Cycles: Refactor of constant fold.

* Move constant folding from nodes to the shader graph. This way it's part of our (later) 4-step optimization process.
* Instead of only doing a one level constant fold, we can now do a recursive constant fold, allowing us to simplify shaders much further.
Constant folding is implemented for Blackbody, Math and VectorMath nodes.

Example (the highlighted nodes are removed before rendering):
Before: http://archive.dingto.org/2015/blender/code/one_level_constant_fold.jpg
Now: http://archive.dingto.org/2015/blender/code/multi_level_constant_fold.jpg

Thanks to Sergey and Brecht for Review!
Differential Revision: https://developer.blender.org/D1626

1 files changed, 6 insertions, 3 deletions

diff --git a/intern/cycles/render/nodes.h b/intern/cycles/render/nodes.h
index 4f4061286cb..259936c0b7c 100644
--- a/intern/cycles/render/nodes.h
+++ b/intern/cycles/render/nodes.h
@@ -311,7 +311,7 @@ class GlossyBsdfNode : public BsdfNode {
 public:
 	SHADER_NODE_CLASS(GlossyBsdfNode)
 
-	void optimize(Scene *scene);
+	void simplify_settings(Scene *scene);
 	bool has_integrator_dependency();
 
 	ustring distribution, distribution_orig;
@@ -322,7 +322,7 @@ class GlassBsdfNode : public BsdfNode {
 public:
 	SHADER_NODE_CLASS(GlassBsdfNode)
 
-	void optimize(Scene *scene);
+	void simplify_settings(Scene *scene);
 	bool has_integrator_dependency();
 
 	ustring distribution, distribution_orig;
@@ -333,7 +333,7 @@ class RefractionBsdfNode : public BsdfNode {
 public:
 	SHADER_NODE_CLASS(RefractionBsdfNode)
 
-	void optimize(Scene *scene);
+	void simplify_settings(Scene *scene);
 	bool has_integrator_dependency();
 
 	ustring distribution, distribution_orig;
@@ -636,6 +636,7 @@ public:
 class BlackbodyNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(BlackbodyNode)
+	bool constant_fold(ShaderOutput *socket, float3 *optimized_value);
 
 	virtual int get_group() { return NODE_GROUP_LEVEL_3; }
 };
@@ -644,6 +645,7 @@ class MathNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(MathNode)
 	virtual int get_group() { return NODE_GROUP_LEVEL_1; }
+	bool constant_fold(ShaderOutput *socket, float3 *optimized_value);
 
 	bool use_clamp;
 
@@ -663,6 +665,7 @@ class VectorMathNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(VectorMathNode)
 	virtual int get_group() { return NODE_GROUP_LEVEL_1; }
+	bool constant_fold(ShaderOutput *socket, float3 *optimized_value);
 
 	ustring type;
 	static ShaderEnum type_enum;