111 lines
2.4 KiB
C
111 lines
2.4 KiB
C
#include "polygon.h"
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line getLine(point pt1, point pt2) {
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return (line){.start=pt1, .direction=(point){pt2.x - pt1.x, pt2.y - pt1.y}};
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}
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lines getLines(points pts) {
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line * lns = (line *)malloc(pts.len * sizeof(line));
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int len = pts.len;
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for (int i = 0; i < len; ++i) {
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lns[i] = getLine(pts.arr[i], pts.arr[(i + 1) % len]);
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}
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return (lines){lns, len};
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}
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points getVectors(points pts) {
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point * vectors = (point *)malloc(pts.len * sizeof(point));
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int len = pts.len;
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point vector;
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double vlen;
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for (int i = 0; i < len; ++i) {
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vector = normal(getLine(pts.arr[i], pts.arr[(i + 1) % len]));
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vlen = vector_len(vector);
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vector.x /= vlen, vector.y /= vlen;
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vectors[i] = vector;
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}
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return (points){vectors, len};
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}
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point normal(line ln) {
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return (point){ln.direction.y, -ln.direction.x};
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}
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double vector_len(point vector) {
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return sqrt(qpow(vector.x) + qpow(vector.y));
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}
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double qpow(double number) {
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return number * number;
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}
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void repairPolygon(polygon * plgn) {
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lines lns = getLines(plgn -> pts);
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int len = lns.len;
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for (int i = 0; i < len; ++i) {
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point fdirect = lns.arr[i].direction;
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point sdirect = lns.arr[(i + 1) % len].direction;
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if (isNull(fdirect)) {
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polygonDelPoint(plgn, i), --len;
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delLine(&lns, i--);
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fdirect = sdirect, sdirect = lns.arr[(i + 1) % len].direction;
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}
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if (isCollinear(fdirect, sdirect)) {
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polygonDelPoint(plgn, i), --len;
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delLine(&lns, i--);
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}
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}
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free(lns.arr);
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}
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bool isNull(point vector) {
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return (fabs(vector.x) < eps && fabs(vector.y) < eps);
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}
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void polygonDelPoint(polygon * plgn, int index) {
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delVector(&(plgn -> pts), index);
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}
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bool isCollinear(point fvec, point svec) {
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return fabs(fabs(fvec.x * svec.x + fvec.y * svec.y) - (vector_len(fvec) * vector_len(svec))) < eps;
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}
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DELFUNC(Vector, points)
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DELFUNC(Line, lines)
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polygon getPolygon(polygon * plgn, double shift) {
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points vectors = getVectors(plgn -> pts);
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int secind, len = plgn -> pts.len;
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point * pts = (point *)malloc(len * sizeof(point));
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memcpy(pts, plgn -> pts.arr, len * sizeof(point));
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for (int i = 0; i < len; ++i) {
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vectors.arr[i].x *= shift;
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vectors.arr[i].y *= shift;
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secind = ((i + 1) % len);
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pts[i].x += vectors.arr[i].x;
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pts[secind].x += vectors.arr[i].x;
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pts[i].y += vectors.arr[i].y;
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pts[secind].y += vectors.arr[i].y;
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}
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free(vectors.arr);
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return (polygon){(points){pts, len}};
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}
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