[ODE] Slow performence in a given scene - optimizable, or "just how it is"?

[Geoff Carlton]

Just on the face of it, 246 callbacks for 9 bodies seems alot.  Either 
its picking up static-static collisions, or else you've got almost 30 
geom primitives knocking around each active body.  If its the latter 
case, I'd think about condensing it into a static trimesh, or exploiting 
game knowledge to get a better partioning scheme than one of the 
standard ones.

Geoff

Megan Fox wrote:

>Hrm... surprising results - I'd always though the total number of
>calls was larger than the number that actually go through.
>
>Profiling says that, yes, in the "bad" collision case, the total
>number of calls to my collision callback more than double.  However,
>that's still only, in this case, 246 calls, as compared to 145 in the
>"better" case.  These numbers seem a lot smaller than what I thought
>it would take to bring the system down.
>
>
>Does this seem right?  Is 246 collision callback calls, with a
>stepsize of 0.016 and 5 quickstep iters, in a world with very, very
>few actual dynamics objects (9 physical bodies total) enough to bring
>the system down like this?  Or am I seeing a problem elsewhere?
>
>(this is on an Athlon 64 2800+ - and the bad case is enough to bring
>me down to unplayably jumpy FPS)
>
>On 11/3/05, Jon Watte (ODE) <hplus-ode at mindcontrol.org> wrote:
>  
>
>>My first instinct would be to bake the collision of all static things
>>into a single static mesh (or a few, block-sized, static meshes).
>>
>>Another thing you can do is to add profiling code to count how many
>>near-callbacks you get, and store information about what attempts to
>>collide with what, and plot that. That should show you some spikes.
>>
>>Characters and other complex systems should probably be in their own
>>spaces (spaces can be hierarchical), so that they can be quickly culled
>>when not colliding with other entities.
>>
>>Last, I would absolutely use a profiler to figure out where the most of
>>the time is being spent. That would also guide me into making whatever
>>optimizations necessary.
>>
>>Cheers,
>>
>>                       / h+
>>
>>
>>Megan Fox wrote:
>>    
>>
>>>Alright, I'm coming up against a performence problem in a semi-dense
>>>scene.  Semi-dense because, while there are a lot of objects in the
>>>world, it really isn't all that "dense"... it's just a desert with
>>>rocks and a single building.  I'm trying to determine if this is
>>>expected/normal, or if I can bail myself out in some fashion.
>>>      
>>>
>>    
>>
>
>
>--
>-Megan Fox
>Lead Developer, Elium Project
>http://www.elium.tk
>
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