| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.geometry.euclidean.twod; |
| |
| import java.io.Serializable; |
| |
| import org.apache.commons.geometry.core.internal.DoubleFunction2N; |
| import org.apache.commons.geometry.euclidean.AffineTransformMatrix; |
| import org.apache.commons.geometry.euclidean.exception.NonInvertibleTransformException; |
| import org.apache.commons.geometry.euclidean.internal.Matrices; |
| import org.apache.commons.geometry.euclidean.internal.Vectors; |
| import org.apache.commons.geometry.euclidean.oned.Vector1D; |
| import org.apache.commons.numbers.arrays.LinearCombination; |
| import org.apache.commons.numbers.core.Precision; |
| |
| /** Class using a matrix to represent affine transformations in 2 dimensional Euclidean space. |
| * |
| * <p>Instances of this class use a 3x3 matrix for all transform operations. |
| * The last row of this matrix is always set to the values <code>[0 0 1]</code> and so |
| * is not stored. Hence, the methods in this class that accept or return arrays always |
| * use arrays containing 6 elements, instead of 9. |
| * </p> |
| */ |
| public final class AffineTransformMatrix2D implements AffineTransformMatrix<Vector2D, Vector1D>, Serializable { |
| |
| /** Serializable version identifier */ |
| private static final long serialVersionUID = 20181005L; |
| |
| /** The number of internal matrix elements */ |
| private static final int NUM_ELEMENTS = 6; |
| |
| /** String used to start the transform matrix string representation */ |
| private static final String MATRIX_START = "[ "; |
| |
| /** String used to end the transform matrix string representation */ |
| private static final String MATRIX_END = " ]"; |
| |
| /** String used to separate elements in the matrix string representation */ |
| private static final String ELEMENT_SEPARATOR = ", "; |
| |
| /** String used to separate rows in the matrix string representation */ |
| private static final String ROW_SEPARATOR = "; "; |
| |
| /** Shared transform set to the identity matrix. */ |
| private static final AffineTransformMatrix2D IDENTITY_INSTANCE = new AffineTransformMatrix2D( |
| 1, 0, 0, |
| 0, 1, 0 |
| ); |
| |
| /** Transform matrix entry <code>m<sub>0,0</sub></code> */ |
| private final double m00; |
| /** Transform matrix entry <code>m<sub>0,1</sub></code> */ |
| private final double m01; |
| /** Transform matrix entry <code>m<sub>0,2</sub></code> */ |
| private final double m02; |
| |
| /** Transform matrix entry <code>m<sub>1,0</sub></code> */ |
| private final double m10; |
| /** Transform matrix entry <code>m<sub>1,1</sub></code> */ |
| private final double m11; |
| /** Transform matrix entry <code>m<sub>1,2</sub></code> */ |
| private final double m12; |
| |
| /** |
| * Simple constructor; sets all internal matrix elements. |
| * @param m00 matrix entry <code>m<sub>0,0</sub></code> |
| * @param m01 matrix entry <code>m<sub>0,1</sub></code> |
| * @param m02 matrix entry <code>m<sub>0,2</sub></code> |
| * @param m10 matrix entry <code>m<sub>1,0</sub></code> |
| * @param m11 matrix entry <code>m<sub>1,1</sub></code> |
| * @param m12 matrix entry <code>m<sub>1,2</sub></code> |
| */ |
| private AffineTransformMatrix2D( |
| final double m00, final double m01, final double m02, |
| final double m10, final double m11, final double m12) { |
| |
| this.m00 = m00; |
| this.m01 = m01; |
| this.m02 = m02; |
| |
| this.m10 = m10; |
| this.m11 = m11; |
| this.m12 = m12; |
| } |
| |
| /** Return a 6 element array containing the variable elements from the |
| * internal transformation matrix. The elements are in row-major order. |
| * The array indices map to the internal matrix as follows: |
| * <pre> |
| * [ |
| * arr[0], arr[1], arr[2], |
| * arr[3], arr[4], arr[5], |
| * 0 0 1 |
| * ] |
| * </pre> |
| * @return 6 element array containing the variable elements from the |
| * internal transformation matrix |
| */ |
| public double[] toArray() { |
| return new double[] { |
| m00, m01, m02, |
| m10, m11, m12 |
| }; |
| } |
| |
| /** Apply this transform to the given point, returning the result as a new instance. |
| * |
| * <p>The transformed point is computed by creating a 3-element column vector from the |
| * coordinates in the input and setting the last element to 1. This is then multiplied with the |
