Cycles: fix for ColorRamp node alpha output.

2 files changed, 12 insertions, 3 deletions

diff --git a/intern/cycles/kernel/svm/svm_ramp.h b/intern/cycles/kernel/svm/svm_ramp.h
index 0654240c21b..55c2b3f6af4 100644
--- a/intern/cycles/kernel/svm/svm_ramp.h
+++ b/intern/cycles/kernel/svm/svm_ramp.h
@@ -40,11 +40,15 @@ __device void svm_node_rgb_ramp(KernelGlobals *kg, ShaderData *sd, float *stack,
 {
 	uint fac_offset = node.y;
 	uint color_offset = node.z;
+	uint alpha_offset = node.w;
 
 	float fac = stack_load_float(stack, fac_offset);
 	float4 color = rgb_ramp_lookup(kg, *offset, fac);
 
-	stack_store_float3(stack, color_offset, float4_to_float3(color));
+	if(stack_valid(color_offset))
+		stack_store_float3(stack, color_offset, float4_to_float3(color));
+	if(stack_valid(alpha_offset))
+		stack_store_float(stack, alpha_offset, color.w);
 
 	*offset += RAMP_TABLE_SIZE;
 }
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index 45ba18469d6..db696993737 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -2388,17 +2388,22 @@ RGBRampNode::RGBRampNode()
 {
 	add_input("Fac", SHADER_SOCKET_FLOAT);
 	add_output("Color", SHADER_SOCKET_COLOR);
+	add_output("Alpha", SHADER_SOCKET_FLOAT);
 }
 
 void RGBRampNode::compile(SVMCompiler& compiler)
 {
 	ShaderInput *fac_in = input("Fac");
 	ShaderOutput *color_out = output("Color");
+	ShaderOutput *alpha_out = output("Alpha");
 
 	compiler.stack_assign(fac_in);
-	compiler.stack_assign(color_out);
+	if(!color_out->links.empty())
+		compiler.stack_assign(color_out);
+	if(!alpha_out->links.empty())
+		compiler.stack_assign(alpha_out);
 
-	compiler.add_node(NODE_RGB_RAMP, fac_in->stack_offset, color_out->stack_offset);
+	compiler.add_node(NODE_RGB_RAMP, fac_in->stack_offset, color_out->stack_offset, alpha_out->stack_offset);
 	compiler.add_array(ramp, RAMP_TABLE_SIZE);
 }