Try to use collisions from basic actor model if an animated one has no collisions (feature #4682)

CHANGELOG.md

@@ -175,6 +175,7 @@
     Feature #4632: AI priority: utilize vanilla AI GMSTs for priority rating
     Feature #4636: Use sTo GMST in spellmaking menu
     Feature #4642: Batching potion creation
+    Feature #4682: Use the collision box from basic creature mesh if the X one have no collisions
     Task #2490: Don't open command prompt window on Release-mode builds automatically
     Task #4545: Enable is_pod string test
     Task #4605: Optimize skinning

apps/openmw/mwphysics/physicssystem.cpp

@@ -1337,6 +1337,16 @@ namespace MWPhysics
         if (!shape)
             return;
 
+        // Try to get shape from basic model as fallback for creatures
+        if (!ptr.getClass().isNpc() && shape->mCollisionBoxHalfExtents.length2() == 0)
+        {
+            const std::string fallbackModel = ptr.getClass().getModel(ptr);
+            if (fallbackModel != mesh)
+            {
+                shape = mShapeManager->getShape(fallbackModel);
+            }
+        }
+
         Actor* actor = new Actor(ptr, shape, mCollisionWorld);
         mActors.insert(std::make_pair(ptr, actor));
     }