fix(actor2d): ensure that the actor2D instances are re-sorted each frame

This ensures that they are rendered in the correct order for every frame even if their layer number
changes between frames.

Author: sankhesh

Diff for: Sources/Rendering/OpenGL/Renderer/index.js

@@ -24,6 +24,15 @@ function vtkOpenGLRenderer(publicAPI, model) {
       publicAPI.updateLights();
       publicAPI.prepareNodes();
       publicAPI.addMissingNode(model.renderable.getActiveCamera());
+      // Force all actor2D instances to be sorted and re-pushed as scenegraph nodes.
+      // This ensures that they are rendered in the correct order.
+      const actors2D = model.renderable.getActors2D();
+      actors2D.forEach((ac) => {
+        const vn = publicAPI.getViewNodeFor(ac);
+        if (vn !== undefined) {
+          publicAPI.removeNode(vn);
+        }
+      });
       publicAPI.addMissingNodes(model.renderable.getViewPropsWithNestedProps());
       publicAPI.removeUnusedNodes();
     }