/// <summary>
/// Generate a transform that transforms points in a space.
/// </summary>
/// <param name="fromPoints">
/// The "from" points.
/// </param>
/// <param name="toPixels">
/// The "to" points.
/// </param>
/// <returns>
/// The 3x3 matrix that represents a transform from the points to the pixels.
/// </returns>
public static Matrix33 ComputeTransform(IList <Point> fromPoints, IList <Point> toPixels)
{
if (toPixels == null || fromPoints == null)
{
return(null);
}
var pixelMatrix = new Matrix33(toPixels);
var pointMatrix = new Matrix33(fromPoints);
return(pointMatrix.Inverse().Product(pixelMatrix));
}
/// <summary>
/// Generate a transform that transforms points in pc space to locations in map space.
/// </summary>
/// <param name="fromPoints">
/// The "from" points, typically values from a ResourceDictionary entry.
/// </param>
/// <param name="toAnchors">
/// The "to" anchors, typically map locations.
/// </param>
/// <returns>
/// The 3x3 matrix that represents a transform from the points to the anchors.
/// </returns>
public static Matrix33 ComputeTransform(IList <Point> fromPoints, IList <ILocation> toAnchors)
{
if (toAnchors == null || fromPoints == null)
{
return(null);
}
var anchorMatrix = new Matrix33(toAnchors);
var pointMatrix = new Matrix33(fromPoints);
return(pointMatrix.Inverse().Product(anchorMatrix));
}
/// <summary>
/// Computes the product of two matrices.
/// </summary>
/// <param name="n">
/// The matrix to multiply against - this x n.
/// </param>
/// <returns>
/// The product of the two matrices.
/// </returns>
public Matrix33 Product(Matrix33 n)
{
// Don't bother with the _m entries since they're not being used.
// Better not concatenate anything though.
var p = new Matrix33
{
M11 = (this.M11 * n.M11) + (this.M12 * n.M21) + (this.m13 * n.M31),
M12 = (this.M11 * n.M12) + (this.M12 * n.M22) + (this.m13 * n.M32),
M21 = (this.M21 * n.M11) + (this.M22 * n.M21) + (this.m23 * n.M31),
M22 = (this.M21 * n.M12) + (this.M22 * n.M22) + (this.m23 * n.M32),
M31 = (this.M31 * n.M11) + (this.M32 * n.M21) + (this.m33 * n.M31),
M32 = (this.M31 * n.M12) + (this.M32 * n.M22) + (this.m33 * n.M32)
};
return(p);
}
/// <summary>
/// Returns the inverse of the matrix.
/// </summary>
/// <returns>
/// The inverse of the matrix.
/// </returns>
public Matrix33 Inverse()
{
double d = this.Determinant();
var inv = new Matrix33
{
M11 = (this.M22 - this.M32) / d,
M21 = (this.M31 - this.M21) / d,
M31 = ((this.M21 * this.M32) - (this.M22 * this.M31)) / d,
M12 = (this.M32 - this.M12) / d,
M22 = (this.M11 - this.M31) / d,
M32 = ((this.M31 * this.M12) - (this.M11 * this.M32)) / d,
m13 = (this.M12 - this.M22) / d,
m23 = (this.M21 - this.M11) / d,
m33 = ((this.M11 * this.M22) - (this.M12 * this.M21)) / d
};
return(inv);
}
