Aaron Hightower (aaron++at++qbert.dseg.ti.com)
Wed, 10 Aug 1994 15:16:14 -0500 (CDT)
If you use a pfDCS, the bounding volume of the child tree is recomputed
automatically for you. Otherwise, you'll have to keep track of it yourself.
If Performer keeps track of whether your matrix if affine or not (and it
could rather easily) it shouldn't be any faster to do the translation and
rotation in a callback. Check page 286 of the programming guide for details
on affine matrices. The Performer team will have to verify if you would
gain anything at all from using a draw callback for this, but I'll go out
on a limb and guess, no.
>Is it possible to define a projection-matrix of my own ?
If you want to define your own projection matrix, you should be able to
do so without having to explicitly create the matrix. See the man page
on pfFrustum. If you want to position the eyepoint via a matrix, use
pfChanViewMatrix.
>If so, do I have to modify GL-matrices in the DrawCallback ?
The man page for pfFrustum details the effect of the viewing Performer
pfFrustum on the GL matrices.
>What about performance in this context ?
Again, I'm guessing, but I doubt there is a speedup. You would most likely
be reimplementing some of Performer unnecessarily.
Hope this helps,
_ _
| | *-------------------------------------------* | |
__| |___ | Aaron.Hightower++at++dseg.ti.com 214.575.6759 | __| |___
\ / | Simulation & Planning Technology | \ /
\_ / | 6620 Chase Oaks Blvd M/S 8518 | \_ /
\ ( | Plano TX 75023 | \ (
\/ *-------------------------------------------* \/
This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:50:26 PDT