I’m writing a lightmap optimization guide and I want to be sure I understand how VRAD works with lightmaps to light the luxels in the map. In-game, I’m using mat_filterlightmaps 0, mat_fullbright 2, and mat_luxels 1 to identify the luxel faces and the light they receive easier. It’s confusing me though. Take a look at this screenshot of Lumberyard:
It looks like the sample points are actually at the corners of the luxels, not the center. But that doesn’t explain this:
Lumberyard has an issue where the bottom step of these stairs on the Blu side has its vertical face totally fullblack. This makes me think the sample must come from the center of the luxel, since the center of each of these luxels is underneath the displacement where it would not receive any light. But if you simply cut the bottom half of the brush off, making the step a total of 8HU tall, the problem is fixed.
Here’s another issue above a doorframe:
The luxels above the doorframe are totally fullblack and the luxel is cut in half by the brush being only 8HU tall.
And here’s one more:
The top faces of these stairs should all be relatively the same brightness, but they’re not. The luxels are all over the place. I can’t make sense of it.
So does anyone know specifically how the lightmaps are used with VRAD? Where the sample points come from etc.? This shit is confusing me.