Smarter handling of BMesh. Sharp edges are ignored only if auto-smooth

is on, just like Blender does.

korman/exporter/etlight.py

@@ -201,19 +201,13 @@ class LightBaker:
         # (If the object has an edge split modifier, well, screw you!)
         for bo in blender_objects:
             mesh = bo.data
-            bm = bmesh.new()
-            bm.from_mesh(mesh)
-
-            light_vcol = bm.loops.layers.color.get(self.vcol_layer_name)
-
-            # If no vertex color is found, then baking either failed (error raised by oven)
-            # or is turned off. Either way, bail out.
-            if light_vcol is None:
-                bm.free()
-                del bm
+            if self.vcol_layer_name not in mesh.vertex_colors:
+                # No vertex color. Baking either failed or is turned off.
                 continue
 
+            with bmesh_from_object(bo) as bm:
                 bm.faces.ensure_lookup_table()
+                light_vcol = bm.loops.layers.color.get(self.vcol_layer_name)
 
                 for face in bm.faces:
                     for loop in face.loops:
@@ -227,9 +221,10 @@ class LightBaker:
                             if len(edge.link_faces) != 2:
                                 # Either a border edge, or an abomination.
                                 continue
-                        if not edge.smooth or (mesh.use_auto_smooth and
-                                               edge.calc_face_angle() > mesh.auto_smooth_angle):
-                            # Sharp edge. Don't care.
+                            if mesh.use_auto_smooth and (not edge.smooth
+                                    or edge.calc_face_angle() > mesh.auto_smooth_angle):
+                                # Normals are split for edges marked as sharp by the user, and edges
+                                # whose angle is above the theshold. Auto smooth must be on in both cases.
                                 continue
                             if face in edge.link_faces:
                                 # Alright, this edge is connected to our loop AND our face.
@@ -247,8 +242,6 @@ class LightBaker:
                         loop[light_vcol] = max_color
 
                 bm.to_mesh(mesh)
-            bm.free()
-            del bm
 
     def _generate_lightgroup(self, bo, user_lg=None):
         """Makes a new light group for the baking process that excludes all Plasma RT lamps"""