[ODE] Getting Triangle Index from a ray-trimesh collision?

[Geoff Carlton]

This may be able to be used in the simple ray-triangle case, but in 
general ode needs a way of associating contacts and the actual triangle 
index.  To do this, you have to extend dContactGeom and add two extra 
fields:
  int side1,side2;
These can be set in the trimesh colliders to the appropriate triangle 
index.  Furthermore, they could be extended in future to return side 
information about other geom types, for example side [0..5] for a box.  
This was discussed previously, and I have implemented it, but due to 
other changes I don't have a nice diff to send.

Geoff


Cristian Bianchi wrote:

>Hello,
>You should use the ray callback feature. Ode allows you to specify a
>callback function for each trimesh geom. take a look at the user guide:
>
>typedef int dTriRayCallback (dGeomID TriMesh, dGeomID Ray, int
>TriangleIndex, dReal u, dReal v);
>void dGeomTriMeshSetRayCallback (dGeomID g, dTriRayCallback* Callback);
>dTriRayCallback *dGeomTriMeshGetRayCallback (dGeomID g);
>        Optional Ray callback. Allows the user to determine if a ray
>collides with a triangle based on the barycentric coordinates of an
>intersection.
>
>Every time a ray - trimesh collision occurs, the specified callback is
>called and you can use the TriangleIndex for your purposes.
>
>Regards
>Cristian Bianchi
>Simulation Software Division
>DIES Group srl - Rome, Italy
>
>----- Original Message ----- 
>From: "Patrick McColgan" <patrick at torcinteractive.com>
>To: <ODE at q12.org>
>Sent: Tuesday, March 15, 2005 6:40 PM
>Subject: [ODE] Getting Triangle Index from a ray-trimesh collision?
>
>
>  
>
>>Hello
>>
>>I'm looking to collide a ray with a trimesh but on collision I want to
>>know the index of the triangle in the trimesh involved.  I've searched
>>the mailing list and looked through the documentation and from what I
>>can see there is no function to return triangle indices.
>>
>>Stepping through the collider I can see where the index is found and
>>used but currently it isn't returned, is there any external way of
>>retrieving it?  Are there any functions at all that return a triangles
>>index?
>>
>>Thanks
>>_______________________________________________
>>ODE mailing list
>>ODE at q12.org
>>http://q12.org/mailman/listinfo/ode
>>
>>    
>>
>
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>