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CH Amrut Prasad Patro
CH Amrut Prasad Patro

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Terminal Snake in Rust: A Systems Programming Journey

#rust #gamedev #systems #programming

Building Terminal Snake in Rust: A Systems Programming Journey

After completing The Rust Book through Chapter 8, I decided to build something practical to internalize ownership, borrowing, and structs. The result: a fully-functional terminal Snake game using crossterm.

Architecture Overview

The game is built around four core structs:

#[derive(Clone, Copy, PartialEq)]
struct Position { x: u16, y: u16 }

enum Direction { Up, Down, Right, Left }

struct Snake {
    body: Vec<Position>,
    direction: Direction,
}

struct Game {
    snake: Snake,
    food: Position,
    running: bool,
    score: i32
}
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Key Implementation Patterns

1. Non-Blocking Input Handling

The game loop runs at 80ms intervals, but we need to check for keyboard input without blocking:

if event::poll(Duration::from_millis(0))? {
    if let Event::Key(key_event) = event::read()? {
        // Process arrow keys
    }
}
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This pattern is crucial for game loops where the snake moves continuously even without input.

2. Snake Movement & Growth

Movement is implemented by inserting a new head and removing the tail:

snake.body.insert(0, new_head_position);
snake.body.pop(); // Remove tail (unless growing)
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When food is eaten, we skip the pop(), naturally growing the snake.

3. Efficient Rendering with Buffering

Instead of flushing every draw command (O(n) terminal updates), we batch them:

for pos in &snake.body {
    stdout.queue(cursor::MoveTo(pos.x, pos.y))?
          .queue(style::PrintStyledContent("██".yellow()))?;
}
stdout.flush()?; // Single flush for entire frame
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This eliminates flicker and improves performance.

4. Collision Detection Order Matters

A subtle bug: checking body collision after eating food caused false positives. The fix:

check_wall_collision()?;
check_body_collision()?;  // ← Check BEFORE eating food
check_food_collision()?;
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What I Learned

Ownership & Borrowing in Practice:

  • Passing &mut Game vs &Game based on whether functions modify state
  • Using .clone() strategically for Position (cheap Copy type)
  • Managing mutable references across function boundaries

Pattern Matching Power:
Direction changes with validation (can't reverse into yourself):

direction = match key_event.code {
    KeyCode::Up if !matches!(snake.direction, Direction::Down) => Direction::Up,
    // ...
}
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Memory Safety:
Zero unsafe code, no memory leaks, no buffer overflows. Rust's compiler enforced correct resource management throughout.

Technical Stack

  • crossterm - Cross-platform terminal manipulation
  • rand - Random food spawning
  • Raw mode terminal with alternate screen buffers

What's Next?

This project was a stepping stone toward my goal of becoming an ML Systems Engineer. Next up: building production Rust backends with Axum for async ML inference serving.

🔗 GitHub: https://github.com/Halloloid/RustySnake

What game would you build to learn a new language? Drop your thoughts below!

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