bool CUtils::IntersectTriangle(const CRay &i_Ray,
CIntersactionInfo &io_IntersectionInfo,
const CVector3DF &i_vA,
const CVector3DF &i_vB,
const CVector3DF &i_vC)
{
//intersect stuff
double lambda2;
double lambda3;
double closestdist = io_IntersectionInfo.m_fDistance;
const CVector3DF a = i_vB - i_vA;
const CVector3DF b = i_vC - i_vA;
CVector3DF c = - (i_Ray.Direction());
CVector3DF h = i_Ray.StartPoint() - i_vA;
/* 2. Solve the equation:
*
* A + lambda2 * AB + lambda3 * AC = ray.start + gamma * ray.dir
*
* which can be rearranged as:
* lambda2 * AB + lambda3 * AC - gamma * ray.dir = ray.start - A
*
* Which is a linear system of three rows and three unknowns, which we solve using Carmer's rule
*/
//
// Find the determinant of the left part of the equation
const float Dcr = CVector3DF::Triple(a, b, c);
// check for zero; if it is zero, then the triangle and the ray are parallel
if (fabs(Dcr) < k_fSMALL)
{
return false;
}
// find the reciprocal of the determinant. We would use this quantity later in order
// to multiply by rDcr instead of divide by Dcr (division is much slower)
double rDcr = 1.0 / Dcr;
// calculate `gamma' by substituting the right part of the equation in the third column of the matrix,
// getting the determinant, and dividing by Dcr)
const double gamma = CVector3DF::Triple(a, b, h) * rDcr;
// Is the intersection point behind us? Is the intersection point worse than what we currently have?
if (gamma <= 0 || gamma > closestdist)
{
return false;
}
lambda2 = CVector3DF::Triple(h, b, c) * rDcr;
// Check if it is in range (barycentric coordinates)
if (lambda2 < 0 || lambda2 > 1)
{
return false;
}
lambda3 = CVector3DF::Triple(a, h, c) * rDcr;
// Calculate lambda3 and check if it is in range as well
if (lambda3 < 0 || lambda3 > 1)
{
return false;
}
if (lambda2 + lambda3 > 1)
{
return false;
}
closestdist = gamma;
io_IntersectionInfo.m_fDistance = closestdist;
io_IntersectionInfo.m_vIntersectionPoint = i_Ray.GetPointAtDistance(closestdist);
io_IntersectionInfo.m_vBarCoordsLocal.SetX(1.0f - lambda2 - lambda3);
io_IntersectionInfo.m_vBarCoordsLocal.SetY(lambda2);
io_IntersectionInfo.m_vBarCoordsLocal.SetZ(lambda3);
//Normal to the surface
io_IntersectionInfo.m_vNormal = CVector3DF::Normal(a, b);
return true;
}
bool CBezierPatch::intersect(const CRay &ray, CIntersactionInfo &info, CVector3DF barCoord, unsigned int iterations, bool bDebug) const
{
//Planes along ray
CVector3DF N1 = ray.Direction().Cross(CVector3DF(-1.0f,-1.0f,-1.0f));
CVector3DF N2 = ray.Direction().Cross(N1);
const float d1 = -N1.Dot(ray.StartPoint());
const float d2 = -N2.Dot(ray.StartPoint());
float fSMall = 1e-3;
CVector3DF dBu, dBv;
for (unsigned int i = 0; i < iterations; i++)
{
const double &u(barCoord.X());
const double &v(barCoord.Y());
//partial U derivative of B
dBu = GetdBu(u,v);
//Partial V derivative of B
dBv = GetdBv(u,v);
const CVector3DF B = GetPointFromBarycentric(barCoord);
const CVector3DF R = CVector3DF(N1.Dot(B) + d1,
N2.Dot(B) + d2,
0);
if ( ( fabs(R.X()) < fSMall ) &&
( fabs(R.Y()) < fSMall ) )
{
break;
}
//Inverse Jacobian
const float fN1dotdBu = N1.Dot(dBu);
const float fN1dotdBv = N1.Dot(dBv);
const float fN2dotdBu = N2.Dot(dBu);
const float fN2dotdBv = N2.Dot(dBv);
const float invConst = 1.0f / ( fN1dotdBu * fN2dotdBv - fN1dotdBv * fN2dotdBu );
Matrix inverseJacobian;
inverseJacobian[0][0] = fN2dotdBv * invConst;
inverseJacobian[0][1] = -fN2dotdBu * invConst;
inverseJacobian[0][2] = 0;
inverseJacobian[1][0] = -fN1dotdBv * invConst;
inverseJacobian[1][1] = fN1dotdBu * invConst;
inverseJacobian[1][2] = 0;
inverseJacobian[2][0] = 0;
inverseJacobian[2][1] = 0;
inverseJacobian[2][2] = 1;
//Newton Iteration
barCoord = barCoord - R.MatrixMultiply(inverseJacobian);
barCoord.SetZ(1.0 - barCoord.X() - barCoord.Y());
if (barCoord.X() > k_fMAX || barCoord.X() < k_fMIN
|| barCoord.Y() > k_fMAX || barCoord.Y() < k_fMIN
|| barCoord.Z() > k_fMAX || barCoord.Z() < k_fMIN)
{
return false;
}
}
const float &u(barCoord.X());
const float &v(barCoord.Y());
const float w(1.0 - u - v);
