Bresenham line points

Bresenham line

inline std::vector< std::pair<int,int> > getBresenhamLinePoints(int x1, int y1, int x2, int y2)
{
    std::vector <std::pair<int, int> > out_points;
    bool steep = (std::abs(y2 - y1) > std::abs(x2 - x1));
    if(steep){
        std::swap(x1, y1);
        std::swap(x2, y2);
    }

    if(x1 > x2){
        std::swap(x1, x2);
        std::swap(y1, y2);
    }

    int dx = x2 - x1;
    int dy = std::abs(y2 - y1);

    double err = dx / 2.0f;
    
    int ystep = (y1 < y2)? 1 : -1;
    int y = (y1);

    for (int x = x1; x <= x2; ++x) {
        if(steep){
            // y,x
            out_points.push_back(std::make_pair(y,x));
        } else {
            // x, y
            out_points.push_back(std::make_pair(x, y));
        }
        err = err - dy;
        if(err < 0){
            y = y + ystep;
            err = err +  dx;
        }
    }
    return out_points;
}