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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.geometry.examples.tutorials.bsp;
    18
    19  import java.io.File;
    20  import java.util.Arrays;
    21
    22  import org.apache.commons.geometry.core.precision.DoublePrecisionContext;
    23  import org.apache.commons.geometry.core.precision.EpsilonDoublePrecisionContext;
    24  import org.apache.commons.geometry.euclidean.twod.Bounds2D;
    25  import org.apache.commons.geometry.euclidean.twod.RegionBSPTree2D;
    26  import org.apache.commons.geometry.euclidean.twod.Vector2D;
    27  import org.apache.commons.geometry.euclidean.twod.path.LinePath;
    28
    29  /** Class containing tutorial code for computing the union of two trees.
    30   */
    31  public final class BSPTreeUnion {
    32
    33      /** No instantiation. */
    34      private BSPTreeUnion() {}
    35
    36      /** Tutorial code entry point.
    37       * @param args command arguments; if given, the first argument is used as the location of
    38       *      output folder
    39       */
    40      public static void main(String[] args) {
    41          File outputFolder = new File(args.length > 0 ? args[0] : ".");
    42          BSPTreeSVGWriter svgWriter = new BSPTreeSVGWriter(Bounds2D.from(Vector2D.of(-8, -8), Vector2D.of(8, 8)));
    43
    44          DoublePrecisionContext precision = new EpsilonDoublePrecisionContext(1e-6);
    45
    46          RegionBSPTree2D a = LinePath.fromVertexLoop(Arrays.asList(
    47                      Vector2D.of(2, 0),
    48                      Vector2D.of(-4, 3),
    49                      Vector2D.of(-4, -3)
    50                  ), precision).toTree();
    51
    52          RegionBSPTree2D b = LinePath.fromVertexLoop(Arrays.asList(
    53                  Vector2D.of(-2, 0),
    54                  Vector2D.of(4, -3),
    55                  Vector2D.of(4, 3)
    56              ), precision).toTree();
    57
    58          RegionBSPTree2D result = RegionBSPTree2D.empty();
    59
    60          result.union(a, b);
    61
    62          svgWriter.write(result, new File(outputFolder, "union.svg"));
    63      }
    64  }