/**
 * Implementation of a spheroid
 **/

#include "spheroid.hpp"

Spheroid::Spheroid(const Point& _center, double _min_p, double _p, double _q) :
    ImplicitSurface(_center), normal_vector(Point(0,0,1)), min_p(_min_p),
    init_p(_p), p(_p), q(_q), stiffness(0)
{
    _compute_volume();
}

void Spheroid::_compute_volume() {
    V = (4/3) * PI * p * q * q;
}



void Spheroid::update_radius() {
    q = sqrt((3/4) * V / PI / p);
}

void Spheroid::update_height() {
    q = (3/4) * V / PI / (p*p);
}


void Spheroid::update_center_pos(Point& _center) {
    center = _center;
}

void Spheroid::check_horizontal_plan_collision(double& height) {
    if ((center.y - p) <= height) {
        p = fmin(init_p, center.y-height);
        update_radius();
    }
}

void Spheroid::check_vertical_plan_collision(double& abscissa) {
    if (center.x <= abscissa) {
        if ((center.x + q) >= abscissa) {
            q = abscissa - center.x;
            update_height();
        }
    } else {
        if ((center.x - q) <= abscissa) {
            q = center.x - abscissa;
            update_height();
        }
    }
}

Cuboid Spheroid::max_bounding_box() const {
    double max_radius = sqrt((3./4.) * V / PI / min_p);
    double max_height = init_p;
    Point _bd1(max_radius, max_radius, max_height);
    Point _bd2(-max_radius, -max_radius, -max_height);
    return Cuboid(_bd1, _bd2);
}

void Spheroid::check_perlin_collision(PerlinNoise perlin) {
    double height = perlin.noise(center.x, center.z);
    if ((center.y - p) <= height) {
        p = fmin(init_p, center.z- height );
        normal_vector = perlin.normal_vector(center.x, center.z);
        update_radius();
    }
}


double Spheroid::operator() (double _x, double _y, double _z) const {
            return (pow(_x, 2) / pow(q, 2)
                  + pow(_y, 2) / pow(q, 2)
                  + pow(_z, 2) / pow(p, 2) -1);
}