/**
* Constructs a 3D affine transformation using the given matrix.
*
* <p>Affine transformations can be applied to 3D or homogeneous 3D coordinates. A 3 by 3 matrix
* sets the rotation and shear portion of the transformation. A 4 by 4 matrix sets rotation,
* shear, and translation. A null matrix sets the transformation to the identity transformation.
*
* @param mat double[][]
*/
public Affine3DMatrix(double[][] matrix) {
if (matrix == null) { // identity matrix
this.matrix[0][0] = this.matrix[1][1] = this.matrix[2][2] = this.matrix[3][3] = 1;
return;
}
for (int i = 0; i < matrix.length; i++) { // loop over the rows
System.arraycopy(matrix[i], 0, this.matrix, 0, matrix[i].length);
}
}
/**
* Transforms the given point.
*
* @param point the coordinates to be transformed
*/
public double[] direct(double[] point) {
int n = point.length;
double[] tempPoint = new double[n];
System.arraycopy(point, 0, tempPoint, 0, n);
for (int i = 0; i < n; i++) {
point[i] = 0;
for (int j = 0; j < n; j++) {
point[i] += matrix[i][j] * tempPoint[j];
}
}
return point;
}
/**
* Transforms the given point using the inverse transformation (if it exists).
*
* <p>If the transformation is not invertible, then a call to this method must throw a
* UnsupportedOperationException exception.
*
* @param point the coordinates to be transformed
*/
public double[] inverse(double[] point) throws UnsupportedOperationException {
if (!inverted) {
calcInverse(); // computes inverse using LU decompostion
}
if (inverse == null) { // inverse does not exist
throw new UnsupportedOperationException("inverse matrix does not exist.");
}
int n = point.length;
double[] pt = new double[n];
System.arraycopy(point, 0, pt, 0, n);
for (int i = 0; i < n; i++) {
point[i] = 0;
for (int j = 0; j < n; j++) {
point[i] += inverse[i][j] * pt[j];
}
}
return point;
}
