# Pong

[Play Demo](/demos/game_pong.html)

Build a classic Pong game demonstrating input actions, collision detection,
signals, and game state management.

## What You Will Learn

- **Input actions** -- Bind keys to named actions with `InputMap.add_action()`
- **Input.get_strength()** -- Read analogue input strength for smooth movement
- **Signals** -- Decouple game events (the ball emits `scored` when it passes a paddle)
- **Collision** -- Manual AABB overlap for paddle-ball bouncing
- **Game state** -- Track and display scores

## Controls

| Key | Action |
|-----|--------|
| W / S | Left paddle up / down |
| Up / Down | Right paddle up / down |

## How It Works

Three node types compose the game:

- **Paddle** reads two input actions (up/down) and clamps position to the screen
- **Ball** moves at a velocity, bounces off top/bottom edges, and emits a
  `scored` signal when it exits left or right
- **PongGame** (root) creates paddles and ball in `ready()`, connects the
  `scored` signal to update the score, and handles paddle-ball collision in
  `process()` by reflecting the ball's velocity based on where it hits the paddle

Input actions are registered in `__main__` via `InputMap.add_action()`, mapping
physical keys (`Key.W`, `Key.S`, `Key.UP`, `Key.DOWN`) to named actions that
the paddle nodes query each frame.

## Source Code

```{literalinclude} ../../packages/graphics/examples/game_pong.py
:language: python
:linenos:
```