//given a capsule specified with a transform, two points, and a radius, this will approximate how much is submerged
//and distribute that force to the appropriate points on the capsule
static bool ApplyCapsuleBuoyancy(const LTVector& vPt1, const LTVector& vPt2, float fLength, float fRadius,
const LTPlane& WSPlane, float& fVolume, LTVector& vApplyAt,
float& fSurfaceArea)
{
//convert the capsule to an OBB and apply it
//determine information about the main axis
LTVector vMainAxis = vPt2 - vPt1;
LTASSERT( fLength > 0.0f, "Invalid capsule length." );
LTVector vUnitAxis = vMainAxis / fLength;
//we can now build up a rotation given the plane normal and the axis to build our transform
LTVector vUp = WSPlane.Normal();
if(fabsf(vUp.Dot(vUnitAxis)) > 0.99f)
{
//too close to use, built an arbitrary orthonormal
vUp = vUnitAxis.BuildOrthonormal();
}
LTMatrix3x4 mTemp;
LTVector vRight = vUnitAxis.Cross(vUp);
vRight.Normalize( );
LTVector vTrueUp = vRight.Cross( vUnitAxis );
mTemp.SetBasisVectors(vRight, vTrueUp, vUnitAxis);
LTRotation rRot;
rRot.ConvertFromMatrix(mTemp);
//now we can form our transform
LTRigidTransform tTransform((vPt1 + vPt2) * 0.5f, rRot);
LTVector vHalfDims(fRadius, fRadius, fLength * 0.5f + fRadius);
return ApplyOBBBuoyancy(tTransform, vHalfDims, WSPlane, fVolume, vApplyAt, fSurfaceArea);
}
