/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   phong.c                                            :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: gbrochar <marvin@42.fr>                    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/02/08 15:38:13 by gbrochar          #+#    #+#             */
/*   Updated: 2019/02/22 18:12:11 by gbrochar         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "rtv1.h"

t_ray					get_light_ray(t_ray r, double t, t_spot spot)
{
	t_ray				l_r;

	l_r.o = vec_add(r.o, vec_mul(r.d, t));
	l_r.d = vec_sub(spot.o, l_r.o);
	normalize(&l_r.d);
	return (l_r);
}

double					get_intensity(t_env *e, t_ray r,
		t_spot spot, t_obj_list obj)
{
	t_ray				l_r;
	t_vec				normal;
	double				length;
	double				i;

	l_r = get_light_ray(r, obj.t, spot);
	length = vec_length(vec_sub(spot.o, l_r.o));
	normal = e->func.normal_obj[obj.type](obj.obj, r, obj.t);
	i = dot_product(l_r.d, normal);
	if (i > 0)
		return ((spot.i * i) / (length * length));
	return (0);
}

int						intersect_phong(t_env *e, t_ray r,
		t_spot spot, t_obj_list obj)
{
	t_ray				l_r;
	double				length;
	t_obj_list			*ret;

	l_r = get_light_ray(r, obj.t, spot);
	length = vec_length(vec_sub(spot.o, l_r.o));
	if (!(ret = intersect_ray(e, l_r)) || ret->t > length)
		return (SUCCESS);
	return (FAILURE);
}

double					get_specular(t_env *e, t_ray ray,
		t_spot spot, t_obj_list obj)
{
	t_vec				normal;
	t_vec				i;
	t_vec				r;
	t_vec				v;
	double				spec_coef;

	v = vec_sub(ray.o, vec_add(ray.o, vec_mul(ray.d, obj.t)));
	i = vec_sub(vec_add(ray.o, vec_mul(ray.d, obj.t)), spot.o);
	normal = e->func.normal_obj[obj.type](obj.obj, ray, obj.t);
	normalize(&i);
	r = get_r_vec(v, normal);
	normalize(&r);
	spec_coef = dot_product(r, i);
	if (spec_coef > M_PI / 2 - e->spec_radius
			&& spec_coef < M_PI / 2 + e->spec_radius
			&& dot_product(normal, vec_mul(i, -1)) > 0)
		return ((spec_coef + e->spec_radius - M_PI / 2) * e->spec_ratio);
	return (0);
}

t_color					phong(t_env *e, t_ray r, t_obj_list *obj)
{
	t_spot_list			*browser;
	t_obj_list			backup;
	double				i;
	double				specular;

	i = 0;
	specular = 0;
	backup = *obj;
	browser = e->spots;
	while (browser)
	{
		if (SUCCESS == intersect_phong(e, r, browser->spot, backup))
			i += get_intensity(e, r, browser->spot, backup);
		specular += get_specular(e, r, browser->spot, backup);
		browser = browser->next;
	}
	if (i > 1)
		i = 1;
	return (color_cap(color_add(
					color_mul(obj->c, e->ambient
						+ ((double)1 - e->ambient) * i),
					color_mul(color(255, 255, 255), specular))));
}