# Area2D

A trigger zone that fires body_entered / body_exited.

```{raw} html
<a class="example-run-button" href="../demos/features_2d_area2d.html">▶ Run in browser</a>

```

**Tags:** `2d` `physics` `area` `trigger` `signals`

A PhysicsBody2D shuttles left and right across the screen and repeatedly
passes through a stationary Area2D sensor. The Area2D emits body_entered when
the walker overlaps it and body_exited when it leaves; the demo recolours the
zone while occupied and counts total entries.


## What it demonstrates
- Area2D as a broadphase sensor zone with a CollisionShape2D child (rectangle).
- Connecting to the body_entered / body_exited signals (payload is the body).
- A PhysicsBody2D inside a PhysicsRoot2D driven by velocity each fixed step.
- Reacting to overlap state: recolour the zone, count entries, live HUD.

Controls:
  ESC - Quit

## Source

```{literalinclude} ../../examples/features/2d/area2d.py
:language: python
:linenos:
```