Vertex Paint: Alpha Support

GSOC 2017 by Darshan Kadu, see: D2859.

This is a partial merge of some of the features from
the soc-2017-vertex_paint branch.

- Alpha painting & drawing.
- 10 new color blending modes.
- Support for vertex select in vertex paint mode.

1 files changed, 12 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/cdderivedmesh.c b/source/blender/blenkernel/intern/cdderivedmesh.c
index e97de07752e..2ed5cc450a4 100644
--- a/source/blender/blenkernel/intern/cdderivedmesh.c
+++ b/source/blender/blenkernel/intern/cdderivedmesh.c
@@ -752,8 +752,18 @@ static void cdDM_drawMappedFaces(
 		/* avoid buffer problems in following code */
 	}
 	else if (setDrawOptions == NULL) {
+		const bool show_alpha = true;
+		if (show_alpha) {
+			glEnable(GL_BLEND);
+			glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+		}
+
 		/* just draw the entire face array */
 		GPU_buffer_draw_elements(dm->drawObject->triangles, GL_TRIANGLES, 0, tot_tri_elem);
+
+		if (show_alpha) {
+			glDisable(GL_BLEND);
+		}
 	}
 	else {
 		for (mat_index = 0; mat_index < dm->drawObject->totmaterial; mat_index++) {
@@ -1525,8 +1535,8 @@ static void cdDM_buffer_copy_mcol(
 
 	for (i = 0; i < totpoly; i++, mpoly++) {
 		for (j = 0; j < mpoly->totloop; j++) {
-			copy_v3_v3_uchar(&varray[start], &mloopcol[mpoly->loopstart + j].r);
-			start += 3;
+			copy_v4_v4_uchar(&varray[start], &mloopcol[mpoly->loopstart + j].r);
+			start += 4;
 		}
 	}
 }