#5885: fix loss of attached entity offset after Reload Defs

To render the entity offset, we are using the localToParent matrix
exposed by the ITransformNode interface. However this matrix was only
being set once, when the attachments were constructed, which isn't
sufficiently "sticky" -- the localToParent matrix can easily be
recalculated by code in the attached entity itself.

We now set the localToParent matrix immediately before rendering each
attached entity, ensuring it is always up to date.

radiantcore/entity/EntityNode.cpp

@@ -137,7 +137,7 @@ void EntityNode::createAttachedEntities()
             // Construct and store the attached entity
             auto attachedEnt = GlobalEntityModule().createEntity(cls);
             assert(attachedEnt);
-            _attachedEnts.push_back(attachedEnt);
+            _attachedEnts.push_back({attachedEnt, a.offset});
 
             // Set ourselves as the parent of the attached entity (for
             // localToParent transforms)
@@ -156,8 +156,8 @@ void EntityNode::transformChanged()
 
     // Broadcast transformChanged to all attached entities so they can update
     // their position
-    for (auto attached: _attachedEnts)
-        attached->transformChanged();
+    for (auto [node, offset]: _attachedEnts)
+        node->transformChanged();
 }
 
 void EntityNode::onEntityClassChanged()
@@ -395,7 +395,7 @@ void EntityNode::setRenderSystem(const RenderSystemPtr& renderSystem)
 	_colourKey.setRenderSystem(renderSystem);
 
     // Make sure any attached entities have a render system too
-    for (IEntityNodePtr node: _attachedEnts)
+    for (auto [node, offset]: _attachedEnts)
         node->setRenderSystem(renderSystem);
 }
 

radiantcore/entity/EntityNode.h

@@ -87,7 +87,8 @@ class EntityNode :
     // sure that everything will play nicely with entities as children of other
     // entities, and (2) storing entity node pointers instead of generic node
     // pointers avoids some extra dynamic_casting.
-    using AttachedEntities = std::list<IEntityNodePtr>;
+    using AttachedEntity = std::pair<IEntityNodePtr, Vector3 /* offset */>;
+    using AttachedEntities = std::list<AttachedEntity>;
     AttachedEntities _attachedEnts;
 
   protected:
@@ -198,8 +199,11 @@ class EntityNode :
     // Render all attached entities
     template <typename RenderFunc> void renderAttachments(RenderFunc func) const
     {
-        for (const IEntityNodePtr& ent: _attachedEnts)
+        for (auto [entityNode, offset]: _attachedEnts)
         {
+            // Before rendering the attached entity, ensure its offset is correct
+            entityNode->setLocalToParent(Matrix4::getTranslation(offset));
+
             // Attached entities might themselves have child nodes (e.g. func_static
             // which has its model as a child node), so we must traverse() the
             // attached entities, not just render them alone
@@ -215,9 +219,8 @@ class EntityNode :
                     return true;
                 }
             };
-
             ChildRenderer cr(func);
-            ent->traverse(cr);
+            entityNode->traverse(cr);
         }
     }