Modifiers: Weld Modifier add invert vgroup option

Adds the invert vgroup option to the weld modifier.

Differential Revision: https://developer.blender.org/D6818

3 files changed, 16 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 918b4a2a7ea..1b0b3d9e08e 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -1862,8 +1862,16 @@ typedef struct WeldModifierData {
   unsigned int max_interactions;
   /* Name of vertex group to use to mask, MAX_VGROUP_NAME. */
   char defgrp_name[64];
+
+  short flag;
+  char _pad[6];
 } WeldModifierData;
 
+/* WeldModifierData->flag */
+enum {
+  MOD_WELD_INVERT_VGROUP = (1 << 0),
+};
+
 typedef struct DataTransferModifierData {
   ModifierData modifier;
 
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index c6898120bfa..65963798e08 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -5717,6 +5717,11 @@ static void rna_def_modifier_weld(BlenderRNA *brna)
       prop, "Vertex Group", "Vertex group name for selecting the affected areas");
   RNA_def_property_string_funcs(prop, NULL, NULL, "rna_WeldModifier_defgrp_name_set");
   RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
+  prop = RNA_def_property(srna, "invert_vertex_group", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "flag", MOD_WELD_INVERT_VGROUP);
+  RNA_def_property_ui_text(prop, "Invert", "Invert vertex group influence");
+  RNA_def_property_update(prop, 0, "rna_Modifier_update");
 }
 
 static void rna_def_modifier_datatransfer(BlenderRNA *brna)
diff --git a/source/blender/modifiers/intern/MOD_weld.c b/source/blender/modifiers/intern/MOD_weld.c
index bd567c52d88..64a0667a41a 100644
--- a/source/blender/modifiers/intern/MOD_weld.c
+++ b/source/blender/modifiers/intern/MOD_weld.c
@@ -1623,6 +1623,7 @@ static Mesh *weldModifier_doWeld(WeldModifierData *wmd, const ModifierEvalContex
   const MPoly *mpoly, *mp;
   uint totvert, totedge, totloop, totpoly;
   uint i;
+  const bool invert_vgroup = (wmd->flag & MOD_WELD_INVERT_VGROUP) != 0;
 
   mvert = mesh->mvert;
   totvert = mesh->totvert;
@@ -1636,7 +1637,8 @@ static Mesh *weldModifier_doWeld(WeldModifierData *wmd, const ModifierEvalContex
       dv = &dvert[0];
       v_mask = BLI_BITMAP_NEW(totvert, __func__);
       for (i = 0; i < totvert; i++, dv++) {
-        const bool found = defvert_find_weight(dv, defgrp_index) > 0.0f;
+        const bool found = invert_vgroup ? 1.0f - defvert_find_weight(dv, defgrp_index) > 0.0f :
+                                           defvert_find_weight(dv, defgrp_index) > 0.0f;
         if (found) {
           BLI_BITMAP_ENABLE(v_mask, i);
           v_mask_act++;