Cycles: Fold Value and RGB node as well.

This way, connecting Value or RGB node to e.g. a Math node will still allow folding.

Note: The same should be done for the ConvertNode, but I leave that for another day.

intern/cycles/render/graph.cpp

@@ -617,7 +617,7 @@ void ShaderGraph::constant_fold()
 			 */
 			foreach(ShaderInput *input, output->links) {
 				if(scheduled.find(input->parent) != scheduled.end()) {
-					/* Node might be not yet optimized but scheduled already
+					/* Node might not be optimized yet but scheduled already
 					 * by other dependencies. No need to re-schedule it.
 					 */
 					continue;

intern/cycles/render/nodes.cpp

@@ -3177,6 +3177,13 @@ ValueNode::ValueNode()
 	add_output("Value", SHADER_SOCKET_FLOAT);
 }
 
+bool ValueNode::constant_fold(ShaderOutput *socket, float3 *optimized_value)
+{
+	*optimized_value = make_float3(value, value, value);
+
+	return true;
+}
+
 void ValueNode::compile(SVMCompiler& compiler)
 {
 	ShaderOutput *val_out = output("Value");
@@ -3201,6 +3208,13 @@ ColorNode::ColorNode()
 	add_output("Color", SHADER_SOCKET_COLOR);
 }
 
+bool ColorNode::constant_fold(ShaderOutput *socket, float3 *optimized_value)
+{
+	*optimized_value = value;
+
+	return true;
+}
+
 void ColorNode::compile(SVMCompiler& compiler)
 {
 	ShaderOutput *color_out = output("Color");

intern/cycles/render/nodes.h

@@ -485,6 +485,8 @@ class ValueNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(ValueNode)
 
+	bool constant_fold(ShaderOutput *socket, float3 *optimized_value);
+
 	float value;
 };
 
@@ -492,6 +494,8 @@ class ColorNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(ColorNode)
 
+	bool constant_fold(ShaderOutput *socket, float3 *optimized_value);
+
 	float3 value;
 };