91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
#include "SCP.h"
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circle MEC(point * I, int ilen, point * N, int nlen) {
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if (ilen != 0 && nlen < 3) {
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point rnd = I[ilen - 1];
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circle crcl = MEC(I, ilen - 1, N, nlen);
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if (belongs(crcl, rnd)) return crcl;
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else {
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N[nlen++] = rnd;
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return MEC(I, ilen - 1, N, nlen);
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}
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} else return primitive(N, nlen);
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}
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bool belongs(circle crcl, point p) {
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if (powd(p.x - crcl.center.x) + powd(p.y - crcl.center.y) <= exp + powd(crcl.radius)) return true;
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return false;
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}
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double powd(double number) {
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return number * number;
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}
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circle primitive(point * N, int nlen) {
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if (nlen == 3) {
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point temp;
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circle crcl;
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for (int i = 0; i < nlen; ++i) {
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temp = N[2];
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N[2] = N[i];
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N[i] = temp;
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crcl = centermass(N[0], N[1]);
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if (belongs(crcl, N[2])) return crcl;
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N[i] = N[2];
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N[2] = temp;
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}
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return byThreePoints(N);
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} else if (nlen == 2) {
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return centermass(N[0], N[1]);
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} else if (nlen == 1) {
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return (circle){N[0], 0};
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} else {
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return (circle){(point){0, 0}, 0};
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}
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}
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circle centermass(point p1, point p2) {
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return (circle){(point){(p1.x + p2.x) / 2, (p1.y + p2.y) / 2}, distance(p1, p2) / 2};
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}
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circle byThreePoints(point * warp) {
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point center;
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double radius, x, y;
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double ang_a;
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double ang_b;
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if (fabs(warp[1].x - warp[0].x) < exp || fabs(warp[2].x - warp[1].x) < exp) return (circle){.center=(point){0, 0}, .radius=-1};
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ang_a = straightAngle(warp[1], warp[0]);
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ang_b = straightAngle(warp[2], warp[1]);
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if (fabs(ang_b) < exp || fabs(ang_b - ang_a) < exp) {
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return (circle){.center=(point){0, 0}, .radius=-1};
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}
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x = (ang_a * ang_b * (warp[0].y - warp[2].y) + ang_b * (warp[0].x + warp[1].x) - ang_a * (warp[1].x + warp[2].x)) / (2 * (ang_b - ang_a));
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y = (-(1/ang_b) * (x - (warp[1].x + warp[2].x) / 2) + (warp[1].y + warp[2].y) / 2);
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center = (point){x, y};
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radius = distance(center, warp[0]);
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return (circle){center, radius};
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}
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double straightAngle(point p1, point p2) {
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return (p1.y - p2.y) / (p1.x - p2.x);
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}
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double distance(point p1, point p2) {
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return sqrt(powd(p1.x - p2.x) + powd(p1.y - p2.y));
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}
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void printCircle(circle crcl) {
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printf("(x - %.4lf)^2 + (y - %.4lf)^2 = %.4lf^2\n", crcl.center.x, crcl.center.y, crcl.radius);
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// printf("Center of circle at point (%.2lf, %.2lf)\nRadius is %.2lf\n", crcl.center.x, crcl.center.y, crcl.radius);
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}
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