public IntersectionInfo Intersection(Ray r)
{
Vector3D normal = VectorOperations.VectorProduct(new Vector3D(A, B), new Vector3D(A, C));
normal *= (1 / normal.Length);
Vector3D V = new Vector3D(r.Origin.X - A.X, r.Origin.Y - A.Y, r.Origin.Z - A.Z);
//определяем пересекает ли луч треугольник
double t = -VectorOperations.ScalarProduct(V, normal) / VectorOperations.ScalarProduct(r.Direction, normal);
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(normal, 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) * ((VectorOperations.Cos(OX, AC) < 0)? -1 : 1);
double Cy = VectorOperations.Distance(axis, C) * ((VectorOperations.Cos(OY, AC) < 0)? -1 : 1);
double Dx = VectorOperations.Distance(ordinate, crossPoint) * ((VectorOperations.Cos(OX, AD) < 0)? -1 : 1);
double Dy = VectorOperations.Distance(axis, crossPoint) * ((VectorOperations.Cos(OY, AD) < 0) ? -1 : 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 = ownerSurface.MaterialFront;
if (VectorOperations.Cos(normal, r.Direction) >= -epsilon && (ownerSurface.MaterialBack != null))
{
normal *= (-1);
m = ownerSurface.MaterialBack;
}
return(new IntersectionInfo(crossPoint, normal, m));
}
return(null);
}
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);
}
//public Material Material
//{
// set
// {
// material = value;
// }
//}
public IntersectionInfo Intersection(Ray r)
{
double epsilon = 0.01;
Vector3D v = new Vector3D(r.Origin.X - center.X, r.Origin.Y - center.Y, r.Origin.Z - center.Z);
double A = r.Direction.LengthSquare;
double B = VectorOperations.ScalarProduct(r.Direction, v);
double C = v.LengthSquare - radius * radius;
double D = B * B - A * C;
if (D <= 0.0)
{
return(null);
}
double t1 = (-B - Math.Sqrt(D)) / A;
double t2 = (-B + Math.Sqrt(D)) / A;
double t = t1;
if (t2 <= epsilon)
{
return(null);
}
if (t1 <= epsilon) //луч идет из шара
{
t = t2;
}
Point3D P = new Point3D(r.Origin.X + r.Direction.X * t,
r.Origin.Y + r.Direction.Y * t,
r.Origin.Z + r.Direction.Z * t); //первая точка пересечения
Vector3D N = new Vector3D(center, P); //вектор нормали единичной длины
N *= (1 / N.Length);
if (t1 <= epsilon) //луч идет из шара
{
N *= (-1.0);
}
if (texture != null)
{
Point3D E = new Point3D(P.X - center.X, P.Y - center.Y, P.Z - center.Z);
double psi, fi;
psi = Math.Asin(E.Z / radius);
if (Math.Abs(psi) == Math.PI / 2)
{
fi = 0;
}
else
{
double cosfi = E.X / (radius * Math.Cos(psi));
if (cosfi > 1)
{
cosfi = 1;
}
if (cosfi < -1)
{
cosfi = -1;
}
fi = Math.Acos(cosfi);
if (E.Y < 0)
{
fi = 2 * Math.PI - fi;
}
}
Material m;
lock (texture)
{
int x = (int)((fi / (Math.PI * 2)) * (texture.Width - 1));
int y = (int)((0.5 - psi / Math.PI) * (texture.Height - 1));
m = new Material(texture.GetPixel(x, y), material.Diffusion, material.Specularity,
material.Reflection, material.Transparency, material.FongCoeff);
}
material = m;
}
return(new IntersectionInfo(P, N, material));
}
