On 03/01/12 21:58, Adams, Robert wrote:
...
According to [2], the maximum reported scripting collision contacts is 8.
Testing with 8 on Wright Plaza today in the Tuesday meeting seemed to greatly
reduce physics scene time compared to
previously without any apparent loss of required fidelity (50ms with 18
avatars, albeit mostly sitting down -
unfortunately I didn't record previous week's numbers but they were higher.
Nebadon tested one of his vehicles).
Looking at the code, contacts_per_collision is the number of collision points
reported by ODE for each collision -- like a prim sitting on rough terrain and
touching multiple places on the ground. Reducing the count to 8 means that no
more than 8 contact points will be reported by ODE and, if there are more, you
can't be sure you get the 'best' ones.
I suspect that most of the time there are only a few contact points so it
doesn't make sense that reducing the number from 80 to 8 would significantly
reduce the compute time. If it is the number of contact points causing the
computation overhead then ODE must be normally returning more than 8 contact
points. Is this really the case? Or is something else going on?
This is a good point. I need to go back and poke at ODE some more to see how many collisions are coming back. But from
my avatar stress testing, the reducing in physics time from reducing the collision number is very real.
--
Justin Clark-Casey (justincc)
http://justincc.org/blog
http://twitter.com/justincc
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