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17 package org.apache.commons.geometry.examples.tutorials.bsp;
18
19 import java.io.File;
20 import java.util.HashMap;
21 import java.util.Map;
22
23 import org.apache.commons.geometry.euclidean.twod.Bounds2D;
24 import org.apache.commons.geometry.euclidean.twod.Line;
25 import org.apache.commons.geometry.euclidean.twod.Lines;
26 import org.apache.commons.geometry.euclidean.twod.RegionBSPTree2D;
27 import org.apache.commons.geometry.euclidean.twod.RegionBSPTree2D.RegionNode2D;
28 import org.apache.commons.geometry.euclidean.twod.Vector2D;
29 import org.apache.commons.numbers.core.Precision;
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33
34 public final class BottomUpBSPTreeConstruction {
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36
37 private static final String OUTPUT_FILE_FORMAT = "bu-cut-%d.svg";
38
39
40 private BottomUpBSPTreeConstruction() {}
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45
46 public static void main(final String[] args) {
47 final File outputFolder = new File(args.length > 0 ? args[0] : ".");
48 final BSPTreeSVGWriter svgWriter = new BSPTreeSVGWriter(Bounds2D.from(Vector2D.of(-8, -8), Vector2D.of(8, 8)));
49
50 final Map<RegionNode2D, String> nodeNames = new HashMap<>();
51 int cutCount = -1;
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54 final Precision.DoubleEquivalence precision = Precision.doubleEquivalenceOfEpsilon(1e-6);
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56
57 final RegionBSPTree2D tree = RegionBSPTree2D.empty();
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59 final Line rootCut = Lines.fromPointAndDirection(Vector2D.ZERO, Vector2D.Unit.PLUS_X, precision);
60 final RegionNode2D a = tree.getRoot();
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62 nodeNames.put(a, "a");
63 svgWriter.write(tree, nodeNames, new File(outputFolder, String.format(OUTPUT_FILE_FORMAT, ++cutCount)));
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66 a.cut(rootCut);
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68 final RegionNode2D b = a.getMinus();
69 final RegionNode2D c = a.getPlus();
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71 nodeNames.put(b, "b");
72 nodeNames.put(c, "c");
73 svgWriter.write(tree, nodeNames, new File(outputFolder, String.format(OUTPUT_FILE_FORMAT, ++cutCount)));
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76 b.insertCut(Lines.fromPoints(Vector2D.of(1, 0), Vector2D.of(-1, 1), precision));
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78 final RegionNode2D d = b.getMinus();
79 final RegionNode2D e = b.getPlus();
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81 nodeNames.put(d, "d");
82 nodeNames.put(e, "e");
83 svgWriter.write(tree, nodeNames, new File(outputFolder, String.format(OUTPUT_FILE_FORMAT, ++cutCount)));
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85 d.insertCut(Lines.fromPointAndDirection(Vector2D.of(-5, 1), Vector2D.Unit.MINUS_Y, precision));
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87 final RegionNode2D f = d.getMinus();
88 final RegionNode2D g = d.getPlus();
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90 nodeNames.put(f, "f");
91 nodeNames.put(g, "g");
92 svgWriter.write(tree, nodeNames, new File(outputFolder, String.format(OUTPUT_FILE_FORMAT, ++cutCount)));
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95 c.insertCut(Lines.fromPoints(Vector2D.of(-1, 0), Vector2D.of(1, -1), precision));
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97 final RegionNode2D h = c.getMinus();
98 final RegionNode2D i = c.getPlus();
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100 nodeNames.put(h, "h");
101 nodeNames.put(i, "i");
102 svgWriter.write(tree, nodeNames, new File(outputFolder, String.format(OUTPUT_FILE_FORMAT, ++cutCount)));
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104 h.insertCut(Lines.fromPointAndDirection(Vector2D.of(5, -1), Vector2D.Unit.PLUS_Y, precision));
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106 final RegionNode2D j = h.getMinus();
107 final RegionNode2D k = h.getPlus();
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109 nodeNames.put(j, "j");
110 nodeNames.put(k, "k");
111 svgWriter.write(tree, nodeNames, new File(outputFolder, String.format(OUTPUT_FILE_FORMAT, ++cutCount)));
112 }
113 }