| * 3x3 transform matrix to produce the transformed point. The {@code 1} in the last position |
| * is ignored. |
| * <pre> |
| * [ m00 m01 m02 ] [ x ] [ x'] |
| * [ m10 m11 m12 ] * [ y ] = [ y'] |
| * [ 0 0 1 ] [ 1 ] [ 1 ] |
| * </pre> |
| */ |
| @Override |
| public Vector2D apply(final Vector2D pt) { |
| final double x = pt.getX(); |
| final double y = pt.getY(); |
| |
| final double resultX = LinearCombination.value(m00, x, m01, y) + m02; |
| final double resultY = LinearCombination.value(m10, x, m11, y) + m12; |
| |
| return Vector2D.of(resultX, resultY); |
| } |
| |
| /** {@inheritDoc} |
| * |
| * <p>The transformed vector is computed by creating a 3-element column vector from the |
| * coordinates in the input and setting the last element to 0. This is then multiplied with the |
| * 3x3 transform matrix to produce the transformed vector. The {@code 0} in the last position |
| * is ignored. |
| * <pre> |
| * [ m00 m01 m02 ] [ x ] [ x'] |
| * [ m10 m11 m12 ] * [ y ] = [ y'] |
| * [ 0 0 1 ] [ 0 ] [ 0 ] |
| * </pre> |
| * |
| * @see #applyDirection(Vector2D) |
| */ |
| @Override |
| public Vector2D applyVector(final Vector2D vec) { |
| return applyVector(vec, Vector2D::of); |
| } |
| |
| /** {@inheritDoc} |
| * @see #applyVector(Vector2D) |
| */ |
| @Override |
| public Vector2D applyDirection(final Vector2D vec) { |
| return applyVector(vec, Vector2D::normalize); |
| } |
| |
| /** Apply a translation to the current instance, returning the result as a new transform. |
| * @param translation vector containing the translation values for each axis |
| * @return a new transform containing the result of applying a translation to |
| * the current instance |
| */ |
| public AffineTransformMatrix2D translate(final Vector2D translation) { |
| return translate(translation.getX(), translation.getY()); |
| } |
| |
| /** Apply a translation to the current instance, returning the result as a new transform. |
| * @param x translation in the x direction |
| * @param y translation in the y direction |
| * @return a new transform containing the result of applying a translation to |
| * the current instance |
| */ |
| public AffineTransformMatrix2D translate(final double x, final double y) { |
| return new AffineTransformMatrix2D( |
| m00, m01, m02 + x, |
| m10, m11, m12 + y |
| ); |
| } |
| |
| /** Apply a scale operation to the current instance, returning the result as a new transform. |
| * @param factor the scale factor to apply to all axes |
| * @return a new transform containing the result of applying a scale operation to |
| * the current instance |
| */ |
| public AffineTransformMatrix2D scale(final double factor) { |
| return scale(factor, factor); |
| } |
| |
| /** Apply a scale operation to the current instance, returning the result as a new transform. |
| * @param scaleFactors vector containing scale factors for each axis |
| * @return a new transform containing the result of applying a scale operation to |
| * the current instance |
| */ |
| public AffineTransformMatrix2D scale(final Vector2D scaleFactors) { |
| return scale(scaleFactors.getX(), scaleFactors.getY()); |
| } |
| |
| /** Apply a scale operation to the current instance, returning the result as a new transform. |
| * @param x scale factor for the x axis |
| * @param y scale factor for the y axis |
| * @return a new transform containing the result of applying a scale operation to |
| * the current instance |
| */ |
| public AffineTransformMatrix2D scale(final double x, final double y) { |
| return new AffineTransformMatrix2D( |
| m00 * x, m01 * x, m02 * x, |
| m10 * y, m11 * y, m12 * y |
| ); |
| } |
| |
| /** Apply a <em>counterclockwise</em> rotation to the current instance, returning the result as a |
| * new transform. |
| * @param angle the angle of counterclockwise rotation in radians |
| * @return a new transform containing the result of applying a rotation to the |
| * current instance |
| */ |
| public AffineTransformMatrix2D rotate(final double angle) { |
| return multiply(createRotation(angle), this); |
| } |
| |
| /** Apply a <em>counterclockwise</em> rotation about the given center point to the current instance, |
| * returning the result as a new transform. This is accomplished by translating the center to the origin, |
