public override bool FindIntersection(Ray ray, out Intersection intersect)
{
intersect = new Intersection();
const float A = 1.0f;
Vector3D viewPosRel = ray.Origin - this.center; // Origin relative to center
float udotp = (ray.Direction * viewPosRel);
float B = (udotp + udotp + udotp + udotp);
float RadiiSqSum = this.majorRadius2 + this.minorRadius2;
float ucdotp = (this.axisC * viewPosRel);
float ucdotu = (this.axisC * ray.Direction);
float pSq = (viewPosRel * viewPosRel);
float C = B * udotp + (pSq + pSq) - (RadiiSqSum + RadiiSqSum) + 4.0f * this.majorRadius2 * ucdotu * ucdotu;
float D = 4.0f * ((pSq - RadiiSqSum) * udotp + (this.majorRadius2 + this.majorRadius2) * ucdotp * ucdotu);
float E = (pSq - (RadiiSqSum + RadiiSqSum)) * pSq + 4.0f * this.majorRadius2 * ucdotp * ucdotp +
((this.majorRadius2 - this.minorRadius2) * (this.majorRadius2 - this.minorRadius2));
float[] roots = { 0f, 0f, 0f, 0f };
int numRoots = EquationSolver.SolveQuartic(A, B, C, D, E, out roots[0], out roots[1], out roots[2],
out roots[3]);
//if (numRoots > 0)
//{
// Debug.WriteLine(ray.Direction.ToString());
//}
//if (numRoots > 0)
//Debug.Write(String.Format("A={0},B={1},C={2},D={3},E={4} - ", A, B, C, D, E));
//for (int i = 0; i < numRoots; i++)
//{
// Debug.Write(roots[i] + "|");
//}
//if (numRoots > 0)
// Debug.Write("\r\n");
if (numRoots > 0)
{
if (roots[0] > 0.1f)
{
intersect.TMin = roots[0];
intersect.HitPoint = ray.Origin + intersect.TMin * ray.Direction;
// Intersection position (not relative to center)
intersect.HitPrimitive = this;
// Outward normal
Vector3D h = intersect.HitPoint - this.center; // Now its the relative point
float xCoord = h * this.axisA; // forward axis
float yCoord = h * this.axisB; // rightward axis
float zCoord = h * this.axisC; // upward axis
intersect.Normal = this.axisC * -zCoord + h;
float outNnorm = intersect.Normal.Length;
intersect.Normal.Normalize();
intersect.Normal = intersect.Normal * -this.majorRadius + h;
// Negative point projected to center path of torus
intersect.Normal.Normalize(); // Fix roundoff error problems
if (this.material != null && this.material.IsTexturized)
{
// u - v coordinates
double u = Math.Atan2(yCoord, xCoord);
u = u * (0.5 / Math.PI) + 0.5;
double bVal = outNnorm - this.majorRadius;
double v = Math.Atan2(zCoord, bVal);
v = v * (0.5 / Math.PI) + 0.5;
//int widthTex = this.material.Texture.Width - 1;
//int heightTex = this.material.Texture.Height - 1;
//this.material.Color = this.material.Texture.GetPixel((int)(u * widthTex), (int)(v * heightTex));
intersect.CurrentTextureCoordinate.U = (float)u;
intersect.CurrentTextureCoordinate.V = (float)v;
}
return(true);
}
}
return(false);
}