Workbench: Support Active Vertex Color

Currently it is not possible to view the vertex colors of an object. To
optimize the workflow, workbench will need to support Vertex Colors.

The Vertex Colors is a new option in `shading->color_type`. When objects
do not have vertex color, the objects will be rendered with the
`V3D_SHADING_OBJECT_COLOR`.

In order to support vertex colors in workbench the current texture/solid
shading structure is migrated to a primary shaders and fallback shaders.

Fix: T57000

Reviewers: brecht, fclem

Differential Revision: https://developer.blender.org/D4694

1 files changed, 6 insertions, 1 deletions

diff --git a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
index e654141df5c..5eff0b41e20 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
@@ -25,6 +25,9 @@ in vec3 normal_viewport;
 #ifdef V3D_SHADING_TEXTURE_COLOR
 in vec2 uv_interp;
 #endif
+#ifdef V3D_SHADING_VERTEX_COLOR
+in vec3 vertexColor;
+#endif
 #ifdef V3D_LIGHTING_MATCAP
 uniform sampler2D matcapImage;
 #endif
@@ -42,11 +45,13 @@ void main()
 {
   vec4 diffuse_color;
 
-#ifdef V3D_SHADING_TEXTURE_COLOR
+#if defined(V3D_SHADING_TEXTURE_COLOR)
   diffuse_color = workbench_sample_texture(image, uv_interp, imageSrgb, imageNearest);
   if (diffuse_color.a < ImageTransparencyCutoff) {
     discard;
   }
+#elif defined(V3D_SHADING_VERTEX_COLOR)
+  diffuse_color = vec4(vertexColor, 1.0);
 #else
   diffuse_color = vec4(materialDiffuseColor, 1.0);
 #endif /* V3D_SHADING_TEXTURE_COLOR */