light.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   light.c                                            :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: mghalmi <mghalmi@student.42.fr>            +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/01/27 15:36:50 by mghalmi           #+#    #+#             */
/*   Updated: 2024/02/08 13:25:27 by mghalmi          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "main.h"

void	add_coeficient(double (*rgb)[3], double coef, int color)
{
	unsigned int	mask;

	mask = 255 << 16;
	(*rgb)[0] += coef * ((color & mask) >> 16) / 255;
	mask >>= 8;
	(*rgb)[1] += coef * ((color & mask) >> 8) / 255;
	mask >>= 8;
	(*rgb)[2] += coef * (color & mask) / 255;
}

void	compute_light(t_inter *inter, t_scene data, t_obj *lst)
{
	double			light;
	double			rgb[3];
	t_point			direction;

	light = 0.0;
	ft_memset(rgb, 0, 3 * sizeof(double));
	add_coeficient(&rgb, data.ambient_light, data.al_color);
	while (data.l)
	{
		direction = vsubstr(data.l->o, inter->p);
		if (is_lit(inter->p, direction, lst) \
				&& dot(inter->normal, direction) > 0)
		{
			light = data.l->br * vcos(inter->normal, direction);
			add_coeficient(&rgb, light, data.l->color);
		}
		data.l = data.l->next;
	}
	inter->color = color_x_light(inter->color, rgb);
}

void	calc_normal(t_point p, t_point d, t_point *normal, t_obj *l)
{
	if (l->flag == SP)
	{
		*normal = normalize(vsubstr(p, l->fig.sp.c));
		if (vcos(d, *normal) > 0)
		{
			*normal = scal_x_vec(-1, *normal);
			l->fig.sp.inside = 1;
		}
		else
			l->fig.sp.inside = 0;
	}
	else
	{
		if (vcos(d, l->normal) > 0)
			*normal = scal_x_vec(-1, l->normal);
		else
			*normal = l->normal;
	}
}

int	is_lit(t_point o, t_point d, t_obj *lst)
{
	double	in;

	while (lst)
	{
		if (lst->flag == SP)
			in = sphere_intersection(o, d, lst);
		else if (lst->flag == PL)
			in = plane_intersection(o, d, lst);
		else if (lst->flag == CY)
			in = cylinder_intersection(o, d, lst);
		if (in > EPSILON && in < 1)
			return (0);
		lst = lst->next;
	}
	return (1);
}