Doom 1 Parallax Mapping

Re: Doom 1 Parallax Mapping

Postby Darkcrafter » Fri Sep 28, 2018 3:40 am

I found out the technique is called Parallax Occlusion Mapping with Silhouettes.

https://chetanjags.wordpress.com/2013/0 ... lhouettes/

http://developer.amd.com/wordpress/medi ... D07%29.pdf
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Re: Doom 1 Parallax Mapping

Postby Chris » Fri Sep 28, 2018 8:29 am

That will still have issues with polygon edges. It's simply an unescapable fact that Parallax Mapping works by taking a to-be-rendered flat triangle surface pixel in screenspace, and adjusts the texel lookup based on camera angle to make it look like it has depth. When the view ray should cross to a differently-textured or -oriented surface, the lookup adjustment has no way to compensate so you'll get a visible seam, and more extreme parallax adjustments will show more significant seams. This is to say nothing of the pixel depth value, which creates another set of issues (either you change the depth value to its proper value and pre-shader depth-test optimizations are disabled, or you don't and the depth buffer still sees it as a flat surface).

Parallax mapping is okay enough for subtle adjustments, but if you want to really adjust the apparent depth of the geometry, you need to change the geometry. Geometry shaders were needed to properly implement displacement for a reason.
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Re: Doom 1 Parallax Mapping

Postby Darkcrafter » Fri Sep 28, 2018 5:11 pm

Yeah you're 100% correct here. I wanted to ask if there is anyway to overcome this problem? Maybe to use some linedef or point information from a map and then "blend" this seam out with a crossfade?
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Re: Doom 1 Parallax Mapping

Postby Glaice » Mon Oct 15, 2018 7:50 pm

These are great! I look forward to seeing Doom 2 added to the mix as well as fixing the step texture and inter-episode problems.
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Re: Doom 1 Parallax Mapping

Postby Sinael » Sun Oct 21, 2018 2:03 pm

Is it possible to make separate filtering settings for base textures and parallax? Because for the base textures nearest looks the best, but it makes parallax look "stepped", while trilinear makes Parallax look neat, but the base texture looks smudged.
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Re: Doom 1 Parallax Mapping

Postby Darkcrafter » Mon Oct 22, 2018 7:44 am

The developer already said no.
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