1 files changed, 32 insertions, 9 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_vertex.c b/source/blender/editors/sculpt_paint/paint_vertex.c
index 9e9e0f441f7..f45c244f675 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex.c
@@ -415,7 +415,12 @@ static float wpaint_undo_lock_relative(
   /* In auto-normalize mode, or when there is no unlocked weight,
    * compute based on locked weight. */
   if (auto_normalize || free_weight <= 0.0f) {
-    weight *= (1.0f - locked_weight);
+    if (locked_weight < 1.0f - VERTEX_WEIGHT_LOCK_EPSILON) {
+      weight *= (1.0f - locked_weight);
+    }
+    else {
+      weight = 0;
+    }
   }
   else {
     /* When dealing with full unlocked weight, don't paint, as it is always displayed as 1. */
@@ -518,7 +523,7 @@ static bool do_weight_paint_normalize_all_locked(MDeformVert *dvert,
     return false;
   }
 
-  if (lock_weight >= 1.0f) {
+  if (lock_weight >= 1.0f - VERTEX_WEIGHT_LOCK_EPSILON) {
     /* locked groups make it impossible to fully normalize,
      * zero out what we can and return false */
     for (i = dvert->totweight, dw = dvert->dw; i != 0; i--, dw++) {
@@ -779,7 +784,25 @@ static void do_weight_paint_vertex_single(
     index_mirr = vgroup_mirr = -1;
   }
 
-  if (wp->flag & VP_FLAG_VGROUP_RESTRICT) {
+  /* Check if painting should create new deform weight entries. */
+  bool restrict_to_existing = (wp->flag & VP_FLAG_VGROUP_RESTRICT) != 0;
+
+  if (wpi->do_lock_relative || wpi->do_auto_normalize) {
+    /* Without do_lock_relative only dw_rel_locked is reliable, while dw_rel_free may be fake 0. */
+    dw_rel_free = BKE_defvert_total_selected_weight(dv, wpi->defbase_tot, wpi->vgroup_unlocked);
+    dw_rel_locked = BKE_defvert_total_selected_weight(dv, wpi->defbase_tot, wpi->vgroup_locked);
+    CLAMP(dw_rel_locked, 0.0f, 1.0f);
+
+    /* Do not create entries if there is not enough free weight to paint.
+     * This logic is the same as in wpaint_undo_lock_relative and auto-normalize. */
+    if (wpi->do_auto_normalize || dw_rel_free <= 0.0f) {
+      if (dw_rel_locked >= 1.0f - VERTEX_WEIGHT_LOCK_EPSILON) {
+        restrict_to_existing = true;
+      }
+    }
+  }
+
+  if (restrict_to_existing) {
     dw = BKE_defvert_find_index(dv, wpi->active.index);
   }
   else {
@@ -827,10 +850,6 @@ static void do_weight_paint_vertex_single(
 
   /* Handle weight caught up in locked defgroups for Lock Relative. */
   if (wpi->do_lock_relative) {
-    dw_rel_free = BKE_defvert_total_selected_weight(dv, wpi->defbase_tot, wpi->vgroup_unlocked);
-    dw_rel_locked = BKE_defvert_total_selected_weight(dv, wpi->defbase_tot, wpi->vgroup_locked);
-    CLAMP(dw_rel_locked, 0.0f, 1.0f);
-
     weight_cur = BKE_defvert_calc_lock_relative_weight(weight_cur, dw_rel_locked, dw_rel_free);
   }
 
@@ -1658,6 +1677,10 @@ static bool wpaint_stroke_test_start(bContext *C, wmOperator *op, const float mo
           wpd->lock_flags, wpd->vgroup_validmap, wpd->active.index) &&
       (!wpd->do_multipaint || BKE_object_defgroup_check_lock_relative_multi(
                                   defbase_tot, wpd->lock_flags, defbase_sel, defbase_tot_sel))) {
+    wpd->do_lock_relative = true;
+  }
+
+  if (wpd->do_lock_relative || (ts->auto_normalize && wpd->lock_flags && !wpd->do_multipaint)) {
     bool *unlocked = MEM_dupallocN(wpd->vgroup_validmap);
 
     if (wpd->lock_flags) {
@@ -1668,7 +1691,6 @@ static bool wpaint_stroke_test_start(bContext *C, wmOperator *op, const float mo
     }
 
     wpd->vgroup_unlocked = unlocked;
-    wpd->do_lock_relative = true;
   }
 
   if (wpd->do_multipaint && ts->auto_normalize) {
@@ -2383,7 +2405,8 @@ static void wpaint_stroke_update_step(bContext *C, struct PaintStroke *stroke, P
   wpi.vgroup_unlocked = wpd->vgroup_unlocked;
   wpi.do_flip = RNA_boolean_get(itemptr, "pen_flip");
   wpi.do_multipaint = wpd->do_multipaint;
-  wpi.do_auto_normalize = ((ts->auto_normalize != 0) && (wpi.vgroup_validmap != NULL));
+  wpi.do_auto_normalize = ((ts->auto_normalize != 0) && (wpi.vgroup_validmap != NULL) &&
+                           (wpi.do_multipaint || wpi.vgroup_validmap[wpi.active.index]));
   wpi.do_lock_relative = wpd->do_lock_relative;
   wpi.is_normalized = wpi.do_auto_normalize || wpi.do_lock_relative;
   wpi.brush_alpha_value = brush_alpha_value;