48 lines
1.4 KiB
Java
48 lines
1.4 KiB
Java
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import java.awt.geom.Line2D;
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import java.util.Random;
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public class PointToSegmentDistance {
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public static double pointToSegmentDistance(int x, int y, int x1, int y1, int x2, int y2) {
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long dx = x2 - x1;
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long dy = y2 - y1;
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long px = x - x1;
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long py = y - y1;
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long squaredLength = dx * dx + dy * dy;
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long dotProduct = dx * px + dy * py;
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if (dotProduct <= 0 || squaredLength == 0)
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return fastHypot(px, py);
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if (dotProduct >= squaredLength)
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return fastHypot(px - dx, py - dy);
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double q = (double) dotProduct / squaredLength;
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return fastHypot(px - q * dx, py - q * dy);
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}
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static double fastHypot(double x, double y) {
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return Math.sqrt(x * x + y * y);
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}
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// Line2D.ptLineDist
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public static double pointToLineDistance(long x, long y, long a, long b, long c) {
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return Math.abs(a * x + b * y + c) / fastHypot(a, b);
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}
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// random test
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public static void main(String[] args) {
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Random rnd = new Random(1);
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for (int step = 0; step < 1000_000; step++) {
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int r = 10;
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int x = rnd.nextInt(r) - r / 2;
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int y = rnd.nextInt(r) - r / 2;
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int x1 = rnd.nextInt(r) - r / 2;
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int y1 = rnd.nextInt(r) - r / 2;
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int x2 = rnd.nextInt(r) - r / 2;
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int y2 = rnd.nextInt(r) - r / 2;
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double res1 = pointToSegmentDistance(x, y, x1, y1, x2, y2);
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double res2 = Line2D.ptSegDist(x1, y1, x2, y2, x, y);
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if (!(Math.abs(res1 - res2) < 1e-9))
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throw new RuntimeException();
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}
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}
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}
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