From af9106bae54f3584ae1fa8b531670f9dfbc20153 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Sun, 3 Nov 2024 22:10:37 +0000
Subject: [PATCH] Draw maze while generating it

---
 main.c | 82 +++++++++++++++++++++++++++++++---------------------------
 1 file changed, 44 insertions(+), 38 deletions(-)

diff --git a/main.c b/main.c
index ddda221..3fc1f73 100644
--- a/main.c
+++ b/main.c
@@ -3,12 +3,15 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+#define _POSIX_C_SOURCE 199309L
+
 #include <X11/Xlib.h>
 #include <assert.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>
+#include <time.h>
 
 #define MAZE_SIZE 24
 
@@ -31,6 +34,8 @@ typedef struct {
 	int x, y;
 } vec2_t;
 
+static const struct timespec pause = { .tv_nsec = 5000000 };
+
 static const vec2_t steps[] = {
 	[LEFT] = { .x = -2, .y = 0 },
 	[RIGHT] = { .x = 2, .y = 0 },
@@ -38,44 +43,10 @@ static const vec2_t steps[] = {
 	[DOWN] = { .x = 0, .y = 2 },
 };
 
-static void generate_step(maze_t *m, int x, int y)
-{
-	m->cells[x][y] = true;
-	if (GOAL == x && GOAL == y)
-		return;
-
-	dir_t visit[] = { LEFT, RIGHT, UP, DOWN };
-	for (int i = 3; i > 0; --i) {
-		const int r = rand() % (i + 1);
-		const dir_t tmp = visit[r];
-		visit[r] = visit[i];
-		visit[i] = tmp;
-	}
-
-	for (int i = 0; i < 4; ++i) {
-		const int xp = x + steps[visit[i]].x;
-		const int yp = y + steps[visit[i]].y;
-
-		const bool x_in_bounds = xp >= 0 && xp < GRID_SIZE;
-		const bool y_in_bounds = yp >= 0 && yp < GRID_SIZE;
-		if (x_in_bounds && y_in_bounds && !m->cells[xp][yp]) {
-			const int xi = (x + xp) / 2;
-			const int yi = (y + yp) / 2;
-			m->cells[xi][yi] = true;
-
-			generate_step(m, xp, yp);
-		}
-	}
-}
-
-static void generate_maze(maze_t *m)
-{
-	memset(m, 0, sizeof(maze_t));
-	generate_step(m, 0, 0);
-}
-
 static void draw_maze(Display *dpy, Window w, GC gc, const maze_t *m)
 {
+	XClearWindow(dpy, w);
+
 	// Draw walls
 	XFillRectangle(
 	    dpy, w, gc, PX(MARGIN), PX(MARGIN), PX(GRID_SIZE + 2),
@@ -104,6 +75,41 @@ static void draw_maze(Display *dpy, Window w, GC gc, const maze_t *m)
 	XFlush(dpy);
 }
 
+static void
+generate_maze(Display *dpy, Window w, GC gc, maze_t *m, int x, int y)
+{
+	m->cells[x][y] = true;
+
+	draw_maze(dpy, w, gc, m);
+	nanosleep(&pause, NULL);
+
+	if (GOAL == x && GOAL == y)
+		return;
+
+	dir_t visit[] = { LEFT, RIGHT, UP, DOWN };
+	for (int i = 3; i > 0; --i) {
+		const int r = rand() % (i + 1);
+		const dir_t tmp = visit[r];
+		visit[r] = visit[i];
+		visit[i] = tmp;
+	}
+
+	for (int i = 0; i < 4; ++i) {
+		const int xp = x + steps[visit[i]].x;
+		const int yp = y + steps[visit[i]].y;
+
+		const bool x_in_bounds = xp >= 0 && xp < GRID_SIZE;
+		const bool y_in_bounds = yp >= 0 && yp < GRID_SIZE;
+		if (x_in_bounds && y_in_bounds && !m->cells[xp][yp]) {
+			const int xi = (x + xp) / 2;
+			const int yi = (y + yp) / 2;
+			m->cells[xi][yi] = true;
+
+			generate_maze(dpy, w, gc, m, xp, yp);
+		}
+	}
+}
+
 int main(void)
 {
 	// Seed random number generation from time
@@ -135,8 +141,8 @@ int main(void)
 
 	// Generate and draw maze
 	maze_t m;
-	generate_maze(&m);
-	draw_maze(dpy, w, gc, &m);
+	memset(&m, 0, sizeof(maze_t));
+	generate_maze(dpy, w, gc, &m, 0, 0);
 
 	// Wait for window exit
 	bool is_del = false;