GL Grayscale 8-bit texture alignment

[fafok29]

I haven't found a way to specify pixel storage modes, so I can't use grayscale textures, which are not 4bytes aligned. Is there a way to do this?

[floooh]

Looks like you found an oversight in the backend code (using textures with an row-pitch that isn't a multiple of 4 on GL). I modified the texcube-sapp.c sample to use a 5x5 SG_PIXELFORMAT_R8 texture, and that looks correct in the Metal backend, but messed up in the GL backend (on macOS).

I general, odd row pitches should be allowed as input, no matter what the alignment requirements are for the backend 3D API (because those alignment requirements wildly differ, with WebGPU currently being the worst offender) - only for textures without mipmaps of though.

I'll try to look into the issue when I'm back in Berlin and have access to my Windows machine again (need to check behaviour on D3D11 first).

Until then the only workaround I can think of without modifying sokol_gfx.h is to use SG_PIXELFORMAT_R8 textures with a width that's a multiple of 4.

[floooh]

Looking into this now. D3D11 accepts textures with odd rowpitch, and WebGL has the required PixelStore API function, so it should be possible to fix (https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext/pixelStorei)

[floooh]

Ok, this should be fixed now. I'm globally setting GL_UNPACK_ALIGNMENT to 1, which should make GL behave the same as the other backends.

Be aware though the GLES2/WebGL1 generally don't support any textures that are not 2^N in size.

[fafok29]

Great, thank you.