He didn’t. He just raycasts for each pixel and takes the brick color of the point where the ray hits. You can determine if a point is in shadow or not by raycasting from the point of impact of the first ray towards the light source / light direction.
I ported Dr. Kleiner’s Lab (from Half-Life 2) into Roblox
You can check this out for yourself here:
I’ve been doing these ports as a sort of proof of concept, to see what Roblox is aesthetically capable of now. Every mesh in this video was manually ported, and the level was generated using my VMF importer. The plotter effect is done using a Beam, and the glowing orange tubes use a combination of Neon, Glass, and ParticleEmitters to provide its effect.
The biggest hurdle I had to get over was manually porting every single mesh. My importer tells me what meshes I need to import and does the positioning for me, but its up to me to extract each mesh and convert it over to FBX. It required a metric f##k-ton of individual meshes to be ported.