[Bf-blender-cvs] [1fff3e02c2d] blender2.8: DRW: Add DRW_STATE_BLEND_PREMUL blend mode.

[Clément Foucault]

Commit: 1fff3e02c2d76488e92ca0ccba76c318a56fde37
Author: Clément Foucault
Date:   Mon Apr 23 22:58:47 2018 +0200
Branches: blender2.8
https://developer.blender.org/rB1fff3e02c2d76488e92ca0ccba76c318a56fde37

DRW: Add DRW_STATE_BLEND_PREMUL blend mode.

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

M	source/blender/draw/intern/DRW_render.h
M	source/blender/draw/intern/draw_manager_exec.c

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

diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index a9c14762a04..31046377b19 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -268,6 +268,7 @@ typedef enum {
 	DRW_STATE_TRANSMISSION  = (1 << 17),
 	DRW_STATE_CLIP_PLANES   = (1 << 18),
 	DRW_STATE_ADDITIVE_FULL = (1 << 19), /* Same as DRW_STATE_ADDITIVE but let alpha accumulate without premult. */
+	DRW_STATE_BLEND_PREMUL  = (1 << 20), /* Use that if color is already premult by alpha. */
 
 	DRW_STATE_WRITE_STENCIL    = (1 << 27),
 	DRW_STATE_STENCIL_EQUAL    = (1 << 28),
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index 9aa5efc837d..a70d80257e6 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -190,8 +190,8 @@ void drw_state_set(DRWState state)
 	{
 		int test;
 		if (CHANGED_ANY_STORE_VAR(
-		        DRW_STATE_BLEND | DRW_STATE_ADDITIVE | DRW_STATE_MULTIPLY | DRW_STATE_TRANSMISSION |
-		        DRW_STATE_ADDITIVE_FULL,
+		        DRW_STATE_BLEND | DRW_STATE_BLEND_PREMUL | DRW_STATE_ADDITIVE |
+		        DRW_STATE_MULTIPLY | DRW_STATE_TRANSMISSION | DRW_STATE_ADDITIVE_FULL,
 		        test))
 		{
 			if (test) {
@@ -201,6 +201,9 @@ void drw_state_set(DRWState state)
 					glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, /* RGB */
 					                    GL_ONE, GL_ONE_MINUS_SRC_ALPHA); /* Alpha */
 				}
+				else if ((state & DRW_STATE_BLEND_PREMUL) != 0) {
+					glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
+				}
 				else if ((state & DRW_STATE_MULTIPLY) != 0) {
 					glBlendFunc(GL_DST_COLOR, GL_ZERO);
 				}