cylinder_intersection.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   cylinder_intersection.c                            :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: mghalmi <mghalmi@student.42.fr>            +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/01/27 14:44:22 by mghalmi           #+#    #+#             */
/*   Updated: 2024/02/08 13:40:17 by mghalmi          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "main.h"

int	solve_cylinder(double x[2], t_point o, t_point d, t_obj *lst)
{
	t_point	v;
	t_point	u;
	double	a;
	double	b;
	double	c;

	v = scal_x_vec(dot(d, lst->fig.cy.nv), lst->fig.cy.nv);
	v = vsubstr(d, v);
	u = scal_x_vec(dot(vsubstr(o, lst->fig.cy.c), lst->fig.cy.nv), \
													lst->fig.cy.nv);
	u = vsubstr(vsubstr(o, lst->fig.cy.c), u);
	a = dot(v, v);
	b = 2 * dot(v, u);
	c = dot(u, u) - pow(lst->fig.cy.r, 2);
	x[0] = (-b + sqrt(pow(b, 2) - 4 * a * c)) / (2 * a);
	x[1] = (-b - sqrt(pow(b, 2) - 4 * a * c)) / (2 * a);
	if ((x[0] != x[0] && x[1] != x[1]) || (x[0] < EPSILON && x[1] < EPSILON))
	{
		x[0] = INFINITY;
		x[1] = INFINITY;
		return (0);
	}
	return (1);
}

t_point	calc_cy_normal(double x2[2], t_point o, t_point d, t_obj *lst)
{
	double	dist;
	double	x;

	if ((lst->fig.cy.dist1 >= 0 && lst->fig.cy.dist1 <= lst->fig.cy.h \
				&& x2[0] > EPSILON) && (lst->fig.cy.dist2 >= 0 \
				&& lst->fig.cy.dist2 <= lst->fig.cy.h && x2[1] > EPSILON))
	{
		dist = check_dist(x2, lst);
		x = check_x(x2);
	}
	else if (lst->fig.cy.dist1 >= 0 && lst->fig.cy.dist1 <= lst->fig.cy.h \
														&& x2[0] > EPSILON)
	{
		dist = lst->fig.cy.dist1;
		x = x2[0];
	}
	else
	{
		dist = lst->fig.cy.dist2;
		x = x2[1];
	}
	x2[0] = x;
	return (normalize(vsubstr(vsubstr(scal_x_vec(x, d), \
			scal_x_vec(dist, lst->fig.cy.nv)), vsubstr(lst->fig.cy.c, o))));
}

double	cy_intersection(t_point o, t_point d, t_point *normal, t_obj *lst)
{
	double	x2[2];

	if (solve_cylinder(x2, o, d, lst) == 0)
		return (INFINITY);
	lst->fig.cy.dist1 = dot(lst->fig.cy.nv, vsubstr(scal_x_vec(x2[0], d), \
												vsubstr(lst->fig.cy.c, o)));
	lst->fig.cy.dist2 = dot(lst->fig.cy.nv, vsubstr(scal_x_vec(x2[1], d), \
												vsubstr(lst->fig.cy.c, o)));
	if (!((lst->fig.cy.dist1 >= 0 && lst->fig.cy.dist1 <= lst->fig.cy.h \
					&& x2[0] > EPSILON) || (lst->fig.cy.dist2 >= 0 \
					&& lst->fig.cy.dist2 <= lst->fig.cy.h && x2[0] > EPSILON)))
		return (INFINITY);
	*normal = calc_cy_normal(x2, o, d, lst);
	return (x2[0]);
}

double	caps_intersection(t_point o, t_point d, t_obj *lst)
{
	double	id1;
	double	id2;
	t_point	ip1;
	t_point	ip2;
	t_point	c2;

	c2 = vadd(lst->fig.cy.c, scal_x_vec(lst->fig.cy.h, lst->fig.cy.nv));
	id1 = solve_plane(o, d, lst->fig.cy.c, lst->fig.cy.nv);
	id2 = solve_plane(o, d, c2, lst->fig.cy.nv);
	if (id1 < INFINITY || id2 < INFINITY)
	{
		ip1 = vadd(o, scal_x_vec(id1, d));
		ip2 = vadd(o, scal_x_vec(id2, d));
		if ((id1 < INFINITY && distance(ip1, lst->fig.cy.c) <= lst->fig.cy.r) \
				&& (id2 < INFINITY && distance(ip2, c2) <= lst->fig.cy.r))
			select_closest(id1, id2);
		else if (id1 < INFINITY \
						&& distance(ip1, lst->fig.cy.c) <= lst->fig.cy.r)
			return (id1);
		else if (id2 < INFINITY && distance(ip2, c2) <= lst->fig.cy.r)
			return (id2);
		return (INFINITY);
	}
	return (INFINITY);
}

double	cylinder_intersection(t_point o, t_point d, t_obj *lst)
{
	double	cylinder_inter;
	double	caps_inter;
	t_point	cy_normal;

	cylinder_inter = cy_intersection(o, d, &cy_normal, lst);
	caps_inter = caps_intersection(o, d, lst);
	if (cylinder_inter < INFINITY || caps_inter < INFINITY)
	{
		if (cylinder_inter < caps_inter)
		{
			lst->normal = cy_normal;
			return (cylinder_inter);
		}
		lst->normal = lst->fig.cy.nv;
		return (caps_inter);
	}
	return (INFINITY);
}