/// <summary>
/// Creates a translation matrix.
/// </summary>
public static Matrix Translation(EVector vec)
{
return(new Matrix(new EVector(1, 0, 0),
new EVector(0, 1, 0),
new EVector(0, 0, 1),
vec));
}
/// <summary>
/// Creates a possibly non-uniform scaling matrix.
/// </summary>
public static Matrix Scaling(EVector scale)
{
return(new Matrix(new EVector(scale.X, 0, 0),
new EVector(0, scale.Y, 0),
new EVector(0, 0, scale.Z),
EVector.Zero));
}
/// <summary>
/// Constructs a matrix from four column vectors.
/// </summary>
private Matrix(EVector u, EVector v, EVector w, EVector t)
{
this.u = u;
this.v = v;
this.w = w;
this.t = t;
}
private static Tuple <Ray, float> RayFromVertices(Point3f a, Point3f b)
{
EPoint pt = new EPoint(a.X, a.Y, a.Z);
EVector vec = new EVector(b.X - a.X, b.Y - a.Y, b.Z - a.Z);
Ray ray = new Ray(pt, vec);
float mag = EVector.Length(vec);
return(new Tuple <Ray, float>(ray, mag));
}
/// <summary>
/// Returns the azimuth of a vector.
/// </summary>
/// <remarks>
/// Horizontal angle, zero towards the z-axis.
/// </remarks>
public static float Azimuth(EVector u)
{
var len = Length(u);
if (len > 0)
{
return((float)Math.Atan2(u.Z, u.X));
}
else
{
throw new InvalidOperationException("Vector has no direction");
}
}
/// <summary>
/// Returns the inclination of a vector.
/// </summary>
/// <remarks>
/// Vertical angle, zero on the xz-plane.
/// </remarks>
public static float Inclination(EVector u)
{
var len = Length(u);
if (len > 0)
{
return((float)(Math.Acos(u.Y / len) - Math.PI / 2));
}
else
{
throw new InvalidOperationException("Vector has no direction");
}
}
/// <summary>
/// Normalizes a vector to unit length.
/// </summary>
public static EVector Normalize(EVector u)
{
var len = Length(u);
if (len > 0)
{
return(u / len);
}
else
{
throw new InvalidOperationException("Vector has no direction");
}
}
/// <summary>
/// Returns the inverse of a matrix.
/// </summary>
public static Matrix Invert(Matrix mat)
{
// Work out determinant of the 3x3 submatrix.
var det = mat.U.X * (mat.V.Y * mat.W.Z - mat.W.Y * mat.V.Z)
- mat.V.X * (mat.W.Z * mat.U.Y - mat.W.Y * mat.U.Z)
+ mat.W.X * (mat.U.Y * mat.V.Z - mat.V.Y * mat.U.Z);
if (Math.Abs(det) < 0)
{
throw new ArgumentException("Matrix is not invertible");
}
// Compute inv(submatrix) = transpose(submatrix) / det.
var inv_u = new EVector(mat.U.X, mat.V.X, mat.W.X) / det;
var inv_v = new EVector(mat.U.Y, mat.V.Y, mat.W.Y) / det;
var inv_w = new EVector(mat.U.Z, mat.V.Z, mat.W.Z) / det;
// Transform the translation column by this inverse matrix.
var inv_t = -(mat.T.X * inv_u + mat.T.Y * inv_v + mat.T.Z * inv_w);
return(new Matrix(inv_u, inv_v, inv_w, inv_t));
}
/// <summary>
/// Constructs a ray with an origin and a direction.
/// </summary>
public Ray(EPoint origin, EVector direction)
{
this.origin = origin;
this.direction = direction.Normalize();
}
/// <summary>
/// Converts a vector into a point.
/// </summary>
/// <remarks>
/// This is meaningless mathematically.
/// </remarks>
public static EPoint ToPoint(EVector u)
{
return(EPoint.Zero + u);
}
/// <summary>
/// Returns the cross product of this vector with another.
/// </summary>
public EVector Cross(EVector v)
{
return(Cross(this, v));
}
/// <summary>
/// Transforms a vector by this matrix.
/// </summary>
public EVector Transform(EVector vec)
{
return(Transform(this, vec));
}
/// <summary>
/// Returns the cross product of two vectors.
/// </summary>
public static EVector Cross(EVector u, EVector v)
{
return(new EVector(u.Y * v.Z - u.Z * v.Y,
u.Z * v.X - u.X * v.Z,
u.X * v.Y - u.Y * v.X));
}
/// <summary>
/// Returns the dot product of two vectors.
/// </summary>
public static float Dot(EVector u, EVector v)
{
return(u.X * v.X + u.Y * v.Y + u.Z * v.Z);
}
/// <summary>
/// Returns the length of a vector.
/// </summary>
public static float Length(EVector u)
{
return((float)Math.Sqrt(Dot(u, u)));
}
/// <summary>
/// Reflects a vector about a normal.
/// </summary>
public static EVector Reflect(EVector i, EVector n)
{
return(i - 2 * n * Dot(i, n));
}
/// <summary>
/// Transforms a vector by a matrix.
/// </summary>
public static EVector Transform(Matrix mat, EVector vec)
{
return(vec.X * mat.U + vec.Y * mat.V + vec.Z * mat.W);
}
/// <summary>
/// Reflects this vector about a normal.
/// </summary>
public EVector Reflect(EVector n)
{
return(Reflect(this, n));
}
/// <summary>
/// Returns the dot product of this vector with another.
/// </summary>
public float Dot(EVector v)
{
return(Dot(this, v));
}
/// <summary>
/// Corrects an Embree.NET normal, which is unnormalized
/// and in object space, to a world space normal vector.
/// </summary>
public EVector CorrectNormal(EVector normal)
{
return((inverseTranspose * normal).Normalize());
}