Answer by Dan 12

There seems to be a lot of activity in the light volumes department so it would not surprise me if there is a good solution shader around the corner. For now I think the standard mesh method and glow effect or custom god ray post effect are the main staple. The glow post effect reacts to alpha channel intensity in the scene where by black blocks and white glows, so tou could ensure the alpha channel of your volume mesh is right up there. See the thread Post Process Godrays