bool CPlane::Intersects(Real& f_t_on_ray,
const CRay3& c_ray) {
/* Ray direction */
CVector3 cRayDir;
c_ray.GetDirection(cRayDir);
/* Calculate f_t_on_ray */
Real fNumerator = (m_cPosition-c_ray.GetStart()).DotProduct(m_cNormal);
Real fDenominator = cRayDir.DotProduct(m_cNormal);
/* Is ray parallel to plane? */
if(Abs(fDenominator) > 1e-6) {
/* No, it's not */
f_t_on_ray = fNumerator / fDenominator / c_ray.GetLength();
return (f_t_on_ray < 1.0f);
}
else {
/* Yes, it is */
/* Is ray coincident with the plane? */
if(Abs(fNumerator) > 1e-6) {
/* No, the ray is parallel to and far from the plane */
/* No intersection possible */
return false;
}
else {
/* Yes, the ray coincides with the plane */
f_t_on_ray = 0.0f;
return true;
}
}
}
/**
* Check for ray intersection
*/
bool CBulletSphereModel::CheckIntersectionWithRay(Real &f_t_on_ray, const CRay3 &ray) const
{
CVector3 rayOrigin = ray.GetStart();
CVector3 rayDirection;
ray.GetDirection(rayDirection);
CVector3 sourceToOrigin = rayOrigin - position;
double sourceToOriginLength = sourceToOrigin.Length();
double lineDotSourceToOrigin = rayDirection.DotProduct(sourceToOrigin);
double solutionCheck = pow(lineDotSourceToOrigin, 2);
solutionCheck -= pow(sourceToOriginLength, 2);
solutionCheck += pow(entity->GetRadius(), 2);
if(solutionCheck < 0)
return false;
f_t_on_ray = -lineDotSourceToOrigin - sqrt(solutionCheck);
return true;
}
bool CCylinder::Intersects(Real& f_t_on_ray,
const CRay3& c_ray) {
/*
* This algorithm was adapted from
* http://www.realtimerendering.com/resources/GraphicsGems/gemsiv/ray_cyl.c
*/
/* Vector from cylinder base to ray start */
CVector3 cCylBase2RayStart(c_ray.GetStart());
cCylBase2RayStart -= m_cBasePos;
/* Ray direction and length */
CVector3 cRayDir;
c_ray.GetDirection(cRayDir);
Real fRayLen = c_ray.GetLength();
/* Vector normal to cylinder axis and ray direction */
CVector3 cNormal(cRayDir);
cNormal.CrossProduct(m_cAxis);
Real fNormalLen = cNormal.Length();
/* Are cylinder axis and ray parallel? */
if(fNormalLen > 0) {
/* No, they aren't parallel */
/* Make normal have length 1 */
cNormal /= fNormalLen;
/* Calculate shortest distance between axis and ray
* by projecting cCylBase2RayStart onto cNormal */
Real fDist = Abs(cCylBase2RayStart.DotProduct(cNormal));
/* Is fDist smaller than the cylinder radius? */
if(fDist > m_fRadius) {
/* No, it's not, so there can't be any intersection */
return false;
}
/* If we get here, it's because the ray intersects the infinite cylinder */
/* Create a buffer for the 4 potential intersection points
(two on the sides, two on the bases) */
Real fPotentialT[4];
/* First, calculate the intersection points with the sides */
/* Calculate the midpoint between the two intersection points */
CVector3 cVec(cCylBase2RayStart);
cVec.CrossProduct(m_cAxis);
Real fMidPointDist = -cVec.DotProduct(cNormal) / fNormalLen;
/* Calculate the distance between the midpoint and the potential t's */
cVec = cNormal;
cVec.CrossProduct(m_cAxis);
cVec.Normalize();
Real fDeltaToMidPoint = Abs(Sqrt(Square(m_fRadius) - Square(fDist)) / cRayDir.DotProduct(cVec));
/* Calculate the potential t's on the infinite surface */
fPotentialT[0] = (fMidPointDist - fDeltaToMidPoint) / fRayLen;
fPotentialT[1] = (fMidPointDist + fDeltaToMidPoint) / fRayLen;
