Fix T67587: Fix Drawing in Wireframe Non X-Ray Mode

When using Vertex or Weight paint mode on a wireframe the overlay was
blended with the background. In this case we now use alpha blending.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D5340

2 files changed, 12 insertions, 2 deletions

diff --git a/source/blender/draw/modes/shaders/paint_vertex_frag.glsl b/source/blender/draw/modes/shaders/paint_vertex_frag.glsl
index 426dbada812..f03e3410ec3 100644
--- a/source/blender/draw/modes/shaders/paint_vertex_frag.glsl
+++ b/source/blender/draw/modes/shaders/paint_vertex_frag.glsl
@@ -2,7 +2,7 @@
 in vec3 finalColor;
 
 out vec4 fragColor;
-uniform float white_factor = 1.0;
+uniform float opacity = 1.0;
 
 vec3 linear_to_srgb_attr(vec3 c)
 {
@@ -14,6 +14,11 @@ vec3 linear_to_srgb_attr(vec3 c)
 
 void main()
 {
-  fragColor.rgb = mix(linear_to_srgb_attr(finalColor), vec3(1.0), white_factor);
+  vec3 color = linear_to_srgb_attr(finalColor);
+#ifdef DRW_STATE_BLEND_ALPHA
+  fragColor = vec4(color, opacity);
+#else
+  fragColor.rgb = mix(vec3(1.0), color, opacity);
   fragColor.a = 1.0;
+#endif
 }
diff --git a/source/blender/draw/modes/shaders/paint_weight_frag.glsl b/source/blender/draw/modes/shaders/paint_weight_frag.glsl
index 8b0e03ac31c..76b7719be64 100644
--- a/source/blender/draw/modes/shaders/paint_weight_frag.glsl
+++ b/source/blender/draw/modes/shaders/paint_weight_frag.glsl
@@ -95,6 +95,11 @@ void main()
     color = mix(weight_color, colorVertexUnreferenced, alert * alert);
   }
 
+#ifdef DRW_STATE_BLEND_ALPHA
+  /* alpha blending mix */
+  fragColor = vec4(color.rgb, opacity);
+#else
   /* mix with 1.0 -> is like opacity when using multiply blend mode */
   fragColor = vec4(mix(vec3(1.0), color.rgb, opacity), 1.0);
+#endif
 }