[Bf-blender-cvs] [bbf810f9697] blender2.8: DRW: Fix incorrect blending functions.

[Clément Foucault]

Commit: bbf810f96976692abed26cbde897a1e10f11683e
Author: Clément Foucault
Date:   Wed Jan 3 13:25:46 2018 +0100
Branches: blender2.8
https://developer.blender.org/rBbbf810f96976692abed26cbde897a1e10f11683e

DRW: Fix incorrect blending functions.

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

M	source/blender/draw/intern/draw_manager.c

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

diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index ddf8405d67f..c6337367ee1 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -1608,7 +1608,8 @@ static void drw_state_set(DRWState state)
 				glEnable(GL_BLEND);
 
 				if ((state & DRW_STATE_BLEND) != 0) {
-					glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+					glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, /* RGB */
+					                    GL_ONE, GL_ONE_MINUS_SRC_ALPHA); /* Alpha */
 				}
 				else if ((state & DRW_STATE_MULTIPLY) != 0) {
 					glBlendFunc(GL_DST_COLOR, GL_ZERO);
@@ -1617,7 +1618,9 @@ static void drw_state_set(DRWState state)
 					glBlendFunc(GL_ONE, GL_SRC_ALPHA);
 				}
 				else if ((state & DRW_STATE_ADDITIVE) != 0) {
-					glBlendFunc(GL_SRC_ALPHA, GL_ONE);
+					/* Do not let alpha accumulate but premult the source RGB by it. */
+					glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE, /* RGB */
+					                    GL_ZERO, GL_ONE); /* Alpha */
 				}
 				else {
 					BLI_assert(0);