cub3d/src/raycast/ray.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ray.c                                              :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kcolin <kcolin@42.fr>                      +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2025/07/31 11:55:41 by kcolin            #+#    #+#             */
/*   Updated: 2025/08/20 12:48:06 by tchampio         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "ray.h"
#include "raycaster.h"
#include "../player/player.h"
#include "../consts.h"
#include "../cub3d_data.h"
#include <float.h>
#include <math.h>
#include "../map/collision.h"

void	init_ray(t_ray *ray, int pos_x, t_player *player)
{
	ray->plane = 2 * pos_x / (double)WIDTH - 1;
	ray->dir_x = player->dir_x + player->plane_x * ray->plane;
	ray->dir_y = player->dir_y + player->plane_y * ray->plane;
	ray->map_x = (int)player->x;
	ray->map_y = (int)player->y;
	ray->delta_dist_x = fabs(1 / ray->dir_x);
	ray->delta_dist_y = fabs(1 / ray->dir_y);
}

void	ray_calculate_step(t_ray *ray, t_player *player)
{
	if (ray->dir_x < 0)
	{
		ray->step_x = -1;
		ray->side_dist_x = (player->x - ray->map_x) * ray->delta_dist_x;
	}
	else
	{
		ray->step_x = 1;
		ray->side_dist_x = (ray->map_x + 1.0 - player->x) * ray->delta_dist_x;
	}
	if (ray->dir_y < 0)
	{
		ray->step_y = -1;
		ray->side_dist_y = (player->y - ray->map_y) * ray->delta_dist_y;
	}
	else
	{
		ray->step_y = 1;
		ray->side_dist_y = (ray->map_y + 1.0 - player->y) * ray->delta_dist_y;
	}
}

void	calculate_wall_dist(t_ray *ray, t_mapdata *map)
{
	while (true)
	{
		if (ray->side_dist_x < ray->side_dist_y)
		{
			ray->side_dist_x += ray->delta_dist_x;
			ray->map_x += ray->step_x;
			ray->side = NORTH;
		}
		else
		{
			ray->side_dist_y += ray->delta_dist_y;
			ray->map_y += ray->step_y;
			ray->side = SOUTH;
		}
		if (blocks_view(map, ray->map_x, ray->map_y))
			break ;
	}
	if (ray->side == NORTH)
		ray->wall_dist = ray->side_dist_x - ray->delta_dist_x;
	else
		ray->wall_dist = ray->side_dist_y - ray->delta_dist_y;
}

void	calculate_wall_height(t_ray *ray, t_player *player)
{
	if (ray->wall_dist <= FLT_EPSILON)
		ray->wall_dist = 0.1;
	ray->wall_height = (int)(HEIGHT / ray->wall_dist);
	ray->draw_start = -ray->wall_height / 2 + HEIGHT / 2;
	if (ray->draw_start < 0)
		ray->draw_start = 0;
	ray->draw_end = ray->wall_height / 2 + HEIGHT / 2;
	if (ray->draw_end >= HEIGHT)
		ray->draw_end = HEIGHT - 1;
	if (ray->side == NORTH)
		ray->wall_x = player->y + ray->wall_dist * ray->dir_y;
	else
		ray->wall_x = player->x + ray->wall_dist * ray->dir_x;
	ray->wall_x -= floor(ray->wall_x);
}

void	raycaster(t_cub3d_data *data, t_ray *ray)
{
	int	x;

	x = 0;
	while (x < WIDTH)
	{
		init_ray(ray, x, &data->player);
		ray_calculate_step(ray, &data->player);
		calculate_wall_dist(ray, data->map);
		calculate_wall_height(ray, &data->player);
		render_walls(data, ray, x);
		data->zbuffer[x] = ray->wall_dist;
		x++;
	}
}