Working on a minor derivative for Voxel Doom

[Ultimate Freedoomer]

As you guys may know, Cheello recently released the newest version of his Voxel/Parallax Doom mod. Would it be possible to modify the texture scripting so that the parallax effect works in the GLES renderer as well as the Vulkan/OpenGL renderers?

[ramon.dexter]

The parallax effect is done by shaders. Since shaders basically dont work in opengl-es, there is really nothing that could be done about it.

[Ultimate Freedoomer]

What version of GLES does GZDoom use?

[Redneckerz]

What version of GLES does GZDoom use?

GLES 2.0.

[Ultimate Freedoomer]

Alright. Hopefully it’ll get updated to 3.2 eventually. That version apparently does support shaders, given that the Delta Touch port uses it & it supports parallax textures there.

[ramon.dexter]

But delta touch doesnt support user shaders...

[Ultimate Freedoomer]

The most recent version does, apparently. Someone mentioned that enabling them is part of GLES compatibility with parallax textures for that port

[Redneckerz]

Alright. Hopefully it’ll get updated to 3.2 eventually. That version apparently does support shaders, given that the Delta Touch port uses it & it supports parallax textures there.

That's not the point of the GLES renderer. Its purpose is to render GZDoom the same as OpenGL, but with simplified shaders suitable for older GPU's.

[Ultimate Freedoomer]

A lot of it is that despite how new my GPU is, it basically becomes a potato unless I use GLES. That’s why I’m hoping for a future update to use the current version of GLES: so I can get normal OpenGL shader versatility with the speed of GLES.

[phantombeta]

GLES 2.0 supports shaders just fine, and GZDoom uses GLES 3.3 when it can. GZDoom simply ignores user shaders for performance- gl_customshader is always set to false with the GLES renderer.
The point of the GLES backend is to improve performance by splitting shaders into smaller ones (mobile GPUs and older, weaker GPUs hate "ubershaders") and disabling a significant amount of rendering features to further improve performance.

GLES in Delta Touch supports user shaders and most (all?) of GZDoom's features because GLES is what mobile GPUs use, whereas GLES in GZDoom exists solely for computers too weak to run the OpenGL or Vulkan backends at full performance.

[ramon.dexter]

GLES in Delta Touch supports user shaders and most (all?) of GZDoom's features because GLES is what mobile GPUs use, whereas GLES in GZDoom exists solely for computers too weak to run the OpenGL or Vulkan backends at full performance.

That's good to hear. Bexause everytime I wanted to use shaders in Delta Touch, it always returned an error and crashed. So there must be some error in the shaders I use or Delat Touch has some problems with the shaders I use. But these shaders work in gzdoom on windows/linux, so there must bo something with use of these shaders on Delta Touch.

[phantombeta]

That's good to hear. Bexause everytime I wanted to use shaders in Delta Touch, it always returned an error and crashed. So there must be some error in the shaders I use or Delat Touch has some problems with the shaders I use. But these shaders work in gzdoom on windows/linux, so there must bo something with use of these shaders on Delta Touch.

Different GLSL versions. GLES 3.x has features GLES 2.x doesn't. Desktop GL also has features that GLES, whether 2.x or 3.x, doesn't have either.

Nvidia and AMD also have implicitly-enabled vendor-specific extensions that add features to GLSL, which can then cause shader compilation errors in mobile GPUs because those don't have said features.
That's somewhat easier to deal with, though. Just run GZDoom with Vulkan, because then GZDoom is the one compiling the GLSL, and the compiler it uses doesn't do those things.
I'd actually generally recommend testing shaders with Vulkan in general, because there's other things, like Nvidia, AMD and Intel initializing uninitialized variables to 0, which hides bugs.