Hi,

I'm having performance issues using multipass rendering with floating
textures. I'm rendering the scene to a texture, performing some post
process on it, then displaying the final result on screen. This works
fine with 2 pre-render passes, but once I have 3 or more passes my
performance drops drastically. If I don't use floating textures then
the perfomance is fine.

I thought this might be a memory issue with my graphics card, but I'm
using 16-bit buffers and really small textures sizes (64x64).

I even noticed this problem with the osgprerender example. I get the
following results:

osgprerender cessna.osg --hdr --width 1024 --height 1024

Draw time: 1.4
GPU time: 1.8

osgprerender cessna.osg --hdr --width 512 --height 512

Draw time: 1.4
GPU time: 0.8

osgprerender cessna.osg --hdr --width 64 --height 64

Draw time: 15.8
GPU time: 3.0

osgprerender cessna.osg --hdr --width 32 --height 32

Draw time: 15.8
GPU time: 2.5

This seems kind of counter intuitive. Does anybody have any idea what
might be going on here?

BTW, I have a GeForce 6800 GT with 256 MB

-Farshid
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