ARB_texture_compression rocks!

[Lev]

Well, this post is not a question.

I just figured out how cool texture compression is.

My test program has loaded 11!!!! 2048x2048 textures with all mipmap levels and 1 texture 512x512x2 bytes, at 1024x768 resolution with 32 bit frame buffer and 32 depth buffer! - and the program run on a GF1 DDR with 32 MB videoram without any big performance hit! It runs very smooth at ~200 fps (ok I have not much geometry in the scene, but anyway)

Uncompressed, it would be 246 MB!!!!!!!! of data (GL_RGBA8 format)

With compressed textures, high-resolution textures can be applied to every surface even on consumer cards like my GF1.

And its _very_ easy to use and has only 1 drawback, if you are not precompressing your textures, the loading takes quite long. But its worth it. If you haven't used it yet, give it a try!

-Lev

[IsaackRasmussen]

Lev - Yeah you are right. It absolutely rocks, especially because it's so easy to use.
I can see that you have gotten 8x compression on your textures. I found it to compress at different levels depending on the texture... is that correct? But it is allways 4,6 or 8x.

Nvidia got Photoshop plugins to precompress on their website.
Also on Nvidia's page, you'll find a really nice doc about texcomp. It also shows you how to use the new functions to get back the compressed texture so that you can save them back to file - for quick future loads.

Very nice indeed.

[Nutty]

How do you load a pre-compressed texture? i.e. tell gl thats it's compressed, without making it do the compression again.

cheers.

Nutty

[Lev]

hm, loading precompressed textures means:

1. cannot take advantage of the newest texture compression algorithm without recompressing textures.

2. cannot just open the file and edit it in a graphics editing app.

3. cannot use gluBuild2DMipmaps, so must precompress and save all mipmap levels.

4. cannot change the resolution of the texture very easily. With textures that are not precomressed you just can call gluScaleImage and scale down the base texture (mipmap level 0), which allows configuration for slower/less video memory hardware.

5. The loading is faster.

for me (1+2+3+4) >> (5), so I won't precompress textures. For other apps, the importance of these factors may vary, so precompressing may be considered.

-Lev

[andrewl]

To load a precompressed texture, use glCompressedTexImage2DARB. The <internalformat> argument specifies which texture compression algorithm was used.

[IsaackRasmussen]

Does anyone of you know if the TGA format supports RLE compressed 32bit files?

Photoshop doesn't seem to support it, only 24bit.

[Lev]

yes it does

-Lev

[IsaackRasmussen]

Know any progs that supports it then?

ImageRobot doesn't either.

[Lev]

Paint shop pro does, for example.

-Lev

[davepermen]

Originally posted by Lev:
hm, loading precompressed textures means:

1. cannot take advantage of the newest texture compression algorithm without recompressing textures.

2. cannot just open the file and edit it in a graphics editing app.

3. cannot use gluBuild2DMipmaps, so must precompress and save all mipmap levels.

4. cannot change the resolution of the texture very easily. With textures that are not precomressed you just can call gluScaleImage and scale down the base texture (mipmap level 0), which allows configuration for slower/less video memory hardware.

5. The loading is faster.

for me (1+2+3+4) >> (5), so I won't precompress textures. For other apps, the importance of these factors may vary, so precompressing may be considered.

-Lev

hm, while developping, yes, but if you finished your program, the 1 and 2 are not important, and 5 is very nice indeed.. on the other side, 3 and 4, i dont really need them, so for shipping out, i will possibly store all pix as compressed ones, other new feature: they wont steal your textures, cause most cant do anythign with them ( ok, you could load it with opengl and uncompress it and do it, but simply copieing out of the folder dont work.. )

as yet said, while developping, no, but as last optimization, yes