New fix for [#29543] Hook modifier: falloff + vgroup influence broken

Don't know why, but creating a dm when there was none broke multi hooks on curves (see #29567)... So as a valid dm is only mandatory for meshes when a vgroup is set, only create it in those cases!

1 files changed, 13 insertions, 3 deletions

diff --git a/source/blender/modifiers/intern/MOD_hook.c b/source/blender/modifiers/intern/MOD_hook.c
index b5cf289f4ce..9948a1a462d 100644
--- a/source/blender/modifiers/intern/MOD_hook.c
+++ b/source/blender/modifiers/intern/MOD_hook.c
@@ -249,15 +249,25 @@ static void deformVerts(ModifierData *md, Object *ob, DerivedMesh *derivedData,
                         int UNUSED(useRenderParams), int UNUSED(isFinalCalc))
 {
 	HookModifierData *hmd = (HookModifierData*) md;
-	
-	deformVerts_do(hmd, ob, derivedData, vertexCos, numVerts);
+	DerivedMesh *dm = derivedData;
+	/* We need a valid dm for meshes when a vgroup is set... */
+	if(!dm && ob->type == OB_MESH && hmd->name[0] != '\0')
+		dm = get_dm(ob, NULL, dm, NULL, 0);
+
+	deformVerts_do(hmd, ob, dm, vertexCos, numVerts);
+
+	if(derivedData != dm)
+		dm->release(dm);
 }
 
 static void deformVertsEM(ModifierData *md, Object *ob, struct EditMesh *editData,
                           DerivedMesh *derivedData, float (*vertexCos)[3], int numVerts)
 {
 	HookModifierData *hmd = (HookModifierData*) md;
-	DerivedMesh *dm = get_dm(ob, editData, derivedData, NULL, 0);
+	DerivedMesh *dm = derivedData;
+	/* We need a valid dm for meshes when a vgroup is set... */
+	if(!dm && ob->type == OB_MESH && hmd->name[0] != '\0')
+		dm = get_dm(ob, editData, dm, NULL, 0);
 
 	deformVerts_do(hmd, ob, dm, vertexCos, numVerts);