fix [#35911] Show weights not working with a weight edit modifier in edit mode

1 files changed, 15 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/DerivedMesh.c b/source/blender/blenkernel/intern/DerivedMesh.c
index aeb664b3c2f..6f86b0c3f88 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.c
+++ b/source/blender/blenkernel/intern/DerivedMesh.c
@@ -1946,9 +1946,9 @@ static void editbmesh_calc_modifiers(Scene *scene, Object *ob, BMEditMesh *em, D
                                      DerivedMesh **final_r,
                                      CustomDataMask dataMask)
 {
-	ModifierData *md;
+	ModifierData *md, *previewmd = NULL;
 	float (*deformedVerts)[3] = NULL;
-	CustomDataMask mask;
+	CustomDataMask mask, previewmask = 0;
 	DerivedMesh *dm, *orcodm = NULL;
 	int i, numVerts = 0, cageIndex = modifiers_getCageIndex(scene, ob, NULL, 1);
 	CDMaskLink *datamasks, *curr;
@@ -1962,6 +1962,7 @@ static void editbmesh_calc_modifiers(Scene *scene, Object *ob, BMEditMesh *em, D
 	const int do_final_wmcol = FALSE;
 	int do_init_wmcol = ((((Mesh *)ob->data)->drawflag & ME_DRAWEIGHT) && !do_final_wmcol);
 	int do_init_statvis = ((((Mesh *)ob->data)->drawflag & ME_DRAW_STATVIS) && !do_init_wmcol);
+	const int do_mod_wmcol = do_init_wmcol;
 
 	modifiers_clearErrors(ob);
 
@@ -1972,7 +1973,18 @@ static void editbmesh_calc_modifiers(Scene *scene, Object *ob, BMEditMesh *em, D
 	dm = NULL;
 	md = modifiers_getVirtualModifierList(ob);
 
-	datamasks = modifiers_calcDataMasks(scene, ob, md, dataMask, required_mode, NULL, 0);
+	/* copied from mesh_calc_modifiers */
+	if (do_mod_wmcol) {
+		previewmd = modifiers_getLastPreview(scene, md, required_mode);
+		/* even if the modifier doesn't need the data, to make a preview it may */
+		if (previewmd) {
+			if (do_mod_wmcol) {
+				previewmask = CD_MASK_MDEFORMVERT;
+			}
+		}
+	}
+
+	datamasks = modifiers_calcDataMasks(scene, ob, md, dataMask, required_mode, previewmd, previewmask);
 
 	curr = datamasks;
 	for (i = 0; md; i++, md = md->next, curr = curr->next) {