2D Physics

2D Physics

Unity features a complete 2D physics simulation system that is separate from its 3D counterpart. All 2D physics classes and components end with a 2D suffix.

Rigidbody 2D

The Rigidbody 2D component puts the object under 2D physics control.

• Body Type:
• Dynamic: Affected by gravity and forces. Collides with all types. Used for characters and debris.
• Kinematic: Immune to forces/gravity. Moved manually via velocity or script. Collides only with Dynamic. Used for moving obstacles.
• Static: Position is fixed. Cannot be moved by physics. Used for ground and walls.

Colliders 2D

2D Colliders define physical collision boundaries:

• Box Collider 2D: Rectangular.
• Circle Collider 2D: Spherical boundary.
• Capsule Collider 2D: Capsule boundary.
• Polygon Collider 2D: Custom multi-sided shape (more expensive but accurate).
• Edge Collider 2D: A line or path of points (perfect for curved ground or slopes).

Physics Material 2D

A Physics Material 2D defines surface behavior:

• Friction: resistance to sliding.
• Bounciness: elasticity.

2D Physics Joint Components

Joints connect Rigidbody 2D components together:

• Hinge Joint 2D: Rotates around a pivot point (like a pendulum or swinging door).
• Distance Joint 2D: Keeps two objects at a fixed distance from each other.
• Slider Joint 2D: Restricts movement to a single axis (like a sliding drawer).

TL;DR

• All 2D physics components use the '2D' suffix (e.g. Rigidbody 2D).
• Body Types: Dynamic (forces), Kinematic (controlled), Static (fixed).
• Polygon and Edge Colliders support non-standard 2D shapes.
• 2D Joints connect rigidbodies with physical constraints.