Ram Munjuluri (munjulur++at++ivex3d.com)
Thu, 26 Mar 1998 13:15:48 -0500
Performers:
After working with cliptexures for a week or so, I have a few
questions I can't seem to find a good answer for:
1) I'd really like to have some control over how the detail in
the mipmaps I see. It seems the biasS and biasT controls in
clipfly will degrade the mipmap levels, but they won't sharpen
it!
[Ram Munjuluri]
Hi,
Its been a long time since, I worked on this stuff, but, I hope I still remember the neat clipTex mechanism. :):)
you could vary the virtual LOD offset to bring in high-detailed clip tiles. Shifting the Virtual LOD offset will cause a slider to bring in set of mip-levels of interest. Also, U could vary this value using the height above terrain it should be a pretty good mipmapping between levels.
2) The cliptexture is always centered on my terrain directly below
me. Unfortunately, my flight sim doesn't fly looking down
(for long!) -- it looks pretty much ahead. So I see about
half of the highest detail mipmap when I'd really like to see
more. This would, I'd guess, require the centering algorithm
to take direction into account. Since the texture loading already
does this, is there any alternate centering function that can
shift the clipcenter "in front" of me? Or would this be an
exercise left to the reader ;-)
[Ram Munjuluri]
Its pretty much an exercise, but a simple one. you could add a APP callback that grabs eye-point and shifts the clipcenter accordingly, where ever you want to place it.
3) Currently, I see an abrupt change in mipmap levels on my clipmapped
terrain. Playing with all the clipfly controls, I can lessen
this distinction only by causing blurring. What I'd really like
is to "push" my highest detail mipmap border further away from the
eyepoint to make the change less apparent. How can I do this?
[Ram Munjuluri]
The clip-centering and Virtual LOD offset should take car of this. of course, the clip centering will play a major role in minimizing this effect.
4) Lastly, are there any docs detailing the relationship between
clipsize, tilesize, icache size, LODbias, and min/maxLOD (did I
forget any parameters?) and the sharpness of the clipmap?
I can accept the "default" settings I use for performance reasons,
but I sure would like to know that I can control the clipmapping
for better image quality *if* I have the time to do it.
[Ram Munjuluri]
There should a good *.doc on clipmaps in /usr/share/Performer/doc/clipmap
I hope it's still there.
[Ram Munjuluri]
Hope this helped.....
-Ram
Rambabu Munjuluri
ram++at++ivex3d.com
Thanks for any insight!
jan
--
Jan Anthony Barglowski jan++at++chinalake.navy.mil
Real-time Computer Graphics http://www1.ridgecrest.ca.us/~jan
Naval Air Warfare Center, China Lake (760) 927-1057
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