| * applying the rotation, and then translating back. |
| * @param center the center of rotation |
| * @param angle the angle of counterclockwise rotation in radians |
| * @return a new transform containing the result of applying a rotation about the given |
| * center point to the current instance |
| */ |
| public AffineTransformMatrix2D rotate(final Vector2D center, final double angle) { |
| return multiply(createRotation(center, angle), this); |
| } |
| |
| /** Get a new transform created by multiplying this instance by the argument. |
| * This is equivalent to the expression {@code A * M} where {@code A} is the |
| * current transform matrix and {@code M} is the given transform matrix. In |
| * terms of transformations, applying the returned matrix is equivalent to |
| * applying {@code M} and <em>then</em> applying {@code A}. In other words, |
| * the rightmost transform is applied first. |
| * |
| * @param m the transform to multiply with |
| * @return the result of multiplying the current instance by the given |
| * transform matrix |
| */ |
| public AffineTransformMatrix2D multiply(final AffineTransformMatrix2D m) { |
| return multiply(this, m); |
| } |
| |
| /** Get a new transform created by multiplying the argument by this instance. |
| * This is equivalent to the expression {@code M * A} where {@code A} is the |
| * current transform matrix and {@code M} is the given transform matrix. In |
| * terms of transformations, applying the returned matrix is equivalent to |
| * applying {@code A} and <em>then</em> applying {@code M}. In other words, |
| * the rightmost transform is applied first. |
| * |
| * @param m the transform to multiply with |
| * @return the result of multiplying the given transform matrix by the current |
| * instance |
| */ |
| public AffineTransformMatrix2D premultiply(final AffineTransformMatrix2D m) { |
| return multiply(m, this); |
| } |
| |
| /** Get a new transform representing the inverse of the current instance. |
| * @return inverse transform |
| * @throws NonInvertibleTransformException if the transform matrix cannot be inverted |
| */ |
| public AffineTransformMatrix2D inverse() throws NonInvertibleTransformException { |
| |
| // Our full matrix is 3x3 but we can significantly reduce the amount of computations |
| // needed here since we know that our last row is [0 0 1]. |
| |
| // compute the determinant of the matrix |
| final double det = Matrices.determinant( |
| m00, m01, |
| m10, m11 |
| ); |
| |
| if (!Vectors.isRealNonZero(det)) { |
| throw new NonInvertibleTransformException("Transform is not invertible; matrix determinant is " + det); |
| } |
| |
| // validate the remaining matrix elements that were not part of the determinant |
| validateElementForInverse(m02); |
| validateElementForInverse(m12); |
| |
| // compute the necessary elements of the cofactor matrix |
| // (we need all but the last column) |
| |
| final double invDet = 1.0 / det; |
| |
| final double c00 = invDet * m11; |
| final double c01 = - invDet * m10; |
| |
| final double c10 = - invDet * m01; |
| final double c11 = invDet * m00; |
| |
| final double c20 = invDet * Matrices.determinant(m01, m02, m11, m12); |
| final double c21 = - invDet * Matrices.determinant(m00, m02, m10, m12); |
| |
| return new AffineTransformMatrix2D( |
| c00, c10, c20, |
| c01, c11, c21 |
| ); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public int hashCode() { |
| final int prime = 31; |
| int result = 1; |
| |
| result = (result * prime) + (Double.hashCode(m00) - Double.hashCode(m01) + Double.hashCode(m02)); |
| result = (result * prime) + (Double.hashCode(m10) - Double.hashCode(m11) + Double.hashCode(m12)); |
| |
| return result; |
| } |
| |
| /** |
| * Return true if the given object is an instance of {@link AffineTransformMatrix2D} |
| * and all matrix element values are exactly equal. |
| * @param obj object to test for equality with the current instance |
| * @return true if all transform matrix elements are exactly equal; otherwise false |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (this == obj) { |
| return true; |
| } |
| if (!(obj instanceof AffineTransformMatrix2D)) { |
| return false; |
| } |
| |
| final AffineTransformMatrix2D other = (AffineTransformMatrix2D) obj; |
| |
| return Precision.equals(this.m00, other.m00) && |
