[Bf-blender-cvs] [26df95cff66] blender2.8: GP: Make Multiply blend works with opacity

[Antonioya]

Commit: 26df95cff6620f17d6631c83efe05177b7a90e87
Author: Antonioya
Date:   Mon Nov 26 22:19:46 2018 +0100
Branches: blender2.8
https://developer.blender.org/rB26df95cff6620f17d6631c83efe05177b7a90e87

GP: Make Multiply blend works with opacity

===================================================================

M	source/blender/draw/engines/gpencil/shaders/gpencil_blend_frag.glsl

===================================================================

diff --git a/source/blender/draw/engines/gpencil/shaders/gpencil_blend_frag.glsl b/source/blender/draw/engines/gpencil/shaders/gpencil_blend_frag.glsl
index 2ba02beecdb..8eeb0b8bc7f 100644
--- a/source/blender/draw/engines/gpencil/shaders/gpencil_blend_frag.glsl
+++ b/source/blender/draw/engines/gpencil/shaders/gpencil_blend_frag.glsl
@@ -58,7 +58,8 @@ vec4 get_blend_color(int mode, vec4 src_color, vec4 blend_color)
 		outcolor.a = clamp(src_color.a - (mix_color.a * blend_opacity), 0.0, 1.0);
 	}
 	else if (mode == MODE_MULTIPLY)	{
-		mix_color.rgb = mix_color.rgb * mix_color.a * blend_opacity;
+		/* interpolate between 1 and color using opacity */
+		mix_color.rgb = mix(vec3(1,1,1), mix_color.rgb * mix_color.a, blend_opacity);
 		outcolor = src_color * mix_color;
 		outcolor.a = src_color.a;
 	}