/* Make sure these t's correspond to points within the cylinder bases */
CVector3 cPoint;
c_ray.GetPoint(cPoint, fPotentialT[0]);
if((cPoint - m_cBasePos).DotProduct(m_cAxis) < 0 ||
(cPoint - (m_cBasePos + m_fHeight * m_cAxis)).DotProduct(m_cAxis) > 0) {
fPotentialT[0] = -1;
}
c_ray.GetPoint(cPoint, fPotentialT[1]);
if((cPoint - m_cBasePos).DotProduct(m_cAxis) < 0 ||
(cPoint - (m_cBasePos + m_fHeight * m_cAxis)).DotProduct(m_cAxis) > 0) {
fPotentialT[1] = -1;
}
/* Check whether the ray is contained within the cylinder bases */
Real fDenominator = cRayDir.DotProduct(m_cAxis);
/* Is ray parallel to plane? */
if(Abs(fDenominator) > 1e-6) {
/* No, it's not parallel */
fDenominator *= fRayLen;
/* Bottom base */
fPotentialT[2] =
(m_cBasePos - c_ray.GetStart()).DotProduct(m_cAxis) / fDenominator;
/* Top base */
fPotentialT[3] =
(m_cBasePos + m_fHeight * m_cAxis - c_ray.GetStart()).DotProduct(m_cAxis) / fDenominator;
/* Make sure these t's are within the cylinder surface */
c_ray.GetPoint(cPoint, fPotentialT[2]);
CVector3 cDiff = cPoint - m_cBasePos;
if((cDiff - cDiff.DotProduct(m_cAxis) * m_cAxis).SquareLength() > Square(m_fRadius))
fPotentialT[2] = -1;
c_ray.GetPoint(cPoint, fPotentialT[3]);
cDiff = cPoint - m_cBasePos;
if((cDiff - cDiff.DotProduct(m_cAxis) * m_cAxis).SquareLength() > Square(m_fRadius))
fPotentialT[3] = -1;
}
else {
/* Yes, it's parallel - discard the intersections */
fPotentialT[2] = -1.0;
fPotentialT[3] = -1.0;
}
/* Go through all the potential t's and get the best */
f_t_on_ray = 2.0;
for(UInt32 i = 0; i < 4; ++i) {
if(fPotentialT[i] > 0.0f) {
f_t_on_ray = Min(f_t_on_ray, fPotentialT[i]);
}
}
/* Return true only if the intersection point is within the ray limits */
return (f_t_on_ray < 1.0f);
}
else {
/* Yes, ray and axis are parallel */
/* Projection of cCylBase2RayStart onto the axis */
Real fProj = cCylBase2RayStart.DotProduct(m_cAxis);
/* Radial vector */
CVector3 cRadial(cCylBase2RayStart);
cRadial -= fProj * m_cAxis;
Real fDist = cRadial.Length();
/* Is ray within the cylinder radius? */
if(fDist > m_fRadius) {
/* No, it's not */
return false;
}
/* If we get here, it's because the ray might intersect the cylinder bases */
Real fDenominator = cRayDir.DotProduct(m_cAxis) * fRayLen;
/* Create a buffer for the 2 potential intersection points */
Real fPotentialT[2];
/* Bottom base */
fPotentialT[0] =
(m_cBasePos-c_ray.GetStart()).DotProduct(m_cAxis) / fDenominator;
/* Top base */
fPotentialT[1] =
(m_cBasePos + m_fHeight * m_cAxis - c_ray.GetStart()).DotProduct(m_cAxis) / fDenominator;
/* Make sure these t's are within the cylinder surface */
CVector3 cPoint;
c_ray.GetPoint(cPoint, fPotentialT[0]);
CVector3 cDiff = cPoint - m_cBasePos;
if((cDiff - cDiff.DotProduct(m_cAxis) * m_cAxis).SquareLength() > Square(m_fRadius))
fPotentialT[0] = -1;
c_ray.GetPoint(cPoint, fPotentialT[1]);
cDiff = cPoint - m_cBasePos;
if((cDiff - cDiff.DotProduct(m_cAxis) * m_cAxis).SquareLength() > Square(m_fRadius))
fPotentialT[1] = -1;
/* Go through all the potential t's and get the best */
f_t_on_ray = 2.0;
for(UInt32 i = 0; i < 2; ++i) {
if(fPotentialT[i] > 0.0f) {
f_t_on_ray = Min(f_t_on_ray, fPotentialT[i]);
}
}
/* Return true only if the intersection point is within the ray limits */
return (f_t_on_ray < 1.0f);
}
}