| Precision.equals(this.m01, other.m01) && |
| Precision.equals(this.m02, other.m02) && |
| |
| Precision.equals(this.m10, other.m10) && |
| Precision.equals(this.m11, other.m11) && |
| Precision.equals(this.m12, other.m12); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public String toString() { |
| final StringBuilder sb = new StringBuilder(); |
| |
| sb.append(MATRIX_START) |
| |
| .append(m00) |
| .append(ELEMENT_SEPARATOR) |
| .append(m01) |
| .append(ELEMENT_SEPARATOR) |
| .append(m02) |
| .append(ROW_SEPARATOR) |
| |
| .append(m10) |
| .append(ELEMENT_SEPARATOR) |
| .append(m11) |
| .append(ELEMENT_SEPARATOR) |
| .append(m12) |
| |
| .append(MATRIX_END); |
| |
| return sb.toString(); |
| } |
| |
| /** Multiplies the given vector by the 2x2 linear transformation matrix contained in the |
| * upper-right corner of the affine transformation matrix. This applies all transformation |
| * operations except for translations. The computed coordinates are passed to the given |
| * factory function. |
| * @param <T> factory output type |
| * @param vec the vector to transform |
| * @param factory the factory instance that will be passed the transformed coordinates |
| * @return the factory return value |
| */ |
| private <T> T applyVector(final Vector2D vec, final DoubleFunction2N<T> factory) { |
| final double x = vec.getX(); |
| final double y = vec.getY(); |
| |
| final double resultX = LinearCombination.value(m00, x, m01, y); |
| final double resultY = LinearCombination.value(m10, x, m11, y); |
| |
| return factory.apply(resultX, resultY); |
| } |
| |
| /** Get a new transform with the given matrix elements. The array must contain 6 elements. |
| * @param arr 6-element array containing values for the variable entries in the |
| * transform matrix |
| * @return a new transform initialized with the given matrix values |
| * @throws IllegalArgumentException if the array does not have 6 elements |
| */ |
| public static AffineTransformMatrix2D of(final double ... arr) { |
| if (arr.length != NUM_ELEMENTS) { |
| throw new IllegalArgumentException("Dimension mismatch: " + arr.length + " != " + NUM_ELEMENTS); |
| } |
| |
| return new AffineTransformMatrix2D( |
| arr[0], arr[1], arr[2], |
| arr[3], arr[4], arr[5] |
| ); |
| } |
| |
| /** Get a new transform create from the given column vectors. The returned transform |
| * does not include any translation component. |
| * @param u first column vector; this corresponds to the first basis vector |
| * in the coordinate frame |
| * @param v second column vector; this corresponds to the second basis vector |
| * in the coordinate frame |
| * @return a new transform with the given column vectors |
| */ |
| public static AffineTransformMatrix2D fromColumnVectors(final Vector2D u, final Vector2D v) { |
| return fromColumnVectors(u, v, Vector2D.ZERO); |
| } |
| |
| /** Get a new transform created from the given column vectors. |
| * @param u first column vector; this corresponds to the first basis vector |
| * in the coordinate frame |
| * @param v second column vector; this corresponds to the second basis vector |
| * in the coordinate frame |
| * @param t third column vector; this corresponds to the translation of the transform |
| * @return a new transform with the given column vectors |
| */ |
| public static AffineTransformMatrix2D fromColumnVectors(final Vector2D u, final Vector2D v, final Vector2D t) { |
| return new AffineTransformMatrix2D( |
| u.getX(), v.getX(), t.getX(), |
| u.getY(), v.getY(), t.getY() |
| ); |
| } |
| |
| /** Get the transform representing the identity matrix. This transform does not |
| * modify point or vector values when applied. |
| * @return transform representing the identity matrix |
| */ |
| public static AffineTransformMatrix2D identity() { |
| return IDENTITY_INSTANCE; |
| } |
| |
| /** Create a transform representing the given translation. |
| * @param translation vector containing translation values for each axis |
| * @return a new transform representing the given translation |
| */ |
| public static AffineTransformMatrix2D createTranslation(final Vector2D translation) { |
| return createTranslation(translation.getX(), translation.getY()); |
| } |
| |
| /** Create a transform representing the given translation. |
