Robert Osfield wrote:
Hi Zach,
Adjusting LOD ranges etc w.r.t frame time left in the current frame is
not possible due to the architecture of both the OSG and hardware.
The best you can do is monitor the CPU and GPU frame time for the
previous frame and then adjust the LOD scaling etc for the new frame.
I do this. My LODs work in pixel-screen space rather than actual distance. This seems
to work well. You generally want the metric to respond quickly to reduce the LOD, but
slowly to increase it. Quickly to reduce means you can correct conditions that would lead
to frame break. However, you need some sort of hysteresis on the detail increase side, or
your LOD will sit there and "bounce" back and forth trying to achieve a steady state it
can never attain.
In practice, my auto-LOD adjustment usually spends a lot of time bouncing. I think it
may have something to do with an error in my available-frame-time metric measurement, but
I'm not sure.
--
Chris 'Xenon' Hanson | Xenon @ 3D Nature | http://www.3DNature.com/
3D Earth: http://3d-earth.net/
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