[ODE] Objects getting stuck with tri-mesh

[Frederic Marmond]

I come late into this thread, but an idea:
perhapse could you do this:
- get the speed vector of your body(pos at this frame - pos at last frame)
- for each colliding point, check it with the normal vector. If the 
angle between the 2 vectors is less than, let's say 110°, take the 
collision into account, otherwise discard it.

it is not very clean, and will 'just make it less likely to happen'. It 
could also introduce some side-effect...

Fred

Flavien Brebion wrote:

>A smaller timestep won't fix it, it will just make it
>less likely to happen. It will also increase the CPU
>work.
>
>Extending the box depth: not possible in my case,
>the objects would look unrealistic.
>
>The dHeightField would fix it, but only for the
>terrain. The problem would still be there for other
>objects on which you can collide (mainly a road, in
>my case).
>
>F. Brebion
>
>
>-----Original Message-----
>From: ode-admin@q12.org [mailto:ode-admin@q12.org]On Behalf Of gl
>Sent: Wednesday, September 03, 2003 5:03 AM
>To: Open Dynamics Engine
>Subject: Re: [ODE] Objects getting stuck with tri-mesh
>
>
>
>Well, for one you can use a smaller timestep until you get something
>workable (smaller timestep = less penetration).  Can you not extend the box
>depth also?
>
>For the ground, another option is to use my dHeightfield contribution.  It
>only supports spheres currently, but it's written so each triangle acts like
>the planes do - ie. you can penetrate very deep, and it will still kick you
>out.
>
>I've been trying to talk someone into adding more colliders, but so far no
>luck : ).  I'll need them eventually myself, but I'm busy with other things
>right now...
>--
>gl
>
>----- Original Message -----
>From: "Flavien Brebion" <f.brebion@vrcontext.com>
>To: "Open Dynamics Engine" <ode@q12.org>
>Sent: Tuesday, September 02, 2003 2:38 PM
>Subject: [ODE] Objects getting stuck with tri-mesh
>
>
>  
>
>>I've finally found WHY i get some objects
>>stuck into my scene.
>>
>>It's actually very easy to understand. Check this
>>figure:
>>
>>http://www.fl-tw.com/LightSpeed/stuck.jpg
>>
>>If the object falls "quickly" on a pretty thin
>>box (or any actual thin solid, represented as a
>>tri-mesh), there will be reports of contact
>>points both on the upper and under sides of the
>>box -> contact forces cancel each other (or
>>almost) and the object gets stuck inside the
>>box.
>>
>>Now the question: what's a robust way to fix it?
>>
>>F. Brebion
>>
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>>
>>
>>    
>>
>
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