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Java example source code file (AbstractSubHyperplane.java)

This example Java source code file (AbstractSubHyperplane.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractsubhyperplane, boundaryattribute, bsptree, deprecated, hashmap, map, nodesset, region, side, space, splitsubhyperplane, suppresswarnings, transform, util

The AbstractSubHyperplane.java Java example source code

/*
 * 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.math3.geometry.partitioning;

import java.util.HashMap;
import java.util.Map;

import org.apache.commons.math3.geometry.Space;

/** This class implements the dimension-independent parts of {@link SubHyperplane}.

 * <p>sub-hyperplanes are obtained when parts of an {@link
 * Hyperplane hyperplane} are chopped off by other hyperplanes that
 * intersect it. The remaining part is a convex region. Such objects
 * appear in {@link BSPTree BSP trees} as the intersection of a cut
 * hyperplane with the convex region which it splits, the chopping
 * hyperplanes are the cut hyperplanes closer to the tree root.</p>

 * @param <S> Type of the embedding space.
 * @param <T> Type of the embedded sub-space.

 * @since 3.0
 */
public abstract class AbstractSubHyperplane<S extends Space, T extends Space>
    implements SubHyperplane<S> {

    /** Underlying hyperplane. */
    private final Hyperplane<S> hyperplane;

    /** Remaining region of the hyperplane. */
    private final Region<T> remainingRegion;

    /** Build a sub-hyperplane from an hyperplane and a region.
     * @param hyperplane underlying hyperplane
     * @param remainingRegion remaining region of the hyperplane
     */
    protected AbstractSubHyperplane(final Hyperplane<S> hyperplane,
                                    final Region<T> remainingRegion) {
        this.hyperplane      = hyperplane;
        this.remainingRegion = remainingRegion;
    }

    /** Build a sub-hyperplane from an hyperplane and a region.
     * @param hyper underlying hyperplane
     * @param remaining remaining region of the hyperplane
     * @return a new sub-hyperplane
     */
    protected abstract AbstractSubHyperplane<S, T> buildNew(final Hyperplane hyper,
                                                            final Region<T> remaining);

    /** {@inheritDoc} */
    public AbstractSubHyperplane<S, T> copySelf() {
        return buildNew(hyperplane.copySelf(), remainingRegion);
    }

    /** Get the underlying hyperplane.
     * @return underlying hyperplane
     */
    public Hyperplane<S> getHyperplane() {
        return hyperplane;
    }

    /** Get the remaining region of the hyperplane.
     * <p>The returned region is expressed in the canonical hyperplane
     * frame and has the hyperplane dimension. For example a chopped
     * hyperplane in the 3D euclidean is a 2D plane and the
     * corresponding region is a convex 2D polygon.</p>
     * @return remaining region of the hyperplane
     */
    public Region<T> getRemainingRegion() {
        return remainingRegion;
    }

    /** {@inheritDoc} */
    public double getSize() {
        return remainingRegion.getSize();
    }

    /** {@inheritDoc} */
    public AbstractSubHyperplane<S, T> reunite(final SubHyperplane other) {
        @SuppressWarnings("unchecked")
        AbstractSubHyperplane<S, T> o = (AbstractSubHyperplane) other;
        return buildNew(hyperplane,
                        new RegionFactory<T>().union(remainingRegion, o.remainingRegion));
    }

    /** Apply a transform to the instance.
     * <p>The instance must be a (D-1)-dimension sub-hyperplane with
     * respect to the transform <em>not a (D-2)-dimension
     * sub-hyperplane the transform knows how to transform by
     * itself. The transform will consist in transforming first the
     * hyperplane and then the all region using the various methods
     * provided by the transform.</p>
     * @param transform D-dimension transform to apply
     * @return the transformed instance
     */
    public AbstractSubHyperplane<S, T> applyTransform(final Transform transform) {
        final Hyperplane<S> tHyperplane = transform.apply(hyperplane);

        // transform the tree, except for boundary attribute splitters
        final Map<BSPTree> map = new HashMap, BSPTree>();
        final BSPTree<T> tTree =
            recurseTransform(remainingRegion.getTree(false), tHyperplane, transform, map);

        // set up the boundary attributes splitters
        for (final Map.Entry<BSPTree> entry : map.entrySet()) {
            if (entry.getKey().getCut() != null) {
                @SuppressWarnings("unchecked")
                BoundaryAttribute<T> original = (BoundaryAttribute) entry.getKey().getAttribute();
                if (original != null) {
                    @SuppressWarnings("unchecked")
                    BoundaryAttribute<T> transformed = (BoundaryAttribute) entry.getValue().getAttribute();
                    for (final BSPTree<T> splitter : original.getSplitters()) {
                        transformed.getSplitters().add(map.get(splitter));
                    }
                }
            }
        }

        return buildNew(tHyperplane, remainingRegion.buildNew(tTree));

    }

    /** Recursively transform a BSP-tree from a sub-hyperplane.
     * @param node current BSP tree node
     * @param transformed image of the instance hyperplane by the transform
     * @param transform transform to apply
     * @param map transformed nodes map
     * @return a new tree
     */
    private BSPTree<T> recurseTransform(final BSPTree node,
                                        final Hyperplane<S> transformed,
                                        final Transform<S, T> transform,
                                        final Map<BSPTree> map) {

        final BSPTree<T> transformedNode;
        if (node.getCut() == null) {
            transformedNode = new BSPTree<T>(node.getAttribute());
        } else {

            @SuppressWarnings("unchecked")
            BoundaryAttribute<T> attribute = (BoundaryAttribute) node.getAttribute();
            if (attribute != null) {
                final SubHyperplane<T> tPO = (attribute.getPlusOutside() == null) ?
                    null : transform.apply(attribute.getPlusOutside(), hyperplane, transformed);
                final SubHyperplane<T> tPI = (attribute.getPlusInside() == null) ?
                    null : transform.apply(attribute.getPlusInside(), hyperplane, transformed);
                // we start with an empty list of splitters, it will be filled in out of recursion
                attribute = new BoundaryAttribute<T>(tPO, tPI, new NodesSet());
            }

            transformedNode = new BSPTree<T>(transform.apply(node.getCut(), hyperplane, transformed),
                    recurseTransform(node.getPlus(),  transformed, transform, map),
                    recurseTransform(node.getMinus(), transformed, transform, map),
                    attribute);
        }

        map.put(node, transformedNode);
        return transformedNode;

    }

    /** {@inheritDoc} */
    @Deprecated
    public Side side(Hyperplane<S> hyper) {
        return split(hyper).getSide();
    }

    /** {@inheritDoc} */
    public abstract SplitSubHyperplane<S> split(Hyperplane hyper);

    /** {@inheritDoc} */
    public boolean isEmpty() {
        return remainingRegion.isEmpty();
    }

}

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