Fix #32219: Inconsistent influence of Units Scale on new objects

Made it so meshes, curves, surfaces and metaballs are scaling to a grid cell size,
which makes them behave consistently now.

There're still issues to be resolved still:

- Lattice is not scaled to grid cell size yet, it uses slightly different add
  function which makes scaling a bit tricky and hacky. Would prefer to do a
  bit bigger refactor here, so it's a TODO for now.

- Cameras, speakers and other helpers are not scaling. They don't have data
  on which scale could be applied and perhaps it should be some kind of draw
  scale. Also would consider it's a TODO for now.

1 files changed, 17 insertions, 6 deletions

diff --git a/source/blender/editors/object/object_add.c b/source/blender/editors/object/object_add.c
index dc20e0d69cd..9a2915a5d55 100644
--- a/source/blender/editors/object/object_add.c
+++ b/source/blender/editors/object/object_add.c
@@ -186,7 +186,8 @@ void ED_object_base_init_transform(bContext *C, Base *base, const float loc[3],
 /* Uses context to figure out transform for primitive.
  * Returns standard diameter. */
 float ED_object_new_primitive_matrix(bContext *C, Object *obedit,
-                                     const float loc[3], const float rot[3], float primmat[][4])
+                                     const float loc[3], const float rot[3], float primmat[][4],
+                                     int apply_diameter)
 {
 	Scene *scene = CTX_data_scene(C);
 	View3D *v3d = CTX_wm_view3d(C);
@@ -209,8 +210,17 @@ float ED_object_new_primitive_matrix(bContext *C, Object *obedit,
 	invert_m3_m3(imat, mat);
 	mul_m3_v3(imat, primmat[3]);
 
-	if (v3d)
-		return ED_view3d_grid_scale(scene, v3d, NULL);
+	if (v3d) {
+		float dia = ED_view3d_grid_scale(scene, v3d, NULL);
+
+		if (apply_diameter) {
+			primmat[0][0] *= dia;
+			primmat[1][1] *= dia;
+			primmat[2][2] *= dia;
+		}
+
+		return dia;
+	}
 
 	return 1.0f;
 }
@@ -442,7 +452,7 @@ static int effector_add_exec(bContext *C, wmOperator *op)
 		rename_id(&ob->id, "CurveGuide");
 		((Curve *)ob->data)->flag |= CU_PATH | CU_3D;
 		ED_object_enter_editmode(C, 0);
-		ED_object_new_primitive_matrix(C, ob, loc, rot, mat);
+		ED_object_new_primitive_matrix(C, ob, loc, rot, mat, FALSE);
 		BLI_addtail(object_editcurve_get(ob), add_nurbs_primitive(C, ob, mat, CU_NURBS | CU_PRIM_PATH, 1));
 		if (!enter_editmode)
 			ED_object_exit_editmode(C, EM_FREEDATA);
@@ -547,6 +557,7 @@ static int object_metaball_add_exec(bContext *C, wmOperator *op)
 	unsigned int layer;
 	float loc[3], rot[3];
 	float mat[4][4];
+	float dia;
 
 	if (!ED_object_add_generic_get_opts(C, op, loc, rot, &enter_editmode, &layer, NULL))
 		return OPERATOR_CANCELLED;
@@ -558,9 +569,9 @@ static int object_metaball_add_exec(bContext *C, wmOperator *op)
 	else
 		DAG_id_tag_update(&obedit->id, OB_RECALC_DATA);
 
-	ED_object_new_primitive_matrix(C, obedit, loc, rot, mat);
+	dia = ED_object_new_primitive_matrix(C, obedit, loc, rot, mat, FALSE);
 
-	add_metaball_primitive(C, obedit, mat, RNA_enum_get(op->ptr, "type"), newob);
+	add_metaball_primitive(C, obedit, mat, dia, RNA_enum_get(op->ptr, "type"), newob);
 
 	/* userdef */
 	if (newob && !enter_editmode) {