drewcassidy/nvidia-texture-tools
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Edited wiki page through web user interface.

Browse Source
This commit is contained in:
castano 2007-10-30 07:09:21 +00:00
parent 7c5e78c1d1
commit c491dcba73
1 changed files with 8 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
wiki/HighQualityDXTCompression.wiki
View File

@ -22,4 +22,11 @@ One alternative I want to try is using two DXT1 textures with the same mapping a
tex t0
tex t1
lerp r0, t0.a, t0, t1
}}}
}}}
This approach is interesting, but according to Tom, it doesn't work that well in practice.
Instead he suggests doing something similar to Humus' compression, but using an uncompressed RGB-565 texture, and a separate luminance texture. The original texture is downsampled to 1/4th its size, and the luminance texture encodes the luminance difference between the original and the downsampled texture. The luminance deltas usually have a small range, so you could use a per texture scale factor to scale the deltas to the representable range, and obtain higher precision. Tom [http://home.comcast.net/~tom_forsyth/blog.wiki.html#%5B%5BTexture%20formats%20for%20faster%20compression%5D%5D explains it with more details on his blog].
The advantage of this method is that compression is very fast, the downsampled texture is only quantized, and the luminance texture is 1D, so it has a small search space. He has not done any PSNR analysis, thought.