Two questions about textures

[Raptir]

- What are the different "Texture Formats" in the OpenGL options? RGBA8, RGB5_A1, etc... Is there one that's the "best" or what?
- I take it I'll be better off using the high resolution texture pack (http://forums.yaa.dk/viewtopic.php?f=32&t=69) than simply using the high-quality resize mode option?

Thanks.

[Rachael]

- What are the different "Texture Formats" in the OpenGL options? RGBA8, RGB5_A1, etc... Is there one that's the "best" or what?

The texture formats control the quality of textures sent to your video card. The lower the quality, the less colors you see, the worse they look, etc. This is mostly useful if you have a really really old video card and you want to save some video memory and speed things up a bit. Also useful for wads that use a ton of textures, too, especially if you opt not to use shaders.

- I take it I'll be better off using the high resolution texture pack (http://forums.yaa.dk/viewtopic.php?f=32&t=69) than simply using the high-quality resize mode option?

That's really a matter of preference. The texture pack is not Doom, it's just based on it, and the textures only bear some resemblance to the original textures that they are supposed to represent. This is for legal reasons, though, and nothing can really be done about it.

The HQ resize mode is buggy, at best, but it works. It will produce high resolution textures, however it will not improve the quality of the textures like the texture pack would. Personally, I find it unappealing because the result looks like an acrylic painting and doesn't improve the look of the textures any. If it could handle gradients better, I think I would be using it a lot more.

[Raptir]

Alright, thanks. So is the RGBA8 the highest quality? It's tough to see the difference between that and the settings closest to it. Also, is there a reason why I'd want to disable shaders...? I have to admit I don't notice much of a difference with them on or off.

[Rachael]

RGBA8 is the highest, yes.

And you'd only want to disable shaders if you have a crappy video card like mine that can't handle them too well. With my card, the game runs much faster without shaders.

[Gez]

Alright, thanks. So is the RGBA8 the highest quality? It's tough to see the difference between that and the settings closest to it.

RGBA8 means that each of the channels (Red, Green, Blue and Alpha) have 8 bits. So you have 24-bit colors with 256 levels of translucency, ranging from fully opaque to fully transparent.

RGB5_A1 means that each of the color channels have 5 bits, and the alpha channel gets only one. So you get 15-bit colors and it's either fully opaque or fully transparent.

If you play Doom, you're not going to notice a real difference because Doom uses a limited palette of 256 colors and only two levels of transparency, so RGB5_A1 can faithfully render it without loss of quality.

But if you play some mods with "truecolor" textures and/or partial transparency, RGBA8 is preferred.

The HQ resize mods are mostly for people who want higher res-looking stuff without losing the crisp contrasts from the original pixels.

[Chris]

Perhaps this should be asked in Feature Suggestions or something, but is there any way to define a texture to be loaded as a specific type? For instance if you use a texture pack that uses DDS images, they can be pre-compressed as DXT1/3/5 (the formats compress rather well for real-time use and can actually be faster when used due to the reduced memory load), so loading them as RGBA8 would be wasteful, and RGB5_A1 would reduce the quality even more (and still be a bit wasteful). However, setting all textures to load as DXT1/3/5 would reduce the quality of textures that aren't DXT-compressed.

[Graf Zahl]

No. Currently there is no such option and it's also not easy to implement because no texture goes to the low level code unprocessed. Anything is decompressed to RGB8 and then subjected to some analysis and possibly preprocessing before being sent to the hardware.