Materials: support true float4 attributes in the Attribute node.

Add a new Alpha socket to the Attribute node that outputs the
fourth component of the attribute. Currently the only such
attribute is vertex color, but there may be more in the future.
If the attribute has no alpha channel, the expected value is 1.

The Cycles code is already refactored and committed by Brecht.

Ref D2057

1 files changed, 5 insertions, 4 deletions

diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl
index 10e1b4563bc..631d91c89d6 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_attribute.glsl
@@ -1,6 +1,7 @@
-void node_attribute(vec3 attr, out vec4 outcol, out vec3 outvec, out float outf)
+void node_attribute(vec4 attr, out vec4 outcol, out vec3 outvec, out float outf, out float outalpha)
 {
-  outcol = vec4(attr, 1.0);
-  outvec = attr;
-  outf = avg(attr);
+  outcol = vec4(attr.xyz, 1.0);
+  outvec = attr.xyz;
+  outf = avg(attr.xyz);
+  outalpha = attr.w;
 }