You don’t seem to be adding the imageActor to the renderer. You are calling
renderer.addActor(volume); // what is volume?
You will want to add the imageActor to the renderer, like this:
renderer.addActor(imageActor);
You don’t seem to be adding the imageActor to the renderer. You are calling
renderer.addActor(volume); // what is volume?
You will want to add the imageActor to the renderer, like this:
renderer.addActor(imageActor);