From: Volz, Bill (WRVO) (WRVO++at++chevron.com)
Date: 03/02/2000 13:02:13
I have luminance textures and I want to map this to an RGBA color table. Sgi
has an extension to apply a color table for textures, but I don't want to
use that - the application may need to run on non-SGI hardware. I can always
do my own lookup just prior to the downloading of the textures but there are
some difficulties with this (texture download size grows from 1 to 4
bytes/texel and hence slower performance, different lookups for different
textures, etc).
I tried to use glPixelMap/glPixelTransfer but I either didn't have things
set up right or it didn't work as I expected it to. I set the textures to
have internal format of LUMINANCE and COLOR_INDEX with the same result. I
also tried to use a post_color_matrix_color_table, but that didn't work
either - it acted like Intensity.
Does anyone have any suggestions on how to best handle this that would work
on most platforms? Ideally, I would think that glPixelMap with the texture
have an internal format of COLOR_INDEX would provide the best in download
speed, minimize texture memory utilization. Note that the color tables can
be changes by the use so they need to see the changes, hopefully without
redraw the entire picture again.
Thanks,
William R Volz - Senior Research Geophysicist
Chevron Petroleum Technology
Voice: 281-596-2059 Fax: 281-596-3009
This archive was generated by hypermail 2b29 : Thu Mar 02 2000 - 13:02:21 PST