geom.cpp

//#include <iostream> //

#include "geom.h"

double isEqual(double a, double b, double eps) {
    return (fabs(a - b) < eps);
}

double NormAngle(double a) {
    while (a < -M_PI) {
        a += M_PI * 2;
    }
    while (a > M_PI) {
        a -= M_PI * 2;
    }

    return a;
}

double Pif2(double a, double b) {
    return a*a + b*b;
}

double Pif(double a, double b) {
    return sqrt(Pif2(a, b));
}

double ctg(double a) {
    return 1 / tan(a);
}

double vectorMul(double x1, double y1, double x2, double y2) {
    return x1 * y2 - x2 * y1;
}

double scalarMul(double x1, double y1, double x2, double y2) {
    return x1 * x2 + y1 * y2;
}

double orientedS(double x1, double y1, double x2, double y2, double x3, double y3) {
    return vectorMul(x2 - x1, y2 - y1, x3 - x1, y3 - y1);
}

bool intersection(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4,
                  double& x, double& y)
{
    const double a1 = y1 - y2;
    const double b1 = x2 - x1;
    const double c1 = x1*y2 - x2*y1;

    const double a2 = y3 - y4;
    const double b2 = x4 - x3;
    const double c2 = x3*y4 - x4*y3;

    const double d = a1*b2 - a2*b1;

    if (d == 0) {
        return false;
    }

    x = (b1*c2 - b2*c1) / d;
    y = (a2*c1 - a1*c2) / d;
    return true;
}

double height(double x, double y, double x1, double y1, double x2, double y2) {
    const double a = y1 - y2;
    const double b = x2 - x1;
    const double c = x1*y2 - x2*y1;

    return fabs(a*x + b*y + c) / Pif(a, b);
}

double sqr(double a) {
    return a * a;
}