if (u < -k_fSMALL || u > 1.0f + k_fSMALL
|| v < -k_fSMALL || v > 1.0f + k_fSMALL
|| w < -k_fSMALL || w > 1.0f + k_fSMALL)
{
return false;
}
if (bDebug)
{
char str[100];
sprintf( str, "u: %4.2f v: %4.2f w: %4.2f", u, v, w);
qDebug() << str;
}
//Calculating B
const CVector3DF B = GetPointFromBarycentric(barCoord);
if ( ( fabs(N1.Dot(B) + d1) > fSMall ) ||
( fabs(N2.Dot(B) + d2) > fSMall ) )
{
if (bDebug)
{
qDebug() << "error too big";
}
return false;
}
// calculate the intersection
float len = (B - ray.StartPoint()).Length();
if (len > info.m_fDistance)
{
if (bDebug)
{
qDebug() << "Len > Distance";
}
return false;
}
info.m_vIntersectionPoint = B;
info.m_fDistance = len;
info.m_vBarCoordsLocal.SetX(u);
info.m_vBarCoordsLocal.SetY(v);
info.m_vBarCoordsLocal.SetZ(w);
info.m_vBarCoordsGlobal = info.m_vBarCoordsLocal;
if (GetSettings()->m_bNormalSmoothing)
{
info.m_vNormal = GetSmoothedNormal(barCoord);
}
else
{
// info.m_vNormal = GetSmoothedNormal(barCoord);
info.m_vNormal = CVector3DF::Normal(dBu, dBv);
}
if (bDebug)
{
qDebug()<< "Patch Hit!";
}
return true;
}
bool CAABox::Intersect(const CRay &ray, bool bDebug) const
{
if (IsInside(ray.StartPoint()))
{
return true;
}
//if (bDebug)
//{
// CIntersactionInfo IntersectionInfo;
// return Intersect_Test(ray, IntersectionInfo, bDebug);
//}
//create needed data for intersection
float aRayDir[3], aRayStart[3], aRayRevDir[3], aVMin[3], aVMax[3];
for (int i = 0; i < 3; ++i)
{
const CVector3DF::EDimiensions eDim = (CVector3DF::EDimiensions) i;
aRayDir[i] = ray.Direction().GetDimension(eDim);
aRayStart[i] = ray.StartPoint().GetDimension(eDim);
aVMin[i] = m_vMinVertex.GetDimension(eDim);
aVMax[i] = m_vMaxVertex.GetDimension(eDim);
aRayRevDir[i] = fabs(aRayDir[i]) > 1e-9 ? 1.0/ aRayDir[i] : 0.f;
};
for (int dim = 0; dim < 3; dim++)
{
if ((aRayDir[dim] < 0 && aRayStart[dim] < aVMin[dim]) || (aRayDir[dim] > 0 && aRayStart[dim] > aVMax[dim]))
{
continue;
}
if (fabs(aRayDir[dim]) < 1e-9)
{
continue;
}
const double& mul = aRayRevDir[dim];
int u = (dim == 0) ? 1 : 0;
int v = (dim == 2) ? 1 : 2;
double dist, x, y;
dist = (aVMin[dim] - aRayStart[dim]) * mul;
if (dist < 0)
{
continue;
}
/* (*) this is a good optimization I found out by chance. Consider the following scenario
*
* ---+ ^ (ray)
* | \
* bbox | \
* | \
* | * (camera)
* -----+
*
* if we're considering the walls up and down of the bbox (which belong to the same axis),
* the optimization in (*) says that we can skip testing with the "up" wall, if the "down"
* wall is behind us. The rationale for that is, that we can never intersect the "down" wall,
* and even if we have the chance to intersect the "up" wall, we'd be intersection the "right"
* wall first. So we can just skip any further intersection tests for this axis.
* This may seem bogus at first, as it doesn't work if the camera is inside the BBox, but then we would
* have quitted the function because of the inside(aRayStart) condition in the first line of the function.
*/
x = aRayStart[u] + aRayDir[u] * dist;
const float fMinX = aVMin[u] - k_fSMALL;
const float fMaxX = aVMax[u] + k_fSMALL;
const float fMinY = aVMin[v] - k_fSMALL;
const float fMaxY = aVMax[v] + k_fSMALL;
if (fMinX <= x && x <= fMaxX)
{
y = aRayStart[v] + aRayDir[v] * dist;
if (fMinY <= y && y <= fMaxY)
{
if ( bDebug )
{
// qDebug() << "A Success Dim: "<< (EDimiensions)dim <<"X: "<< fMinX << x << fMaxX << "Y: " << fMinY << y << fMaxY;
}
return true;
}
if ( bDebug )
{
// qDebug() << "A Fail Dim: "<< (EDimiensions)dim <<"X: "<< fMinX << x << fMaxX << "Y: " << fMinY << y << fMaxY;
}
}
dist = (aVMax[dim] - aRayStart[dim]) * mul;
if (dist < 0)
{
continue;
}
x = aRayStart[u] + aRayDir[u] * dist;
if (fMinX <= x && x <= fMaxX)
{
y = aRayStart[v] + aRayDir[v] * dist;
if (fMinY <= y && y <= fMaxY)
{
if ( bDebug )
{
// qDebug() << "B Success Dim: "<< (EDimiensions)dim <<"X: "<< fMinX << x << fMaxX << "Y: " << fMinY << y << fMaxY;
}
return true;
}
if ( bDebug )
{
// qDebug() << "B Fail Dim: "<< (EDimiensions)dim <<"X: "<< fMinX << x << fMaxX << "Y: " << fMinY << y << fMaxY;
}
}
}
return false;
}