/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   maths_cylinder.c                                   :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: gbrochar <marvin@42.fr>                    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/02/08 18:31:29 by gbrochar          #+#    #+#             */
/*   Updated: 2019/02/22 17:26:27 by gbrochar         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "rtv1.h"

double					intersect_cylinder(void *obj, t_ray r)
{
	t_cylinder			*cy;
	t_vec				sub_ori;
	double				roots[2];
	double				params[3];

	cy = (t_cylinder *)obj;
	sub_ori = vec_sub(r.o, cy->o);
	params[0] = dot_product(r.d, r.d) - pow(dot_product(r.d, cy->d), 2);
	params[1] = (double)2 * (dot_product(r.d, sub_ori)
			- (dot_product(r.d, cy->d) * dot_product(sub_ori, cy->d)));
	params[2] = dot_product(sub_ori, sub_ori)
		- pow(dot_product(sub_ori, cy->d), 2) - pow(cy->r, 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_cylinder(void *obj, t_ray r, double t)
{
	t_cylinder			*cy;
	t_vec				p;
	double				m;

	cy = (t_cylinder *)obj;
	p = vec_add(r.o, vec_mul(r.d, t));
	m = dot_product(r.d, cy->d) * t
		+ dot_product(vec_sub(r.o, cy->o), cy->d);
	p = vec_sub(vec_sub(p, cy->o), vec_mul(cy->d, m));
	normalize(&p);
	return (p);
}