),
+		CLOSURE_FLOAT3_PARAM(BSSRDFClosure, radius),
+		//CLOSURE_FLOAT_PARAM(BSSRDFClosure, sc.data1),
+	    CLOSURE_STRING_KEYPARAM("label"),
+	    CLOSURE_FINISH_PARAM(BSSRDFClosure)
+	};
+	return params;
+}
+
+CLOSURE_PREPARE(closure_bssrdf_prepare, BSSRDFClosure)
+
+CCL_NAMESPACE_END
+