AbstractAffineTransformMatrix.java
- /*
- * 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;
- /** Base class for affine transform matrices in Euclidean space.
- *
- * @param <V> Vector/point implementation type defining the space.
- * @param <M> Matrix transform implementation type.
- */
- public abstract class AbstractAffineTransformMatrix<
- V extends EuclideanVector<V>,
- M extends AbstractAffineTransformMatrix<V, M>>
- implements EuclideanTransform<V> {
- /** Apply this transform to the given vector, ignoring translations and normalizing the
- * result. This is equivalent to {@code transform.applyVector(vec).normalize()} but without
- * the intermediate vector instance.
- *
- * @param vec the vector to transform
- * @return the new, transformed unit vector
- * @throws IllegalArgumentException if the transformed vector coordinates cannot be normalized
- * @see #applyVector(EuclideanVector)
- */
- public abstract V applyDirection(V vec);
- /** Get the determinant of the matrix.
- * @return the determinant of the matrix
- */
- public abstract double determinant();
- /** {@inheritDoc}
- * @throws IllegalStateException if the matrix cannot be inverted
- */
- @Override
- public abstract M inverse();
- /** Return a matrix containing only the linear portion of this transform.
- * The returned instance contains the same matrix elements as this instance
- * but with the translation component set to zero.
- * @return a matrix containing only the linear portion of this transform
- */
- public abstract M linear();
- /** Return a matrix containing the transpose of the linear portion of this transform.
- * The returned instance is linear, meaning it has a translation component of zero.
- * @return a matrix containing the transpose of the linear portion of this transform
- */
- public abstract M linearTranspose();
- /** Return a transform suitable for transforming normals. The returned matrix is
- * the inverse transpose of the linear portion of this instance, i.e.
- * <code>N = (L<sup>-1</sup>)<sup>T</sup></code>, where <code>L</code> is the linear portion
- * of this instance and <code>N</code> is the returned matrix. Note that normals
- * transformed with the returned matrix may be scaled during transformation and require
- * normalization.
- * @return a transform suitable for transforming normals
- * @throws IllegalStateException if the matrix cannot be inverted
- * @see <a href="https://en.wikipedia.org/wiki/Normal_(geometry)#Transforming_normals">Transforming normals</a>
- */
- public M normalTransform() {
- return inverse().linearTranspose();
- }
- /** {@inheritDoc}
- *
- * <p>This method returns true if the determinant of the matrix is positive.</p>
- */
- @Override
- public boolean preservesOrientation() {
- return determinant() > 0.0;
- }
- }