GeoUtils.cpp

#include "GeoUtils.h"
#include "Core.h"

double jmk::areaTriangle2d(const Point2d& a, const Point2d& b, const Point2d &c)
{
    auto AB = b - a;
    auto AC = c - a;

    auto result = crossProduct2D(AB, AC);

    return result/2;
}

int jmk::orientation2d(const Point2d& a, const Point2d& b, const Point2d& c)
{
    auto area = areaTriangle2d(a, b, c);

    if (area > 0 && area < TOLERANCE) {
        area = 0;
    }

    if (area < 0 && area > TOLERANCE) {
        area = 0;
    }

    Vector2f ab = b - a;
    Vector2f ac = c - a;

    if (area > 0) {
        return static_cast<int>(RELATIVE_POSITION::LEFT);
    }
    if (area < 0) {
        return static_cast<int>(RELATIVE_POSITION::RIGHT);
    }
    if ((ab[X] * ac[X] < 0) || (ab[Y] * ac[Y] < 0)) {
        return static_cast<int>(RELATIVE_POSITION::BEHIND);
    }
    if (ab.magnitude() < ac.magnitude()) {
        return static_cast<int>(RELATIVE_POSITION::BEYOND);
    }
    if (a == c) {
        return static_cast<int>(RELATIVE_POSITION::ORIGIN);
    }
    if (b == c) {
        return static_cast<int>(RELATIVE_POSITION::DESTINATION);
    }

    return static_cast<int>(RELATIVE_POSITION::BETWEEN);
}