sphere_intersection.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   sphere_intersection.c                              :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: mghalmi <mghalmi@student.42.fr>            +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/01/28 11:40:38 by mghalmi           #+#    #+#             */
/*   Updated: 2024/02/08 13:41:40 by mghalmi          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "main.h"

void	solve_sphere(double x[2], t_point o, t_point d, t_obj *lst)
{
	double	disc;
	t_point	oc;
	double	k[3];

	oc = vsubstr(o, lst->fig.sp.c);
	k[0] = dot(d, d);
	k[1] = 2 * dot(d, oc);
	k[2] = dot(oc, oc) - lst->fig.sp.r * lst->fig.sp.r;
	disc = k[1] * k[1] - (4 * k[0] * k[2]);
	if (disc < 0)
	{
		x[0] = INFINITY;
		x[1] = INFINITY;
		return ;
	}
	x[0] = (-k[1] + sqrt(disc)) / (2 * k[0]);
	x[1] = (-k[1] - sqrt(disc)) / (2 * k[0]);
}

double	return_x(double x[2])
{
	if (x[0] < x[1])
		return (x[0]);
	return (x[1]);
}

double	sphere_intersection(t_point o, t_point d, t_obj *lst)
{
	double	closest;
	double	x[2];

	closest = INFINITY;
	solve_sphere(x, o, d, lst);
	if (x[0] > EPSILON && x[0] < INFINITY)
		closest = x[0];
	if (x[1] > EPSILON && x[1] < INFINITY)
		if (x[1] < x[0])
			closest = x[1];
	return (closest);
}