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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.partitioning.bsp.RegionCutRule;
    23  import org.apache.commons.geometry.core.precision.DoublePrecisionContext;
    24  import org.apache.commons.geometry.core.precision.EpsilonDoublePrecisionContext;
    25  import org.apache.commons.geometry.euclidean.twod.Bounds2D;
    26  import org.apache.commons.geometry.euclidean.twod.Lines;
    27  import org.apache.commons.geometry.euclidean.twod.RegionBSPTree2D;
    28  import org.apache.commons.geometry.euclidean.twod.Vector2D;
    29  import org.apache.commons.geometry.euclidean.twod.path.LinePath;
    30
    31  /** Class containing tutorial code for constructing a balanced tree using a single
    32   * structural cut.
    33   */
    34  public final class HexagonStructuralCut {
    35
    36      /** No instantiation. */
    37      private HexagonStructuralCut() {}
    38
    39      /** Tutorial code entry point.
    40       * @param args command arguments; if given, the first argument is used as the location of
    41       *      output folder
    42       */
    43      public static void main(String[] args) {
    44          File outputFolder = new File(args.length > 0 ? args[0] : ".");
    45          BSPTreeSVGWriter svgWriter = new BSPTreeSVGWriter(Bounds2D.from(Vector2D.of(-8, -8), Vector2D.of(8, 8)));
    46
    47          DoublePrecisionContext precision = new EpsilonDoublePrecisionContext(1e-6);
    48
    49          RegionBSPTree2D tree = RegionBSPTree2D.empty();
    50
    51          tree.insert(Lines.fromPointAndDirection(Vector2D.ZERO, Vector2D.Unit.PLUS_X, precision).span(),
    52                  RegionCutRule.INHERIT);
    53
    54          svgWriter.write(tree, new File(outputFolder, "hex-struct-0.svg"));
    55
    56          LinePath path = LinePath.fromVertexLoop(Arrays.asList(
    57                      Vector2D.of(-4, 0),
    58                      Vector2D.of(-2, -3),
    59                      Vector2D.of(2, -3),
    60                      Vector2D.of(4, 0),
    61                      Vector2D.of(2, 3),
    62                      Vector2D.of(-2, 3)
    63                  ), precision);
    64          tree.insert(path);
    65
    66          svgWriter.write(tree, new File(outputFolder, "hex-struct-1.svg"));
    67      }
    68  }