Cycles: Initial work towards selective nodes support compilation

The goal is to be able to compile kernel with nodes which are actually needed
to render current scene, hence improving performance of the kernel,

The idea is:

- Have few node groups, starting with a group which contains nodes are used
  really often, and then couple of groups which will be extension of this one.

- Have feature-based nodes disabling, so it's possible to disable nodes related
  to features which are not used with the currently used nodes group.

This commit only lays down needed routines for this approach, actual split will
happen later after gathering statistics from bunch of production scenes.

4 files changed, 41 insertions, 0 deletions

diff --git a/intern/cycles/render/graph.h b/intern/cycles/render/graph.h
index 6744804ef19..e6271009999 100644
--- a/intern/cycles/render/graph.h
+++ b/intern/cycles/render/graph.h
@@ -207,6 +207,24 @@ public:
 	ShaderBump bump; /* for bump mapping utility */
 	
 	ShaderNodeSpecialType special_type;	/* special node type */
+
+	/* ** Selective nodes compilation ** */
+
+	/* TODO(sergey): More explicitly mention in the function names
+	 * that those functions are for selective compilation only?
+	 */
+
+	/* Nodes are split into several groups, group of level 0 contains
+	 * nodes which are most commonly used, further levels are extension
+	 * of previous one and includes less commonly used nodes.
+	 */
+	virtual int get_group() { return NODE_GROUP_LEVEL_0; }
+
+	/* Node feature are used to disable huge nodes inside the group,
+	 * so it's possible to disable huge nodes inside of the required
+	 * nodes group.
+	 */
+	virtual int get_feature() { return 0; }
 };
 
 
diff --git a/intern/cycles/render/nodes.h b/intern/cycles/render/nodes.h
index 686fb5e2fd7..ac7bbaf3547 100644
--- a/intern/cycles/render/nodes.h
+++ b/intern/cycles/render/nodes.h
@@ -415,6 +415,7 @@ public:
 
 	void attributes(Shader *shader, AttributeRequestSet *attributes);
 	bool has_spatial_varying() { return true; }
+	virtual int get_feature() { return NODE_FEATURE_HAIR; }
 };
 
 class ValueNode : public ShaderNode {
diff --git a/intern/cycles/render/shader.cpp b/intern/cycles/render/shader.cpp
index 971cd5097de..2eaba3fa786 100644
--- a/intern/cycles/render/shader.cpp
+++ b/intern/cycles/render/shader.cpp
@@ -480,5 +480,24 @@ void ShaderManager::add_default(Scene *scene)
 	}
 }
 
+void ShaderManager::get_requested_features(Scene *scene, int& max_group, int& features)
+{
+	max_group = NODE_GROUP_LEVEL_0;
+	features = 0;
+	for(int i = 0; i < scene->shaders.size(); i++) {
+		Shader *shader = scene->shaders[i];
+		foreach(ShaderNode *node, shader->graph->nodes) {
+			max_group = min(max_group, node->get_group());
+			features |= node->get_feature();
+			if(node->special_type == SHADER_SPECIAL_TYPE_CLOSURE) {
+				BsdfNode *bsdf_node = static_cast<BsdfNode*>(node);
+				if(CLOSURE_IS_VOLUME(bsdf_node->closure)) {
+					features |= NODE_FEATURE_VOLUME;
+				}
+			}
+		}
+	}
+}
+
 CCL_NAMESPACE_END
 
diff --git a/intern/cycles/render/shader.h b/intern/cycles/render/shader.h
index 5bcb2c4e344..27b239601d0 100644
--- a/intern/cycles/render/shader.h
+++ b/intern/cycles/render/shader.h
@@ -165,6 +165,9 @@ public:
 	 * have any shader assigned explicitly */
 	static void add_default(Scene *scene);
 
+	/* Selective nodes compilation. */
+	void get_requested_features(Scene *scene, int& max_group, int& features);
+
 protected:
 	ShaderManager();