bool btSphereBoxCollisionAlgorithm::getSphereDistance(const btCollisionObjectWrapper* boxObjWrap, btVector3& pointOnBox, btVector3& normal, btScalar& penetrationDepth, const btVector3& sphereCenter, btScalar fRadius, btScalar maxContactDistance )
{
const btBoxShape* boxShape= (const btBoxShape*)boxObjWrap->getCollisionShape();
btVector3 const &boxHalfExtent = boxShape->getHalfExtentsWithoutMargin();
btScalar boxMargin = boxShape->getMargin();
penetrationDepth = 1.0f;
// convert the sphere position to the box's local space
btTransform const &m44T = boxObjWrap->getWorldTransform();
btVector3 sphereRelPos = m44T.invXform(sphereCenter);
// Determine the closest point to the sphere center in the box
btVector3 closestPoint = sphereRelPos;
closestPoint.setX( btMin(boxHalfExtent.getX(), closestPoint.getX()) );
closestPoint.setX( btMax(-boxHalfExtent.getX(), closestPoint.getX()) );
closestPoint.setY( btMin(boxHalfExtent.getY(), closestPoint.getY()) );
closestPoint.setY( btMax(-boxHalfExtent.getY(), closestPoint.getY()) );
closestPoint.setZ( btMin(boxHalfExtent.getZ(), closestPoint.getZ()) );
closestPoint.setZ( btMax(-boxHalfExtent.getZ(), closestPoint.getZ()) );
btScalar intersectionDist = fRadius + boxMargin;
btScalar contactDist = intersectionDist + maxContactDistance;
normal = sphereRelPos - closestPoint;
//if there is no penetration, we are done
btScalar dist2 = normal.length2();
if (dist2 > contactDist * contactDist)
{
return false;
}
btScalar distance;
//special case if the sphere center is inside the box
if (dist2 == 0.0f)
{
distance = -getSpherePenetration(boxHalfExtent, sphereRelPos, closestPoint, normal);
}
else //compute the penetration details
{
distance = normal.length();
normal /= distance;
}
pointOnBox = closestPoint + normal * boxMargin;
// v3PointOnSphere = sphereRelPos - (normal * fRadius);
penetrationDepth = distance - intersectionDist;
// transform back in world space
btVector3 tmp = m44T(pointOnBox);
pointOnBox = tmp;
// tmp = m44T(v3PointOnSphere);
// v3PointOnSphere = tmp;
tmp = m44T.getBasis() * normal;
normal = tmp;
return true;
}
btScalar btSphereBoxCollisionAlgorithm::getSphereDistance(btCollisionObject* boxObj, btVector3& pointOnBox, btVector3& v3PointOnSphere, const btVector3& sphereCenter, btScalar fRadius )
{
btScalar margins;
btVector3 bounds[2];
btBoxShape* boxShape= (btBoxShape*)boxObj->getCollisionShape();
bounds[0] = -boxShape->getHalfExtentsWithoutMargin();
bounds[1] = boxShape->getHalfExtentsWithoutMargin();
margins = boxShape->getMargin();//also add sphereShape margin?
const btTransform& m44T = boxObj->getWorldTransform();
btVector3 boundsVec[2];
btScalar fPenetration;
boundsVec[0] = bounds[0];
boundsVec[1] = bounds[1];
btVector3 marginsVec( margins, margins, margins );
// add margins
bounds[0] += marginsVec;
bounds[1] -= marginsVec;
/////////////////////////////////////////////////
btVector3 tmp, prel, n[6], normal, v3P;
btScalar fSep = btScalar(10000000.0), fSepThis;
n[0].setValue( btScalar(-1.0), btScalar(0.0), btScalar(0.0) );
n[1].setValue( btScalar(0.0), btScalar(-1.0), btScalar(0.0) );
n[2].setValue( btScalar(0.0), btScalar(0.0), btScalar(-1.0) );
n[3].setValue( btScalar(1.0), btScalar(0.0), btScalar(0.0) );
n[4].setValue( btScalar(0.0), btScalar(1.0), btScalar(0.0) );
n[5].setValue( btScalar(0.0), btScalar(0.0), btScalar(1.0) );
// convert point in local space
prel = m44T.invXform( sphereCenter);
bool bFound = false;
v3P = prel;
for (int i=0;i<6;i++)
{
int j = i<3? 0:1;
if ( (fSepThis = ((v3P-bounds[j]) .dot(n[i]))) > btScalar(0.0) )
{
v3P = v3P - n[i]*fSepThis;
bFound = true;
}
}
//
if ( bFound )
{
bounds[0] = boundsVec[0];
bounds[1] = boundsVec[1];
normal = (prel - v3P).normalize();
pointOnBox = v3P + normal*margins;
v3PointOnSphere = prel - normal*fRadius;
if ( ((v3PointOnSphere - pointOnBox) .dot (normal)) > btScalar(0.0) )
{
return btScalar(1.0);
}
// transform back in world space
tmp = m44T( pointOnBox);
pointOnBox = tmp;
tmp = m44T( v3PointOnSphere);
v3PointOnSphere = tmp;
btScalar fSeps2 = (pointOnBox-v3PointOnSphere).length2();
//if this fails, fallback into deeper penetration case, below
if (fSeps2 > SIMD_EPSILON)
{
fSep = - btSqrt(fSeps2);
normal = (pointOnBox-v3PointOnSphere);
normal *= btScalar(1.)/fSep;
}
return fSep;
}
//////////////////////////////////////////////////
// Deep penetration case
fPenetration = getSpherePenetration( boxObj,pointOnBox, v3PointOnSphere, sphereCenter, fRadius,bounds[0],bounds[1] );
bounds[0] = boundsVec[0];
bounds[1] = boundsVec[1];
if ( fPenetration <= btScalar(0.0) )
return (fPenetration-margins);
else
return btScalar(1.0);
}
