Cycles: Add method to dump current shader graph to the graphiz file

This is rather useful to see how good optimization went and so.

Currently uses quite simple notation: shader nodes are nodes on the
graph, connects between graph nodes are named by the sockets names,
so i.e. connection between BSDF and Mix would be named bsdf:closure1.

Could be improved in the feature to draw fancier graph, but it's good
enough already.

Use in the following way:
- To create graphix file call graph->dump_graph("graph.dot")
- To visualize the grapf call: dot -Tpng graph.dot -o graph.png

1 files changed, 2 insertions, 0 deletions

diff --git a/intern/cycles/render/graph.h b/intern/cycles/render/graph.h
index 7bfd51cdee3..7b95703d3aa 100644
--- a/intern/cycles/render/graph.h
+++ b/intern/cycles/render/graph.h
@@ -250,6 +250,8 @@ public:
 	void remove_unneeded_nodes();
 	void finalize(bool do_bump = false, bool do_osl = false);
 
+	void dump_graph(const char *filename);
+
 protected:
 	typedef pair<ShaderNode* const, ShaderNode*> NodePair;