public static Vec4D CreateHorizon(Vec4D pole, double z, double theta)
{
Vec4D cross = CreateHorizontal(pole);
//double phi = Math.Acos(z);
//return MatrixTransforms.Rotate(theta, pole) * MatrixTransforms.Rotate(phi, cross) * pole;
return(MatrixTransforms.Rotate(theta, pole) * ((pole * z) + (cross * Math.Sqrt(1 - z * z))));
}
/// <summary>Used to initialize a <see cref="Ray"/> with an already-normalized <paramref name="direction"/> vector.</summary>
public Ray(Vec4D origin, Vec4D direction)
{
Origin = origin;
Direction = direction;
#if DEBUG
Util.AssertNearlyEqual(direction.SquaredLength, 1, 1e-9, "Ray was instantiated with a non-unit direction vector.");
#endif
}
public static Vec4D CreateHorizontal(Vec4D vector)
{
// Cross against a (arbitrary) up vector to create horizontal vector
Vec4D cross = vector.Cross(new Vec4D(0, 0, 1, 0));
// If our up vector matches our input vector, return an arbitrary horizontal
if (cross == new Vec4D(0, 0, 0, 0))
{
return(new Vec4D(1, 0, 0, 0));
}
return(cross.Normalize());
}
public static Mat4x4D Rotate(double angle, Vec4D axis)
{
axis = axis.Normalize();
double cos = Math.Cos(angle);
double sin = Math.Sin(angle);
double cosOpp = 1 - cos;
return(new Mat4x4D(
cos + axis.X * axis.X * cosOpp, axis.X * axis.Y * cosOpp - axis.Z * sin, axis.X * axis.Z * cosOpp + axis.Y * sin, 0,
axis.Y * axis.X * cosOpp + axis.Z * sin, cos + axis.Y * axis.Y * cosOpp, axis.Y * axis.Z * cosOpp - axis.X * sin, 0,
axis.Z * axis.X * cosOpp - axis.Y * sin, axis.Z * axis.Y * cosOpp + axis.X * sin, cos + axis.Z * axis.Z * cosOpp, 0,
0, 0, 0, 1));
}
/// <summary>Create a directional ray starting from <paramref name="origin"/>. The <paramref name="direction"/> vector will be normalized.</summary>
public static Ray Directional(Vec4D origin, Vec4D direction)
{
return(new Ray(origin, direction.Normalize()));
}
/// <summary>Returns a ray starting from <paramref name="origin"/> and extending infinitely toward the <paramref name="end"/> point.</summary>
public static Ray FromTo(Vec4D origin, Vec4D end)
{
return(new Ray(origin, (end - origin).Normalize()));
}