From 7ba83f1772387a22ccd42bcc3c3d299dcccb2f5e Mon Sep 17 00:00:00 2001
From: Willem Haffmans <info@willemhaffmans.nl>
Date: Fri, 2 May 2025 17:01:15 +0200
Subject: [PATCH] first DDA scratch

---
 src/render/DDAscratch.c | 77 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 src/render/DDAscratch.c

diff --git a/src/render/DDAscratch.c b/src/render/DDAscratch.c
new file mode 100644
index 0000000..880ac20
--- /dev/null
+++ b/src/render/DDAscratch.c
@@ -0,0 +1,77 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        ::::::::            */
+/*   DDAscratch.c                                       :+:    :+:            */
+/*                                                     +:+                    */
+/*   By: whaffman <whaffman@student.codam.nl>         +#+                     */
+/*                                                   +#+                      */
+/*   Created: 2025/05/02 11:58:09 by whaffman      #+#    #+#                 */
+/*   Updated: 2025/05/02 16:57:20 by whaffman      ########   odam.nl         */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "cub3d.h"
+
+t_vec2	get_delta_dist(t_vec2 ray_dir)
+{
+	t_vec2	delta_dist;
+
+	delta_dist.x = (ray_dir.x == 0) * 1e30 + (ray_dir.x != 0) * fabs(1 / ray_dir.x);
+	delta_dist.y = (ray_dir.y == 0) * 1e30 + (ray_dir.y != 0) * fabs(1 / ray_dir.y);
+	return (delta_dist);
+}
+
+t_vec2	get_step(t_vec2 ray_dir)
+{
+	t_vec2	step;
+
+	step.x = 2 * (ray_dir.x >= 0) - 1;
+	step.y = 2 * (ray_dir.y >= 0) - 1;
+	return (step);
+}
+
+t_vec2 get_side_dist(t_vec2 ray_dir, t_vec2 pos, t_vec2 delta_dist)
+{
+	const t_vec2	frac_pos = (t_vec2){pos.x - (int)pos.x, pos.y - (int)pos.y};
+	const int		raydir_x_pos = (ray_dir.x >= 0);
+	const int		raydir_y_pos = (ray_dir.y >= 0);
+	t_vec2 			side_dist;
+
+	side_dist.x = ((1 - raydir_x_pos) * frac_pos.x + raydir_x_pos * (1 - frac_pos.x)) * delta_dist.x;
+	side_dist.y = ((1 - raydir_y_pos) * frac_pos.y + raydir_x_pos * (1 - frac_pos.y)) * delta_dist.y;
+	return (side_dist);
+}
+
+int DDA_main(t_vec2 ray_dir, t_vec2_int map_pos, t_vec2 *side_dist, t_map *map)
+{
+	const t_vec2 delta_dist = get_delta_dist(ray_dir);
+	const t_vec2 step = get_step(ray_dir);
+	int side;
+
+	while (1)
+	{
+		side = (side_dist->x >= side_dist->y);
+		side_dist->x += delta_dist.x * (1 - side);
+		side_dist->y += delta_dist.y * side;
+		map_pos.x += step.x * (1 - side);
+		map_pos.y += step.y * side;
+		if (map->grid[map_pos.y][map_pos.x] == TILE_WALL)
+			break;
+	}
+	return (side);
+}
+
+// Returns the distance to the wall hit if the wall is hit in y direction the result is
+// negative, if the wall is hit in x direction the result is positive
+int DDA(t_vec2 ray_dir, t_vec2 pos, t_map *map)
+{
+	const t_vec2	delta_dist = get_delta_dist(ray_dir);
+	t_vec2 			side_dist;
+	int 			side;
+
+	side_dist = get_side_dist(ray_dir, pos, delta_dist);
+	side = DDA_main(ray_dir,(t_vec2_int) {(int)pos.x, (int)pos.y}, &side_dist, map);
+	return (1 - side) * (side_dist.x - delta_dist.x) - side * (side_dist.y - delta_dist.y);
+}
+
+