[ODE] Trimesh-trimesh and dGeomTriMeshDataSet

[Patrick Enoch]

Hello,

mesh-mesh collision is a mess. maybe you can start fixing the box- 
mesh collider... I am currently trying to figure out how it
works.

Patrick


On 21. Jun 2005, at 14:09 Uhr, Peter Kyme wrote:


> Hi All,
>
> I'm having some issues with trimesh-trimesh collisions and I'd  
> appreciate it if someone could point me in the right direction.
>
> The problem manifests itself as reversed contact normals being  
> returned from dCollide for half of the collisions. I have a  
> collection of simple tests, and half of these will fail  
> (interpenetration of geoms). If I manually reverse the contact  
> normals, the other half will fail.
>
> For example, the following system works fine:
>
>   +--+
>   |  |
>   +--+
> +------+
> |      |
> |      |
> +------+
>
> Here the larger box is static, and the smaller box collides with it  
> as expected. However if the situation is reversed:
>
> +------+
> |      |
> |      |
> +------+
>   +--+
>   |  |
>   +--+
>
> The larger box completely penetrates the smaller (static) box,  
> unless I reverse contact normals.
>
> I am of the impression this could be related to incorrectly calling  
> the
> dGeomTriMeshDataSet( TriMeshData, TRIMESH_LAST_TRANSFORMATION ...
> function.
>
> Currently my main simulation loop looks like this:
>
> loop {
>    space->collide()
>    for all bodies{ setTrimeshLastTransform() }
>    dWorldStep()
>    space->cleanupCollisions()
> }
>
> and setTrimeshLastTransform() looks like:
>
> const dReal *rot = dBodyGetRotation(m_body);
> const dReal *pos = dBodyGetPosition(m_body);
> const double trans[16] = {rot[0], rot[1], rot[2], pos[0],
>                           rot[4], rot[5], rot[6], pos[1],
>                           rot[8], rot[9], rot[10], pos[2],
>                           0, 0, 0, 1.0 };
> dGeomTriMeshDataSet( meshId, TRIMESH_LAST_TRANSFORMATION, (void *)  
> trans );
>
> I'm using a stepsize of 0.005, maximum contacts of 80, and I'm  
> letting ODE calculate the trimesh normals.
>
> Does anyone have any ideas what might be going wrong?
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>