fix [#35555] Collada: export destroys mesh in some cases

add arguments to calculate normals when converting to bmesh:
  BM_mesh_bm_from_me, DM_to_bmesh

This gives some speedup to undo (which didnt need to re-calculate vertex normals), and array modifier which doesnt need to calculate face normals at all

1 files changed, 5 insertions, 1 deletions

diff --git a/source/blender/modifiers/intern/MOD_decimate.c b/source/blender/modifiers/intern/MOD_decimate.c
index b8dccd9ffbe..aacf622c185 100644
--- a/source/blender/modifiers/intern/MOD_decimate.c
+++ b/source/blender/modifiers/intern/MOD_decimate.c
@@ -97,6 +97,7 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob,
 	DecimateModifierData *dmd = (DecimateModifierData *) md;
 	DerivedMesh *dm = derivedData, *result = NULL;
 	BMesh *bm;
+	bool calc_face_normal;
 
 	float *vweights = NULL;
 
@@ -112,16 +113,19 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob,
 			if (dmd->percent == 1.0f) {
 				return dm;
 			}
+			calc_face_normal = true;
 			break;
 		case MOD_DECIM_MODE_UNSUBDIV:
 			if (dmd->iter == 0) {
 				return dm;
 			}
+			calc_face_normal = false;
 			break;
 		case MOD_DECIM_MODE_DISSOLVE:
 			if (dmd->angle == 0.0f) {
 				return dm;
 			}
+			calc_face_normal = true;
 			break;
 	}
 
@@ -159,7 +163,7 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob,
 		}
 	}
 
-	bm = DM_to_bmesh(dm);
+	bm = DM_to_bmesh(dm, calc_face_normal);
 
 	switch (dmd->mode) {
 		case MOD_DECIM_MODE_COLLAPSE: