static public double Distance(Line3D L, Point3D M)
{
return(VectorProduct(new Vector3D(L.Point, M), L.Direction).Length / L.Direction.Length);
}
public IntersectionInfo Intersection(Ray r)
{
Vector3D N = VectorOperations.VectorProduct(new Vector3D(A, B), new Vector3D(A, C));
//нормаль определяет внешнюю и внутреннюю сторону треугольника
N *= (1 / N.Length);
Vector3D V = new Vector3D(r.Origin.X - A.X,
r.Origin.Y - A.Y,
r.Origin.Z - A.Z);
double t = -VectorOperations.ScalarProduct(V, N) / VectorOperations.ScalarProduct(r.Direction, N);
if (t <= epsilon || Double.IsNaN(t) || Double.IsInfinity(t))
{
return(null);
}
Point3D crossPoint = new Point3D(r.Origin.X + r.Direction.X * t,
r.Origin.Y + r.Direction.Y * t,
r.Origin.Z + r.Direction.Z * t);
Vector3D OX = new Vector3D(A, B);
Vector3D AC = new Vector3D(A, C);
Vector3D AD = new Vector3D(A, crossPoint);
Vector3D OY = VectorOperations.VectorProduct(N, OX);
Line3D axis = new Line3D(A, OX);
Line3D ordinate = new Line3D(A, OY);
double Bx = VectorOperations.Distance(ordinate, B);
double By = 0;
double Cx = VectorOperations.Distance(ordinate, C);
if (VectorOperations.Cos(OX, AC) < 0)
{
Cx *= -1;
}
double Cy = VectorOperations.Distance(axis, C);
if (VectorOperations.Cos(OY, AC) < 0)
{
Cy *= -1;
}
double Dx = VectorOperations.Distance(ordinate, crossPoint);
if (VectorOperations.Cos(OX, AD) < 0)
{
Dx *= -1;
}
double Dy = VectorOperations.Distance(axis, crossPoint);
if (VectorOperations.Cos(OY, AD) < 0)
{
Dy *= -1;
}
int s1 = Math.Sign(Bx * Dy - By * Dx);
int s2 = Math.Sign((Cx - Bx) * (Dy - By) - (Cy - By) * (Dx - Bx));
int s3 = Math.Sign(-Cx * (Dy - Cy) + Cy * (Dx - Cx));
if (s1 == s2 && s1 == s3 && s2 == s3)
{
Material m = material_front;
if (VectorOperations.Cos(N, r.Direction) >= -epsilon && (material_back != null))
{
N *= (-1);
m = material_back;
}
return(new IntersectionInfo(crossPoint, N, m));
}
return(null);
}