Fix T43149: Grease Pencil fill areas look divided by multiples ray lines

The problem here was caused by the usage of GL_POLYGON_SMOOTH (thanks Campbell
for the help tracking this down!). Apparently the issue is that this option
ends up doing some nasty accumulation with whatever is in the framebuffer for
each *tesselated* polygon (instead of the whole polygon as intended/expected).

** IMPORTANT USER NOTES **
With the removal of this option, filled areas and volumetric strokes will now
have jagged edges again. To resolve these artifacts, it is necessary to enable
Viewport Multisampling (found in the User Preferences, under the System tab),
and restart Blender to see the effects of this change.

1 files changed, 4 insertions, 3 deletions

diff --git a/source/blender/editors/gpencil/drawgpencil.c b/source/blender/editors/gpencil/drawgpencil.c
index 895fc6608e2..20279caaf7c 100644
--- a/source/blender/editors/gpencil/drawgpencil.c
+++ b/source/blender/editors/gpencil/drawgpencil.c
@@ -1051,8 +1051,10 @@ static void gp_draw_data(bGPdata *gpd, int offsx, int offsy, int winx, int winy,
 	/* turn on smooth lines (i.e. anti-aliasing) */
 	glEnable(GL_LINE_SMOOTH);
 	
-	glEnable(GL_POLYGON_SMOOTH);
-	glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
+	/* XXX: turn on some way of ensuring that the polygon edges get smoothed 
+	 *      GL_POLYGON_SMOOTH is nasty and shouldn't be used, as it ends up
+	 *      creating internal white rays due to the ways it accumulates stuff
+	 */
 	
 	/* turn on alpha-blending */
 	glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
@@ -1064,7 +1066,6 @@ static void gp_draw_data(bGPdata *gpd, int offsx, int offsy, int winx, int winy,
 	/* turn off alpha blending, then smooth lines */
 	glDisable(GL_BLEND); // alpha blending
 	glDisable(GL_LINE_SMOOTH); // smooth lines
-	glDisable(GL_POLYGON_SMOOTH); // smooth poly lines
 	
 	/* restore initial gl conditions */
 	glLineWidth(1.0);