UI: Make the grid alpha themable

Now that the 3d grid is infinite, antialiased, not occluded, and overlaid
on top of rendered view, being able to decrease its opacity to reduce
visual strain is a must.

1 files changed, 4 insertions, 3 deletions

diff --git a/source/blender/draw/modes/shaders/object_grid_frag.glsl b/source/blender/draw/modes/shaders/object_grid_frag.glsl
index 928db048a46..3ccb10ca4ab 100644
--- a/source/blender/draw/modes/shaders/object_grid_frag.glsl
+++ b/source/blender/draw/modes/shaders/object_grid_frag.glsl
@@ -172,9 +172,10 @@ void main()
 		float gridB = get_grid(grid_pos, grid_fwidth, scaleB);
 		float gridC = get_grid(grid_pos, grid_fwidth, scaleC);
 
-		FragColor = vec4(colorGrid.rgb, gridA * blend);
-		FragColor = mix(FragColor, vec4(mix(colorGrid.rgb, colorGridEmphasise.rgb, blend), 1.0), gridB);
-		FragColor = mix(FragColor, vec4(colorGridEmphasise.rgb, 1.0), gridC);
+		FragColor = colorGrid;
+		FragColor.a *= gridA * blend;
+		FragColor = mix(FragColor, mix(colorGrid, colorGridEmphasise, blend), gridB);
+		FragColor = mix(FragColor, colorGridEmphasise, gridC);
 	}
 	else {
 		FragColor = vec4(colorGrid.rgb, 0.0);