Using Area2D

    Note

    This document assumes you’re familiar with Godot’s various physics bodies. Please read first.

    An Area2D defines a region of 2D space. In this space you can detect other nodes overlapping, entering, and exiting. Areas also allow for overriding local physics properties. We’ll explore each of these functions below.

    Areas have many properties you can use to customize their behavior.

    The first eight properties are used to configure the area’s physics override behavior. We’ll look at how to use those in the section below.

    Monitoring and Monitorable are used to enable and disable the area.

    The “Collision” section is where you configure the area’s collision layer(s) and mask(s).

    The “Audio Bus” section allows you to override audio in the area, for example to apply an audio effect when the player moves through.

    Note that Area2D extends , so it also provides properties inherited from that class, such as .

    Perhaps the most common use of Area2D nodes is for contact and overlap detection. When you need to know that two objects have touched, but don’t need physical collision, you can use an area to notify you of the contact.

    For example, let’s say we’re making a coin for the player to pick up. The coin is not a solid object - the player can’t stand on it or push it - we just want it to disappear when the player touches it.

    ../../_images/area2d_coin_nodes.png

    To detect the overlap, we’ll connect the appropriate signal on the Area2d. Which signal to use depends on the player’s node type. If the player is another area, use area_entered. However, let’s assume our player is a KinematicBody2D (and therefore a CollisionObject2D type), so we’ll connect the signal.

    Note

    If you’re not familiar with using signals, see for an introduction.

    GDScript   C#

    1. public class Coin : Area2D
    4.     {
    5.         QueueFree();
    6.     }

    Now our player can collect the coins!

    Some other usage examples:

    • Areas are great for bullets and other projectiles that hit and deal damage, but don’t need any other physics such as bouncing.

    • Use a large circular area around an enemy to define its “detect” radius. When the player is outside the area, the enemy can’t “see” it.

    See the Your first 2D game for an example of using Area2D in a game.

    The second major use for area nodes is to alter physics. By default, the area won’t do this, but you can enable this with the Space Override property. When areas overlap, they are processed in Priority order (higher priority areas are processed first). There are four options for override:

    • Replace - The area replaces physics properties, and lower priority areas are ignored.

    • Combine-Replace - The area adds its gravity/damping values to whatever has been calculated so far (in priority order), ignoring any lower priority areas.

    • Replace-Combine - The area replaces any gravity/damping calculated so far, but keeps calculating the rest of the areas.

    Using these properties, you can create very complex behavior with multiple overlapping areas.

    The physics properties that can be overridden are:

    • Gravity - Gravity’s strength inside the area.

    • Gravity Vec - Gravity’s direction. This vector does not need to be normalized.

    • Linear Damp - How quickly objects stop moving - linear velocity lost per second.

    • Angular Damp - How quickly objects stop spinning - angular velocity lost per second.

    The Gravity Point property allows you to create an “attractor”. Gravity in the area will be calculated towards a point, given by the Gravity Vec property. Values are relative to the Area2D, so for example using (0, 0) will attract objects to the center of the area.

    Examples

    The example project attached below has three areas demonstrating physics override.