Cycles / Shader graph: Fallback to Sharp closures for very small roughness.

We fallback to Sharp closures for Glossy, Glass and Refraction nodes now, in case the Roughness input is disconnected and 0 (< 1e-4f to be exact).
This way we gain a few percentages of performance, in case the user did not manually set the closure type to "Sharp" in the UI.

Sharp will probably be removed from the UI as a followup, not needed anymore with this internal optimization.

Original idea by Lukas Stockner(Differential Revision: https://developer.blender.org/D1439), code implementation by myself.

1 files changed, 2 insertions, 0 deletions

diff --git a/intern/cycles/render/graph.h b/intern/cycles/render/graph.h
index 8169e606f1a..fa2de3703c0 100644
--- a/intern/cycles/render/graph.h
+++ b/intern/cycles/render/graph.h
@@ -196,6 +196,7 @@ public:
 	virtual void attributes(Shader *shader, AttributeRequestSet *attributes);
 	virtual void compile(SVMCompiler& compiler) = 0;
 	virtual void compile(OSLCompiler& compiler) = 0;
+	virtual void optimize() {};
 
 	virtual bool has_surface_emission() { return false; }
 	virtual bool has_surface_transparent() { return false; }
@@ -275,6 +276,7 @@ public:
 	void relink(vector<ShaderInput*> inputs, vector<ShaderInput*> outputs, ShaderOutput *output);
 
 	void remove_unneeded_nodes();
+	void simplify_nodes();
 	void finalize(bool do_bump = false, bool do_osl = false);
 
 	int get_num_closures();