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Weird behavior of transparent surfaces

dsvensson opened this issue · comments

commented

I'm experimenting with adding a Quake 1 BSP loader to RTXDI to use as a light preview app during map creation. The goal is for it to approximate the result of the existing lightmap generator but in realtime because it's not using the GPU, but does a good job.

I'm having some trouble getting transparent surfaces to look good. In the image here you can see some roof windows that look glitched, the glitchiness moves around like smearing the edges in lack of a better word, while their reflections are without artifacts however I pan around the view. It seems to be isolated to transparencies towards the "outside world". If there's geometry on both sides, there are no issues as seen on the lower left glassy material.

image

Ideally I would like to create transparent surfaces without reflection as Quake 1 doesn't have real time rendering, and the existing lightmap generator ignores that and only uses ray tracing for light bounces, so if it's possible to have a fully diffuse semi-transparent material that only lets light through and receives bounced rays that would be a nice workaround.

Sorry for adding more topics here, but don't want to spam the issue tracker.

  • Q1 has two ways of tuning lights. You can have a wait that scales the fade distance of the light, and you can control falloff via delay (0: linear, 1: 1/x, 2: 1/x^2, 3 and 4 are less relevant, 5: alternate 1/x^2 without burning out near source), would this type of falloff change be fairly easy for me to add or is it just fundamentally incompatible with this type of ray tracing and requiring major changes?
  • Can emissive surfaces be tuned to produce bouncing light without burning the texture at higher levels?
  • I'm currently making transparent materials emissive to have the texture showing similar to how it would in Q1, but this ofc breaks shadows of such surfaces, like the water under a bridge wouldn't get shadows if it's emissive. Any other possibility to deal with that?

For reference, this is what I have working, different map than screenshot, but can also observe the weird reflections there even if view doesn't stay around to study that issue specifically, https://youtu.be/Zm7ADUgg5Yo

commented

nvm, went with UE5 instead.