[ODE] Collision Trimesh-Box

Oleh Derevenko oder at eleks.lviv.ua
Tue Sep 4 09:57:37 MST 2007


So, the time I'll need to "apply my hands" to ODE inevitably approaches. 
Therefore I'd like to do some preparations/consultations, since I did not 
participate in this development before.

First of all, briefly about my project I use ODE with.
I develop a realtime system which among other tasks needs to check for 
collisions among 3D objects. I do not need to calculate any physics - I get 
locations of all the objects from other sources. I only need to check if 
there is a collision among any of them or not.
The realtime nature of the system puts strict limitations on time I can 
spend in collision checking. So, I'm going to put dCollide() invocations in 
background thread and request it to abort its job if I see I can't be in 
time with calculations.
In my case, the set of geometries is not predefined, but defined by users 
(who are substances beyond the control of my application :)), and who can 
define large trimeshes which can take 100ms and more for single geometry 
pair collision checking while my limit for verification of whole space is 
much less than that. That's why I need to be able to abort dCollide() 
execution as soon as possible on request.

1) The initial problem I can see is that collision ckecking is only the 
envelope around OPCODE and/or GIMPACT libraries which are developed outside 
of ODE. Also there can be other collider systems used. Even if I add support 
for preliminary exit in major execution points there I doubt my changes 
could be merged to original sources of those libraries (at least not within 
this development community). And, more important, I'm not sure there would 
be people among initial developers of those libraries who would support this 
feature during further evolution of their libraries. On the other hand, as 
far as I noted on a quick glance (I did not do thorough investigation yet) 
the majority of execution time is spent within the interiors of those 
libraries and I definitely need to do something to gain control on that 
time. So this is the first and the most difficult obstacle.

2) Next, regardless of item 1), if I would have changes I considered to be 
worth/acceptable for merging into ODE sources who of ODE developers will 
have time to review them and do actual commit to SVN for me?

Thank you in advance.

Oleh Derevenko
-- ICQ: 36361783

----- Original Message ----- 
From: "Jon Watte (ODE)" <hplus-ode at mindcontrol.org>
To: "Oleh Derevenko" <oder at eleks.lviv.ua>
Cc: <ode at ode.org>
Sent: 14 серпня 2007 р. 20:42
Subject: Re: [ODE] Collision Trimesh-Box

> Well, feel free to supply a patch to make it better!
> As you know, optimize for the common case, make the uncommon case 
> correct...

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