/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   maths_sphere.c                                     :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: gbrochar <marvin@42.fr>                    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/02/08 14:43:58 by gbrochar          #+#    #+#             */
/*   Updated: 2019/02/11 14:15:57 by gbrochar         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "rtv1.h"

double					intersect_sphere(void *obj, t_ray r)
{
	t_sphere			*s;
	double				roots[2];
	double				params[3];

	s = (t_sphere *)obj;
	params[0] = 1;
	params[1] = (double)2 * dot_product(r.d, vec_sub(r.o, s->o));
	params[2] = dot_product(vec_sub(r.o, s->o), vec_sub(r.o, s->o))
		- s->r * s->r;
	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_sphere(void *obj, t_ray r, double t)
{
	t_sphere			*s;
	t_vec				p;

	s = (t_sphere *)obj;
	p = vec_add(r.o, vec_mul(r.d, t));
	p = vec_sub(p, s->o);
	normalize(&p);
	return (p);
}