Modifiers: Laplacian Deform modifier add invert vgroup option

Adds the invert vgroup option to the Laplacian Deform modifier.

Differential Revision: https://developer.blender.org/D6843

3 files changed, 12 insertions, 2 deletions

diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 98ffe7ef416..20ea798a2fa 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -1843,6 +1843,7 @@ typedef struct LaplacianDeformModifierData {
 /* Laplacian Deform modifier flags */
 enum {
   MOD_LAPLACIANDEFORM_BIND = 1 << 0,
+  MOD_LAPLACIANDEFORM_INVERT_VGROUP = 1 << 1,
 };
 
 /* many of these options match 'solidify' */
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 0b67644a0bc..8063c5b80c4 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -5635,6 +5635,11 @@ static void rna_def_modifier_laplaciandeform(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Bound", "Whether geometry has been bound to anchors");
   RNA_def_property_clear_flag(prop, PROP_EDITABLE);
 
+  prop = RNA_def_property(srna, "invert_vertex_group", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "flag", MOD_LAPLACIANDEFORM_INVERT_VGROUP);
+  RNA_def_property_ui_text(prop, "Invert", "Invert vertex group influence");
+  RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
   RNA_def_property_update(prop, 0, "rna_Modifier_update");
 }
 
diff --git a/source/blender/modifiers/intern/MOD_laplaciandeform.c b/source/blender/modifiers/intern/MOD_laplaciandeform.c
index 866cf67bf79..f2f99b7ddfa 100644
--- a/source/blender/modifiers/intern/MOD_laplaciandeform.c
+++ b/source/blender/modifiers/intern/MOD_laplaciandeform.c
@@ -528,6 +528,7 @@ static void initSystem(
   MDeformVert *dvert = NULL;
   MDeformVert *dv = NULL;
   LaplacianSystem *sys;
+  const bool invert_vgroup = (lmd->flag & MOD_LAPLACIANDEFORM_INVERT_VGROUP) != 0;
 
   if (isValidVertexGroup(lmd, ob, mesh)) {
     int *index_anchors = MEM_malloc_arrayN(numVerts, sizeof(int), __func__); /* over-alloc */
@@ -542,7 +543,8 @@ static void initSystem(
     BLI_assert(dvert != NULL);
     dv = dvert;
     for (i = 0; i < numVerts; i++) {
-      wpaint = defvert_find_weight(dv, defgrp_index);
+      wpaint = invert_vgroup ? 1.0f - defvert_find_weight(dv, defgrp_index) :
+                               defvert_find_weight(dv, defgrp_index);
       dv++;
       if (wpaint > 0.0f) {
         STACK_PUSH(index_anchors, i);
@@ -596,6 +598,7 @@ static int isSystemDifferent(LaplacianDeformModifierData *lmd,
   MDeformVert *dvert = NULL;
   MDeformVert *dv = NULL;
   LaplacianSystem *sys = (LaplacianSystem *)lmd->cache_system;
+  const bool invert_vgroup = (lmd->flag & MOD_LAPLACIANDEFORM_INVERT_VGROUP) != 0;
 
   if (sys->total_verts != numVerts) {
     return LAPDEFORM_SYSTEM_CHANGE_VERTEXES;
@@ -612,7 +615,8 @@ static int isSystemDifferent(LaplacianDeformModifierData *lmd,
   }
   dv = dvert;
   for (i = 0; i < numVerts; i++) {
-    wpaint = defvert_find_weight(dv, defgrp_index);
+    wpaint = invert_vgroup ? 1.0f - defvert_find_weight(dv, defgrp_index) :
+                             defvert_find_weight(dv, defgrp_index);
     dv++;
     if (wpaint > 0.0f) {
       total_anchors++;