[Bf-blender-cvs] [d7a877b] master: Fix WPaint inactive when painting on a vgroup and the only other vgroup is locked.

[Bastien Montagne]

Commit: d7a877b69ca8d2cc6c5de0691d7bdf899af165ba
Author: Bastien Montagne
Date:   Fri Feb 27 11:43:10 2015 +0100
Branches: master
https://developer.blender.org/rBd7a877b69ca8d2cc6c5de0691d7bdf899af165ba

Fix WPaint inactive when painting on a vgroup and the only other vgroup is locked.

`enforce_locks()` would reset weights of non-locked modified vgroups if it could not
find any other non-modified non-locked vgroup to 'distribute' weights into.
Sounds rather stupid, yet I hope I did not break something else, this code
is rather convoluted to say the least.

Side-reported by zeauro (ronan ducluzeau) in T43814, thanks!

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

M	source/blender/editors/sculpt_paint/paint_vertex.c

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

diff --git a/source/blender/editors/sculpt_paint/paint_vertex.c b/source/blender/editors/sculpt_paint/paint_vertex.c
index 7324ceb..e87dd6c 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex.c
@@ -1575,8 +1575,8 @@ static void enforce_locks(MDeformVert *odv, MDeformVert *ndv,
 			change_status[i] = 1; /* can be altered while redistributing */
 		}
 	}
-	/* if there was any change, redistribute it */
-	if (total_changed) {
+	/* if there was any change, and somewhere to redistribute it, do it */
+	if (total_changed && total_valid) {
 		/* auto normalize will allow weights to temporarily go above 1 in redistribution */
 		if (vgroup_validmap && total_changed < 0 && total_valid) {
 			totchange_allowed = total_valid;
@@ -1740,7 +1740,8 @@ static int apply_mp_locks_normalize(Mesh *me, const WeightPaintInfo *wpi,
 	}
 	clamp_weights(dv);
 
-	enforce_locks(&dv_test, dv, wpi->defbase_tot, wpi->defbase_sel, wpi->lock_flags, wpi->vgroup_validmap, wpi->do_auto_normalize, wpi->do_multipaint);
+	enforce_locks(&dv_test, dv, wpi->defbase_tot, wpi->defbase_sel, wpi->lock_flags, wpi->vgroup_validmap,
+	              wpi->do_auto_normalize, wpi->do_multipaint);
 
 	if (wpi->do_auto_normalize) {
 		/* XXX - should we pass the active group? - currently '-1' */