Fix T49423: Data Preview of group containing only group instances is empty.

Code was not getting correct boundbox in some cases (group only instancing other groups e.g.), now
compute our own bbox in those cases.

Based on patch by @lichtwerk, but extended the fix to include linked datablocks in some cases
(linked objects in local groups, linked objects in local scene, etc.), this was also broken in existing code.

Reviewers: mont29

Subscribers: duarteframos

Differential Revision: https://developer.blender.org/D2257

release/scripts/modules/bl_previews_utils/bl_previews_render.py

@@ -236,8 +236,8 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
         return success
 
     def objects_render_engine_guess(obs):
-        for obname in obs:
-            ob = bpy.data.objects[obname, None]
+        for obname, libpath in obs:
+            ob = bpy.data.objects[obname, libpath]
             for matslot in ob.material_slots:
                 mat = matslot.material
                 if mat and mat.use_nodes and mat.node_tree:
@@ -247,10 +247,20 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
         return 'BLENDER_RENDER'
 
     def object_bbox_merge(bbox, ob, ob_space, offset_matrix):
-        if ob.bound_box:
+        # Take group instances into account (including linked one in this case).
+        if ob.type == 'EMPTY' and ob.dupli_type == 'GROUP':
+            grp_objects = tuple((ob.name, ob.library.filepath if ob.library else None) for ob in ob.dupli_group.objects)
+            if (len(grp_objects) == 0):
+                ob_bbox = ob.bound_box
+            else:
+                coords = objects_bbox_calc(ob_space, grp_objects,
+                                           Matrix.Translation(ob.dupli_group.dupli_offset).inverted())
+                ob_bbox = ((coords[0], coords[1], coords[2]), (coords[21], coords[22], coords[23]))
+        elif ob.bound_box:
             ob_bbox = ob.bound_box
         else:
             ob_bbox = ((-ob.scale.x, -ob.scale.y, -ob.scale.z), (ob.scale.x, ob.scale.y, ob.scale.z))
+
         for v in ob_bbox:
             v = offset_matrix * Vector(v) if offset_matrix is not None else Vector(v)
             v = ob_space.matrix_world.inverted() * ob.matrix_world * v
@@ -269,8 +279,8 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
 
     def objects_bbox_calc(camera, objects, offset_matrix):
         bbox = (Vector((1e9, 1e9, 1e9)), Vector((-1e9, -1e9, -1e9)))
-        for obname in objects:
-            ob = bpy.data.objects[obname, None]
+        for obname, libpath in objects:
+            ob = bpy.data.objects[obname, libpath]
             object_bbox_merge(bbox, ob, camera, offset_matrix)
         # Our bbox has been generated in camera local space, bring it back in world one
         bbox[0][:] = camera.matrix_world * bbox[0]
@@ -333,7 +343,7 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
                 continue
             if root.type not in OBJECT_TYPES_RENDER:
                 continue
-            objects = (root.name,)
+            objects = ((root.name, None),)
 
             render_engine = objects_render_engine_guess(objects)
             render_context = render_contexts.get(render_engine, None)
@@ -344,8 +354,8 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
             scene = bpy.data.scenes[render_context.scene, None]
             bpy.context.screen.scene = scene
 
-            for obname in objects:
-                ob = bpy.data.objects[obname, None]
+            for obname, libpath in objects:
+                ob = bpy.data.objects[obname, libpath]
                 if obname not in scene.objects:
                     scene.objects.link(ob)
                 ob.hide_render = False
@@ -363,8 +373,8 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
             #         OverflowError: Python int too large to convert to C long
             #    ... :(
             scene = bpy.data.scenes[render_context.scene, None]
-            for obname in objects:
-                ob = bpy.data.objects[obname, None]
+            for obname, libpath in objects:
+                ob = bpy.data.objects[obname, libpath]
                 scene.objects.unlink(ob)
                 ob.hide_render = True
 
@@ -377,7 +387,8 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
         for grp in ids_nolib(bpy.data.groups):
             if grp.name in groups_ignored:
                 continue
-            objects = tuple(ob.name for ob in grp.objects)
+            # Here too, we do want to keep linked objects members of local group...
+            objects = tuple((ob.name, ob.library.filepath if ob.library else None) for ob in grp.objects)
 
             render_engine = objects_render_engine_guess(objects)
             render_context = render_contexts.get(render_engine, None)
@@ -415,7 +426,7 @@ def do_previews(do_objects, do_groups, do_scenes, do_data_intern):
             objects = None
             if not has_camera:
                 # We had to add a temp camera, now we need to place it to see interesting objects!
-                objects = tuple(ob.name for ob in scene.objects
+                objects = tuple((ob.name, ob.library.filepath if ob.library else None) for ob in scene.objects
                                         if (not ob.hide_render) and (ob.type in OBJECT_TYPES_RENDER))
 
             preview_render_do(render_context, 'scenes', scene.name, objects)