feat: Added raycaster (concept only no drawing yet)

Almost copy pasted from https://github.com/herbievine/42/blob/main/cub3d
but it's also copied from Lodev's ressource

src/raycast/ray.c

@@ -0,0 +1,107 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ray.c                                              :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: tchampio <tchampio@student.42lehavre.fr>   +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2025/07/30 12:10:17 by tchampio          #+#    #+#             */
+/*   Updated: 2025/07/30 12:36:11 by tchampio         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "ray.h"
+#include "../player/player.h"
+#include "../consts.h"
+#include "../cub3d_data.h"
+#include <math.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, char **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 = 0;
+		}
+		else
+		{
+			ray->side_dist_y += ray->delta_dist_y;
+			ray->map_y += ray->step_y;
+			ray->side = 1;
+		}
+		if (map[ray->map_y][ray->map_x] != '0')
+			break ;
+	}
+	if (ray->side == 0)
+		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)
+{
+	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_start = HEIGHT - 1;
+	if (ray->side == 0)
+		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->map);
+		calculate_wall_height(ray, &data->player);
+	}
+}

src/raycast/ray.h

@@ -0,0 +1,37 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ray.h                                              :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: tchampio <tchampio@student.42lehavre.      +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2025/07/29 11:32:20 by tchampio          #+#    #+#             */
+/*   Updated: 2025/07/29 11:35:17 by tchampio         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#ifndef RAY_H
+# define RAY_H
+
+typedef struct s_ray
+{
+	double	plane;
+	double	dir_x;
+	double	dir_y;
+	int	map_x;
+	int	map_y;
+	int	step_x;
+	int	step_y;
+	double	side_dist_x;
+	double	side_dist_y;
+	double	delta_dist_x;
+	double	delta_dist_y;
+	double	wall_dist;
+	int	side;
+	int	wall_height;
+	int	draw_start;
+	int	draw_end;
+	double	wall_x;
+}	t_ray;
+
+#endif // RAY_H