57 lines
1.7 KiB
Java
57 lines
1.7 KiB
Java
import static java.lang.Math.*;
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public class RayCasting {
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static boolean intersects(int[] A, int[] B, double[] P) {
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if (A[1] > B[1])
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return intersects(B, A, P);
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if (P[1] == A[1] || P[1] == B[1])
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P[1] += 0.0001;
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if (P[1] > B[1] || P[1] < A[1] || P[0] >= max(A[0], B[0]))
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return false;
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if (P[0] < min(A[0], B[0]))
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return true;
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double red = (P[1] - A[1]) / (double) (P[0] - A[0]);
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double blue = (B[1] - A[1]) / (double) (B[0] - A[0]);
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return red >= blue;
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}
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static boolean contains(int[][] shape, double[] pnt) {
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boolean inside = false;
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int len = shape.length;
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for (int i = 0; i < len; i++) {
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if (intersects(shape[i], shape[(i + 1) % len], pnt))
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inside = !inside;
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}
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return inside;
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}
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public static void main(String[] a) {
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double[][] testPoints = {{10, 10}, {10, 16}, {-20, 10}, {0, 10},
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{20, 10}, {16, 10}, {20, 20}};
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for (int[][] shape : shapes) {
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for (double[] pnt : testPoints)
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System.out.printf("%7s ", contains(shape, pnt));
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System.out.println();
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}
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}
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final static int[][] square = {{0, 0}, {20, 0}, {20, 20}, {0, 20}};
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final static int[][] squareHole = {{0, 0}, {20, 0}, {20, 20}, {0, 20},
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{5, 5}, {15, 5}, {15, 15}, {5, 15}};
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final static int[][] strange = {{0, 0}, {5, 5}, {0, 20}, {5, 15}, {15, 15},
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{20, 20}, {20, 0}};
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final static int[][] hexagon = {{6, 0}, {14, 0}, {20, 10}, {14, 20},
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{6, 20}, {0, 10}};
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final static int[][][] shapes = {square, squareHole, strange, hexagon};
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}
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