/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   maths_cone.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: gbrochar <marvin@42.fr>                    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/02/08 20:02:35 by gbrochar          #+#    #+#             */
/*   Updated: 2019/02/22 17:26:00 by gbrochar         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "rtv1.h"

double					intersect_cone(void *obj, t_ray r)
{
	t_cone				*co;
	t_vec				sub_ori;
	double				params[3];
	double				roots[2];

	co = (t_cone *)obj;
	sub_ori = vec_sub(r.o, co->o);
	params[0] = dot_product(r.d, r.d) - (pow(co->k, 2) + (double)1)
		* pow(dot_product(r.d, co->d), 2);
	params[1] = (double)2 * (dot_product(r.d, sub_ori)
			- (pow(co->k, 2) + (double)1) * dot_product(r.d, co->d)
			* dot_product(sub_ori, co->d));
	params[2] = dot_product(sub_ori, sub_ori) - (pow(co->k, 2) + (double)1)
		* pow(dot_product(sub_ori, co->d), 2);
	if (SUCCESS == solve_quadratic(params, roots))
	{
		if (roots[0] > 0)
			return (roots[0] - E);
		else if (roots[1] > 0)
			return (roots[1] - E);
	}
	return (FAILURE);
}

t_vec					normal_cone(void *obj, t_ray r, double t)
{
	t_cone				*co;
	t_vec				p;
	double				m;

	co = (t_cone *)obj;
	p = vec_add(r.o, vec_mul(r.d, t));
	m = dot_product(r.d, co->d) * t
		+ dot_product(vec_sub(r.o, co->o), co->d);
	p = vec_sub(vec_sub(vec_sub(p, co->o), vec_mul(co->d, m)),
			vec_mul(co->d, m * pow(co->k, 2)));
	normalize(&p);
	return (p);
}