Eamae Mirkin

Good question. The short answer is that it's not actually volumetric. The colored point "lights" are just billboarded textures, with additive blending. Then the whole scene is wrapped in a giant sphere, and lit with point lights in the same positions as the billboards. At the time I was painfully new to open gl, so I chose to write my own lighting engine, rather than figure out how to use gl lighting. Basically, every vertex calculates it's color based on the distance from each light source, additively. This part happens on the processor though, not the graphics card, so it's not as fast.

If you're interested real (well, virtually real) volumetric lighting, you should check out sunflow render engine:
hipstersinc.com/p5sunflow/.

Excellent work, sir! I really enjoyed your other videos as well. Thanks for the credit, and keep it up!