73 lines
2 KiB
C++
73 lines
2 KiB
C++
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#include "Line.h"
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#include <math.h>
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int lineIntersection(const LINE *la, const LINE *lb, Vertex *v) {
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double xa1 = la->v1.getX(), ya1 = la->v1.getY();
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double xa2 = la->v2.getX(), ya2 = la->v2.getY();
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double xb1 = lb->v1.getX(), yb1 = lb->v1.getY();
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double xb2 = lb->v2.getX(), yb2 = lb->v2.getY();
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double temp;
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int switched = 0;
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Vertex v2;
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if(!v) v = &v2;
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if(xa1 == xa2 && ya1 == ya2) return INTERSECTION_ERROR;
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if(xb1 == xb2 && yb1 == yb2) return INTERSECTION_ERROR;
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if(xa1 == xa2 || xb1 == xb2) {
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temp = xa1; xa1 = ya1; ya1 = temp;
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temp = xa2; xa2 = ya2; ya2 = temp;
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temp = xb1; xb1 = yb1; yb1 = temp;
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temp = xb2; xb2 = yb2; yb2 = temp;
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switched = 1;
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}
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if(xa1 == xa2 && xb1 == xb2)
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return (xa1 == xb1) ? INTERSECTION_IDENTICAL : INTERSECTION_NONE;
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if(xa1 == xa2) {
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v->setX(xa1);
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v->setY(yb1);
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}
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else if(xb1 == xb2) {
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v->setX(xb1);
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v->setY(ya1);
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}
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else {
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double ma = (ya2-ya1)/(xa2-xa1);
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double mb = (yb2-yb1)/(xb2-xb1);
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double ba = ya1 - ma*xa1;
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double bb = yb1 - mb*xb1;
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if(ma == mb) return (ba == bb) ? INTERSECTION_IDENTICAL : INTERSECTION_NONE;
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v->setX((bb-ba)/(ma-mb));
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v->setY(ma*v->getX() + ba);
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}
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if(switched) {
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temp = v->getX(); v->setX(v->getY()); v->setY(temp);
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//switch back everything for segment tests
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temp = xa1; xa1 = ya1; ya1 = temp;
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temp = xa2; xa2 = ya2; ya2 = temp;
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temp = xb1; xb1 = yb1; yb1 = temp;
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temp = xb2; xb2 = yb2; yb2 = temp;
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}
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if(v->getX() < fmin(xa1,xa2) || v->getX() > fmax(xa1, xa2) || v->getY() < fmin(ya1,ya2) || v->getY() > fmax(ya1, ya2)) {
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if(v->getX() < fmin(xb1,xb2) || v->getX() > fmax(xb1, xb2) || v->getY() < fmin(yb1,yb2) || v->getY() > fmax(yb1, yb2))
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return INTERSECTION_LINE_LINE;
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else
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return INTERSECTION_LINE_SEGMENT;
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}
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else if(v->getX() < fmin(xb1,xb2) || v->getX() > fmax(xb1, xb2) || v->getY() < fmin(yb1,yb2) || v->getY() > fmax(yb1, yb2))
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return INTERSECTION_SEGMENT_LINE;
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else
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return INTERSECTION_SEGMENT_SEGMENT;
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}
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