Modifiers: UVWarp modifier add invert vgroup option

Adds the invert vgroup option to the UVWarp modifier. Adds a flag and char padding to the DNA.

Differential Revision: https://developer.blender.org/D6841

4 files changed, 20 insertions, 3 deletions

diff --git a/release/scripts/startup/bl_ui/properties_data_modifier.py b/release/scripts/startup/bl_ui/properties_data_modifier.py
index ffd42c452f0..5028c78f4c3 100644
--- a/release/scripts/startup/bl_ui/properties_data_modifier.py
+++ b/release/scripts/startup/bl_ui/properties_data_modifier.py
@@ -1479,7 +1479,9 @@ class DATA_PT_modifiers(ModifierButtonsPanel, Panel):
 
         col = split.column()
         col.label(text="Vertex Group:")
-        col.prop_search(md, "vertex_group", ob, "vertex_groups", text="")
+        row = col.row(align=True)
+        row.prop_search(md, "vertex_group", ob, "vertex_groups", text="")
+        row.prop(md, "invert_vertex_group", text="", icon='ARROW_LEFTRIGHT')
 
         col = split.column()
         col.label(text="UV Map:")
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 2abe1b38a8d..2d625e7006b 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -1743,7 +1743,7 @@ typedef struct UVWarpModifierData {
   ModifierData modifier;
 
   char axis_u, axis_v;
-  char _pad[2];
+  short flag;
   /** Used for rotate/scale. */
   float center[2];
 
@@ -1766,6 +1766,11 @@ typedef struct UVWarpModifierData {
   char uvlayer_name[64];
 } UVWarpModifierData;
 
+/* UVWarp modifier flags */
+enum {
+  MOD_UVWARP_INVERT_VGROUP = 1 << 0,
+};
+
 /* cache modifier */
 typedef struct MeshCacheModifierData {
   ModifierData modifier;
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 24b7c968707..9a4048e6aaa 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -4659,6 +4659,11 @@ static void rna_def_modifier_uvwarp(BlenderRNA *brna)
   RNA_def_property_string_funcs(prop, NULL, NULL, "rna_UVWarpModifier_vgroup_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_UVWARP_INVERT_VGROUP);
+  RNA_def_property_ui_text(prop, "Invert", "Invert vertex group influence");
+  RNA_def_property_update(prop, 0, "rna_Modifier_update");
+
   prop = RNA_def_property(srna, "uv_layer", PROP_STRING, PROP_NONE);
   RNA_def_property_string_sdna(prop, NULL, "uvlayer_name");
   RNA_def_property_ui_text(prop, "UV Layer", "UV Layer name");
diff --git a/source/blender/modifiers/intern/MOD_uvwarp.c b/source/blender/modifiers/intern/MOD_uvwarp.c
index 2dfb9031c38..973923d1cf4 100644
--- a/source/blender/modifiers/intern/MOD_uvwarp.c
+++ b/source/blender/modifiers/intern/MOD_uvwarp.c
@@ -88,6 +88,7 @@ typedef struct UVWarpData {
   int defgrp_index;
 
   float (*warp_mat)[4];
+  bool invert_vgroup;
 } UVWarpData;
 
 static void uv_warp_compute(void *__restrict userdata,
@@ -110,7 +111,9 @@ static void uv_warp_compute(void *__restrict userdata,
   if (dvert) {
     for (l = 0; l < mp->totloop; l++, ml++, mluv++) {
       float uv[2];
-      const float weight = defvert_find_weight(&dvert[ml->v], defgrp_index);
+      const float weight = data->invert_vgroup ?
+                               1.0f - defvert_find_weight(&dvert[ml->v], defgrp_index) :
+                               defvert_find_weight(&dvert[ml->v], defgrp_index);
 
       uv_warp_from_mat4_pair(uv, mluv->uv, warp_mat);
       interp_v2_v2v2(mluv->uv, mluv->uv, uv, weight);
@@ -136,6 +139,7 @@ static Mesh *applyModifier(ModifierData *md, const ModifierEvalContext *ctx, Mes
   float warp_mat[4][4];
   const int axis_u = umd->axis_u;
   const int axis_v = umd->axis_v;
+  const bool invert_vgroup = (umd->flag & MOD_UVWARP_INVERT_VGROUP) != 0;
 
   /* make sure there are UV Maps available */
   if (!CustomData_has_layer(&mesh->ldata, CD_MLOOPUV)) {
@@ -208,6 +212,7 @@ static Mesh *applyModifier(ModifierData *md, const ModifierEvalContext *ctx, Mes
       .dvert = dvert,
       .defgrp_index = defgrp_index,
       .warp_mat = warp_mat,
+      .invert_vgroup = invert_vgroup,
   };
   TaskParallelSettings settings;
   BLI_parallel_range_settings_defaults(&settings);