Blender Robotartist: only create one collection and place geometry inside

Issue #759

Author: robin-gdwl

src/compas_blender/artists/robotmodelartist.py

@@ -29,6 +29,8 @@ def transform(self, native_mesh, transformation):
 
     def draw_geometry(self, geometry, name=None, color=None):
         # Imported colors take priority over a the parameter color
+        # TODO: cleanup confusion between layers and collections
+
         if 'mesh_color.diffuse' in geometry.attributes:
             color = geometry.attributes['mesh_color.diffuse']
 
@@ -40,11 +42,22 @@ def draw_geometry(self, geometry, name=None, color=None):
             color = [1., 1., 1.]
 
         if self.layer:
-            collection = bpy.data.collections.new(self.layer)
-            bpy.context.scene.collection.children.link(collection)
+            
+            current_collections = bpy.data.collections.items()
+            #print(bpy.data.collections)
+            #print(bpy.data.collections.keys())
+
+            if self.layer not in bpy.data.collections.keys():
+                collection = bpy.data.collections.new(self.layer)  # create new collection if none exists
+                bpy.context.scene.collection.children.link(collection)  # link the new collection to the base collection
+            else: 
+                collection = bpy.data.collections.get(self.layer)
+               # print(collection)
+            
 
         v, f = geometry.to_vertices_and_faces()
-        return compas_blender.draw_mesh(vertices=v, faces=f, name=name, color=color, centroid=False, layer=self.layer)
+        # Draw the mesh in blender in the specified collection
+        return compas_blender.draw_mesh(vertices=v, faces=f, name=name, color=color, centroid=False, collection=self.layer)
 
     def redraw(self, timeout=None):
         bpy.ops.wm.redraw_timer(type='DRAW_WIN_SWAP', iterations=1)

src/compas_blender/utilities/drawing.py

@@ -46,10 +46,11 @@ def _link_objects(objects, collection=None, layer=None):
     # if not layer:
     #     layer = bpy.context.view_layer
     # layer_collection = layer.active_layer_collection.collection
+    
     for o in objects:
         for c in o.users_collection:
             c.objects.unlink(o)
-        collection.objects.link(o)
+        collection.objects.link(o)  # TODO: why does this not work
         # layer_collection.objects.link(o)