I wrote a similar program in plain Java + Swing (and no other libraries) years ago, which I dumped on GitHub here (there are a few screenshots): <a href="https:&#x2F;&#x2F;github.com&#x2F;idolize&#x2F;ray-tracer" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;idolize&#x2F;ray-tracer</a>