[ODE] Ray queries with GIMPACT.

[Michael Anderson]

Okay, changing the following GIMPACT code in gim_geometry.h fixes the
problem for me:

// BUGFIX: modified if (_dotdir<PLANEDIREPSILON) to if
(-_dotdir<PLANEDIREPSILON)
#define RAY_PLANE_COLLISION(plane,vDir,vPoint,pout,tparam,does_intersect)\
{\
    GREAL _dis,_dotdir;    \
    _dotdir = VEC_DOT(plane,vDir);\
    if(-_dotdir<PLANEDIREPSILON)\
    {\
        does_intersect = 0;\
    }\
    else\
    {\
        _dis = DISTANCE_PLANE_POINT(plane,vPoint);    \
        tparam = -_dis/_dotdir;\
        VEC_SCALE(pout,tparam,vDir);\
        VEC_SUM(pout,vPoint,pout);    \
        does_intersect = 1;\
    }\
}\


On 4/24/07, Michael Anderson <christiancoder at gmail.com> wrote:
>
> Hmmm, looks like it's a vertex winding issue. If I flip the vertex winding
> ray - mesh tests work, but everything else fails...
>
> On 4/24/07, Michael Anderson <christiancoder at gmail.com> wrote:
> >
> > Lately we have been experiencing capsule - mesh jitter with OPCODE.
> > After reading that GIMPACT seems to solve these collision problems I made
> > the switch. After adding dInitODE and dCloseODE to our application I was up
> > and running. GIMPACT appears to have solved the jitter problem, but I have
> > lost ray - mesh intersections. Our ray cast method follows, it basically
> > takes a global ray (that does not belong to any collision space) and calls
> > dCollide passing in our collision space as the second geom. Does GIMPACT
> > support ray - mesh (in my experience this is the easiest of all intersection
> > tests)?  If so what am I missing?
> >
> >
> > //=============================================================================
> >
> > bool castRay( RayCastResult& result, const VectorF& start, const
> > VectorF& end, const U32 types )
> > {
> >    // Calc direction and length of ray.
> >    VectorF dir = end - start;
> >    F32 const len = dir.len();
> >    dir *= (1.0f / len);
> >
> >    // Create ray.
> >    dGeomRaySetLength( gRayId, len );
> >    dGeomRaySet( gRayId, start.x, start.y, start.z, dir.x , dir.y, dir.z);
> >
> >    // Set collide bits for ray.
> >    dGeomSetCollideBits( gRayId, types );
> >
> >    // Collide ray with world.
> >    dContactGeom contacts[64];
> >    const int c = dCollide( gRayId, (dGeomID)gSpace, 64, contacts,
> > sizeof( dContactGeom ) );
> >
> >    // Did ray intersect world?
> >    if (!c)
> >    {
> >       return false;
> >    }
> >
> >    // Find the closest intersection.
> >    U32 closest = 0;
> >    F32 closestDepth = contacts[0].depth;
> >    for (U32 i = 1; i < c; i++)
> >    {
> >       if (contacts[i].depth < closestDepth)
> >       {
> >          closest = i;
> >          closestDepth = contacts[i].depth;
> >       }
> >    }
> >
> >    // Ray intersected world, so get intersection info.
> >    dContactGeom& closestContact = contacts[closest];
> >    result.object = (SceneObject*)dGeomGetData( closestContact.g2 );
> >    result.geom = closestContact.g2;
> >    result.entityType = dGeomGetCategoryBits( closestContact.g2 );
> >    result.point.set( closestContact.pos[0], closestContact.pos[1],
> > closestContact.pos[2] );
> >    result.normal.set( closestContact.normal[0], closestContact.normal[1],
> > closestContact.normal[2] );
> >    result.distance = closestContact.depth;
> >
> >    return true;
> > }
> >
> >
>
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