public static float SqrDistance(ref Ray3 rkRay, ref Segment3 rkSeg, out float pfRayP, out float pfSegP)
{
Vector3 kDiff = rkRay.Origin - rkSeg.Origin;
float fA00 = rkRay.Direction.length2();
float fA01 = -rkRay.Direction.dot(ref rkSeg.Direction);
float fA11 = rkSeg.Direction.length2();
float fB0 = kDiff.dot(ref rkRay.Direction);
float fC = kDiff.length2();
float fDet = System.Math.Abs(fA00 * fA11 - fA01 * fA01);
float fB1, fS, fT, fSqrDist, fTmp;
if (fDet >= gs_fTolerance)
{
// ray and segment are not parallel
fB1 = -kDiff.dot(ref rkSeg.Direction);
fS = fA01 * fB1 - fA11 * fB0;
fT = fA01 * fB0 - fA00 * fB1;
if (fS >= 0.0)
{
if (fT >= 0.0)
{
if (fT <= fDet) // region 0
{
// minimum at interior points of ray and segment
float fInvDet = 1.0f / fDet;
fS *= fInvDet;
fT *= fInvDet;
fSqrDist = fS * (fA00 * fS + fA01 * fT + 2.0f * fB0) +
fT * (fA01 * fS + fA11 * fT + 2.0f * fB1) + fC;
}
else // region 1
{
fT = 1.0f;
if (fB0 >= -fA01)
{
fS = 0.0f;
fSqrDist = fA11 + 2.0f * fB1 + fC;
}
else
{
fTmp = fA01 + fB0;
fS = -fTmp / fA00;
fSqrDist = fTmp * fS + fA11 + 2.0f * fB1 + fC;
}
}
}
else // region 5
{
fT = 0.0f;
if (fB0 >= 0.0)
{
fS = 0.0f;
fSqrDist = fC;
}
else
{
fS = -fB0 / fA00;
fSqrDist = fB0 * fS + fC;
}
}
}
else
{
if (fT <= 0.0) // region 4
{
if (fB0 < 0.0)
{
fS = -fB0 / fA00;
fT = 0.0f;
fSqrDist = fB0 * fS + fC;
}
else
{
fS = 0.0f;
if (fB1 >= 0.0)
{
fT = 0.0f;
fSqrDist = fC;
}
else if (-fB1 >= fA11)
{
fT = 1.0f;
fSqrDist = fA11 + 2.0f * fB1 + fC;
}
else
{
fT = -fB1 / fA11;
fSqrDist = fB1 * fT + fC;
}
}
}
else if (fT <= fDet) // region 3
{
fS = 0.0f;
if (fB1 >= 0.0)
{
fT = 0.0f;
fSqrDist = fC;
}
else if (-fB1 >= fA11)
{
fT = 1.0f;
fSqrDist = fA11 + 2.0f * fB1 + fC;
}
else
{
fT = -fB1 / fA11;
fSqrDist = fB1 * fT + fC;
}
}
else // region 2
{
fTmp = fA01 + fB0;
if (fTmp < 0.0)
{
fS = -fTmp / fA00;
fT = 1.0f;
fSqrDist = fTmp * fS + fA11 + 2.0f * fB1 + fC;
}
else
{
fS = 0.0f;
if (fB1 >= 0.0)
{
fT = 0.0f;
fSqrDist = fC;
}
else if (-fB1 >= fA11)
{
fT = 1.0f;
fSqrDist = fA11 + 2 * fB1 + fC;
}
else
{
fT = -fB1 / fA11;
fSqrDist = fB1 * fT + fC;
}
}
}
}
}
else
{
// ray and segment are parallel
if (fA01 > 0.0)
{
// opposite direction vectors
fT = 0.0f;
if (fB0 >= 0.0)
{
fS = 0.0f;
fSqrDist = fC;
}
else
{
fS = -fB0 / fA00;
fSqrDist = fB0 * fS + fC;
}
}
else
{
// same direction vectors
fB1 = -kDiff.dot(ref rkSeg.Direction);
fT = 1.0f;
fTmp = fA01 + fB0;
if (fTmp >= 0.0)
{
fS = 0.0f;
fSqrDist = fA11 + 2.0f * fB1 + fC;
}
else
{
fS = -fTmp / fA00;
fSqrDist = fTmp * fS + fA11 + 2.0f * fB1 + fC;
}
}
}
pfRayP = fS;
pfSegP = fT;
return(System.Math.Abs(fSqrDist));
}
public static float SqrDistance(ref Ray3 rkRay, ref Segment3 rkSeg)
{
float rayP = 0.0f, segP = 0.0f;
return(SqrDistance(ref rkRay, ref rkSeg, out rayP, out segP));
}