| * @param x translation in the x direction |
| * @param y translation in the y direction |
| * @return a new transform representing the given translation |
| */ |
| public static AffineTransformMatrix2D createTranslation(final double x, final double y) { |
| return new AffineTransformMatrix2D( |
| 1, 0, x, |
| 0, 1, y |
| ); |
| } |
| |
| /** Create a transform representing a scale operation with the given scale factor applied to all axes. |
| * @param factor scale factor to apply to all axes |
| * @return a new transform representing a uniform scaling in all axes |
| */ |
| public static AffineTransformMatrix2D createScale(final double factor) { |
| return createScale(factor, factor); |
| } |
| |
| /** Create a transform representing a scale operation. |
| * @param factors vector containing scale factors for each axis |
| * @return a new transform representing a scale operation |
| */ |
| public static AffineTransformMatrix2D createScale(final Vector2D factors) { |
| return createScale(factors.getX(), factors.getY()); |
| } |
| |
| /** Create a transform representing a scale operation. |
| * @param x scale factor for the x axis |
| * @param y scale factor for the y axis |
| * @return a new transform representing a scale operation |
| */ |
| public static AffineTransformMatrix2D createScale(final double x, final double y) { |
| return new AffineTransformMatrix2D( |
| x, 0, 0, |
| 0, y, 0 |
| ); |
| } |
| |
| /** Create a transform representing a <em>counterclockwise</em> rotation of {@code angle} |
| * radians around the origin. |
| * @param angle the angle of rotation in radians |
| * @return a new transform representing the rotation |
| */ |
| public static AffineTransformMatrix2D createRotation(final double angle) { |
| final double sin = Math.sin(angle); |
| final double cos = Math.cos(angle); |
| |
| return new AffineTransformMatrix2D( |
| cos, -sin, 0, |
| sin, cos, 0 |
| ); |
| } |
| |
| /** Create a transform representing a <em>counterclockwise</em> rotation of {@code angle} |
| * radians around the given center point. This is accomplished by translating the center point |
| * to the origin, applying the rotation, and then translating back. |
| * @param center the center of rotation |
| * @param angle the angle of rotation in radians |
| * @return a new transform representing the rotation about the given center |
| */ |
| public static AffineTransformMatrix2D createRotation(final Vector2D center, final double angle) { |
| final double x = center.getX(); |
| final double y = center.getY(); |
| |
| final double sin = Math.sin(angle); |
| final double cos = Math.cos(angle); |
| |
| return new AffineTransformMatrix2D( |
| cos, -sin, (-x * cos) + (y * sin) + x, |
| sin, cos, (-x * sin) - (y * cos) + y |
| ); |
| } |
| |
| /** Multiply two transform matrices together. |
| * @param a first transform |
| * @param b second transform |
| * @return the transform computed as {@code a x b} |
| */ |
| private static AffineTransformMatrix2D multiply(final AffineTransformMatrix2D a, final AffineTransformMatrix2D b) { |
| |
| final double c00 = LinearCombination.value(a.m00, b.m00, a.m01, b.m10); |
| final double c01 = LinearCombination.value(a.m00, b.m01, a.m01, b.m11); |
| final double c02 = LinearCombination.value(a.m00, b.m02, a.m01, b.m12) + a.m02; |
| |
| final double c10 = LinearCombination.value(a.m10, b.m00, a.m11, b.m10); |
| final double c11 = LinearCombination.value(a.m10, b.m01, a.m11, b.m11); |
| final double c12 = LinearCombination.value(a.m10, b.m02, a.m11, b.m12) + a.m12; |
| |
| return new AffineTransformMatrix2D( |
| c00, c01, c02, |
| c10, c11, c12 |
| ); |
| } |
| |
| /** Checks that the given matrix element is valid for use in calculation of |
| * a matrix inverse. Throws a {@link NonInvertibleTransformException} if not. |
| * @param element matrix entry to check |
| * @throws NonInvertibleTransformException if the element is not valid for use |
| * in calculating a matrix inverse, ie if it is NaN or infinite. |
| */ |
| private static void validateElementForInverse(final double element) throws NonInvertibleTransformException { |
| if (!Double.isFinite(element)) { |
| throw new NonInvertibleTransformException("Transform is not invertible; invalid matrix element: " + element); |
| } |
| } |
| } |