On Wed, 30 Aug 2006, Chris Hanson wrote:
Zach Deedler wrote:
Chris,
I've found dxt5 compresses the most without any noticeable artifacts. I
assume it performs better compressed, but I'm not sure. myfile.ive = 117MB
loadtime=2.8
myfile-dxt5.ive = 26MB loadtime=0.4
Again, it depends on the particular imagery. Some images do not look very
good compressed, especially when animated.
What I'm interested in is this -- my constraints do not allow me to
precompress the textures with DXT compression -- they'll be coming in from a
wavelet compressed source. So, I'm wondering if compressing on the fly to
DXTn and then uploading to the card is slower or faster than using
uncompressed textures, and by how much.
My tests showed that compressing on the fly every time is slower by a factor
of 4-6, but once images are compressed they are 2-4 times faster to load.
This also requires reading the image back from the video hardware and
writing it back out to disk. (The 4-6x slowdown includes this time.) So if
your constraints are such that you do not re-use your texture images, then
texture compression might not work well for you.
--
____ __ Eric Sokolowsky (GST) NASA Goddard Space Flight Center
/ __/__/_/__ Visualization Programmer Scientific Visualization Studio
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