Userspace: Implement basic snake game :)

userspace/CMakeLists.txt

@@ -9,6 +9,7 @@ set(USERSPACE_PROJECTS
 	init
 	ls
 	Shell
+	snake
 	stat
 	tee
 	test

userspace/snake/CMakeLists.txt

@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(snake CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(snake ${SOURCES})
+target_compile_options(snake PUBLIC -O2 -g)
+target_link_libraries(snake PUBLIC libc)
+
+add_custom_target(snake-install
+	COMMAND sudo cp ${CMAKE_CURRENT_BINARY_DIR}/snake ${BANAN_BIN}/
+	DEPENDS snake
+	USES_TERMINAL
+)

userspace/snake/main.cpp

@@ -0,0 +1,242 @@
+#include <BAN/Vector.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <time.h>
+
+enum Direction
+{
+	None,
+	Unknown,
+	Left,
+	Right,
+	Up,
+	Down,
+};
+
+struct Point
+{
+	int x, y;
+	bool operator==(const Point& other) const { return x == other.x && y == other.y; }
+};
+
+bool				g_running		= true;
+Point				g_grid_size		= { 21, 21 };
+Direction			g_direction		= Direction::Up;
+Point				g_head			= { 10, 10 };
+int					g_tail_target	= 3;
+int					g_score			= 0;
+BAN::Vector<Point>	g_tail;
+Point				g_apple;
+
+Direction query_input()
+{
+	char c;
+	if (read(STDIN_FILENO, &c, 1) != 1)
+		return Direction::None;
+
+	switch (c)
+	{
+		case 'w': case 'W':
+			return Direction::Up;
+		case 'a': case 'A':
+			return Direction::Left;
+		case 's': case 'S':
+			return Direction::Down;
+		case 'd': case 'D':
+			return Direction::Right;
+		default:
+			return Direction::Unknown;
+	}
+}
+
+void set_grid_tile(Point point, const char* str)
+{
+	printf("\e[%d;%dH%s", (point.y + 1) + 1, (point.x + 1) * 2 + 1, str);
+}
+
+Point get_random_point()
+{
+	return { .x = rand() % g_grid_size.x, .y = rand() % g_grid_size.y };
+}
+
+void update_apple()
+{
+regenerate:
+	g_apple = get_random_point();
+	if (g_head == g_apple)
+		goto regenerate;
+	for (auto point : g_tail)
+		if (point == g_apple)
+			goto regenerate;
+	set_grid_tile(g_apple, "\e[31mO");
+}
+
+void setup_grid()
+{
+	// Move cursor to beginning and clear screen
+	printf("\e[H\e[J");
+
+	// Render top line
+	for (int x = 0; x < g_grid_size.x + 2; x++)
+		printf("# ");
+	putchar('\n');
+
+	// Render side lines
+	for (int y = 0; y < g_grid_size.y; y++)
+		printf("#\e[%dC#\n", g_grid_size.x * 2 + 1);
+
+	// Render Bottom line
+	for (int x = 0; x < g_grid_size.x + 2; x++)
+		printf("# ");
+	putchar('\n');
+
+	// Render snake head
+	set_grid_tile(g_head, "O");
+
+	// Generate and render apple
+	srand(time(0));
+	update_apple();
+
+	// Render score
+	printf("\e[%dH\e[mScore: %d", g_grid_size.y + 3, g_score);
+
+	fflush(stdout);
+}
+
+void update()
+{
+	auto input = Direction::None;
+	auto new_direction = Direction::None;
+	while ((input = query_input()) != Direction::None)
+	{
+		switch (input)
+		{
+			case Direction::Up:
+				if (g_direction != Direction::Down)
+					new_direction = Direction::Up;
+				break;
+			case Direction::Down:
+				if (g_direction != Direction::Up)
+					new_direction = Direction::Down;
+				break;
+			case Direction::Left:
+				if (g_direction != Direction::Right)
+					new_direction = Direction::Left;
+				break;
+			case Direction::Right:
+				if (g_direction != Direction::Left)
+					new_direction = Direction::Right;
+				break;
+		}
+	}
+
+	if (new_direction != g_direction && new_direction != Direction::None)
+		g_direction = new_direction;
+
+	auto old_head = g_head;
+	switch (g_direction)
+	{
+		case Direction::Up:
+			g_head.y--;
+			break;
+		case Direction::Down:
+			g_head.y++;
+			break;
+		case Direction::Left:
+			g_head.x--;
+			break;
+		case Direction::Right:
+			g_head.x++;
+			break;
+	}
+
+	if (g_head.x < 0 || g_head.y < 0 || g_head.x >= g_grid_size.x || g_head.y >= g_grid_size.y)
+	{
+		g_running = false;
+		return;
+	}
+
+	for (auto point : g_tail)
+	{
+		if (point == g_head)
+		{
+			g_running = false;
+			return;
+		}
+	}
+
+	if (g_head == g_apple)
+	{
+		g_tail_target++;
+		g_score++;
+		update_apple();
+		printf("\e[%dH\e[mScore: %d", g_grid_size.y + 3, g_score);
+	}
+
+	MUST(g_tail.insert(0, old_head));
+	if (g_tail.size() > g_tail_target)
+	{
+		set_grid_tile(g_tail.back(), " ");
+		g_tail.pop_back();
+	}
+
+	set_grid_tile(old_head, "\e[32mo");
+	set_grid_tile(g_head,   "\e[32mO");
+
+	fflush(stdout);
+}
+
+int main()
+{
+	// Make stdin non blocking
+	if (fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK))
+	{
+		perror("fcntl");
+		return 1;
+	}
+
+	// Set stdin mode to non-canonical
+	termios tcold, tcnew;
+	if (tcgetattr(STDIN_FILENO, &tcold) == -1)
+	{
+		perror("tcgetattr");
+		return 1;
+	}
+
+	tcnew = tcold;
+	tcnew.c_lflag &= ~(ECHO | ICANON);
+	if (tcsetattr(STDIN_FILENO, TCSANOW, &tcnew))
+	{
+		perror("tcsetattr");
+		return 1;
+	}
+
+	printf("\e[?25l");
+	setup_grid();
+
+	timespec delay;
+	delay.tv_sec = 0;
+	delay.tv_nsec = 100'000'000;
+
+	while (g_running)
+	{
+		nanosleep(&delay, nullptr);
+		update();
+	}
+
+	// Restore stdin mode
+	if (tcsetattr(STDIN_FILENO, TCSANOW, &tcold))
+	{
+		perror("tcsetattr");
+		return 1;
+	}
+
+	// Reset ansi state
+	printf("\e[m\e[?25h\e[%dH", g_grid_size.y + 4);
+
+	return 0;
+}