Collider2D
Realot Studio Collider2D component reference: fields, script API, behavior and examples.
#What it does
Physics collision shape and contact filtering. A Collider2D is also required for accurate pointer/touch hit tests.
#How to add and use Collider2D
Editor path: Select the target entity in the Hierarchy (left side) → look at the Inspector (right side) → click Add Component at the bottom of the Inspector → search for Collider2D → click the component row. The Add Component picker is a centered modal with a search box; it only lists components not already attached.
For components with a dedicated editor tool, the tool is opened or activated from the location described below. Do not assume that adding the component alone activates its editor; some systems require a separate window, panel, or viewport tool.
#Component setup & editor tools
- Select entity → Inspector → Add Component → Collider 2D. After adding it, edit Shape, dimensions, Offset, Trigger, Friction, Restitution, Density, Layer, and Mask in the Collider2D section. The viewport Collider gizmo shows the collision shape.
#What you should see after adding it
The component appears as its own section in the Inspector. Its serialized settings are listed in the Component data table below. If a field is conditional, it appears only when the relevant mode/type is selected. If a field is a runtime state field (for example grounded or resolved velocity), treat it as read-only diagnostic state unless the API reference explicitly documents it as writable.
#How to read the settings
For every setting below, the documentation distinguishes type, default, meaning, and tuning direction where behavior is known. When a value represents a direction, use the engine's coordinate convention documented in Coordinate system; do not substitute Unity/Godot conventions.
#Component data
| Field | Type | Purpose | Default |
|---|---|---|---|
shape | ColliderShape enum: Box | Circle | Capsule | Triangle | Box | Circle | Capsule | Triangle. | Box |
width | number | Box width. | 1 |
height | number | Box height. | 1 |
radius | number | Circle radius. | 0.5 |
capsuleHalfHeight | number | Capsule: a "stadium" shape (rectangle with semicircle caps) — matches Rapier's ColliderDesc.capsule(halfHeight, radius), whose principal axis is Y (i.e. | 0.5 |
capsuleRadius | number | Capsule radius. | 0.3 |
trianglePoints | array | Triangle: 3 points in the entity's LOCAL space (same space as offsetX/offsetY), user-editable via 3 draggable gizmo handles. | [{x:-0.5,y:0.5}, {x:0.5,y:0.5}, {x:0,y:-0.5}] |
offsetX | number | Local X offset. | 0 |
offsetY | number | Local Y offset. | 0 |
rotation | number | Collider-only rotation, in degrees, applied on top of the entity's own Transform.rotation. | 0 |
isTrigger | boolean | Trigger-only collider. | false |
isOneWayPlatform | boolean | One-way platform: solid only when the other body is landing on it from above; a body approaching from below or the side passes straight through, like a Mario/Metroidvania jump-through platform. | false |
oneWayDirection | OneWayDirection enum: Up | Down | Inspector field stored on this component. | Up |
friction | number | Surface friction. | 0.5 |
restitution | number | Bounciness. | 0 |
density | number | Density. | 1 |
layer | number | Collision layer/mask — inspired by Unity's physics layer matrix. | 0 |
mask | value | Layers this collider can interact with. | 0xFFFF |
#Tuning behavior
These are the practical direction-of-change rules for the most important controls on this component.
| Setting | What changing it does |
|---|---|
restitution | 0 behaves as non-bouncy; increasing it produces more bounce. Keep in a physically sensible range for predictable results. |
friction | Higher values resist sliding more strongly. Lower values let contacts slide more easily. |
density | Affects mass/inertia when the physics world builds the body from colliders; it is not a direct “heaviness” multiplier on gravity. |
offsetX / offsetY | Moves the collider relative to the entity’s pivot; positive X/right and positive Y/down in world-space convention. |
#Script API
| Member | Kind | Description |
|---|---|---|
capsuleHalfHeight | Property (read-only) | Capsule half-height. |
capsuleRadius | Property (read-only) | Capsule radius. |
density | Property (read-only) | Density. |
friction | Property (read-only) | Friction. |
height | Property (read-only) | Box height. |
isColliding(other) | Method | The `this.collider` sub-object exposed to user scripts. |
isOneWayPlatform | Property (read-only) | One-way platform flag. |
isTrigger | Property (read/write) | Trigger-only collider. |
layer | Property (read-only) | Layer index 0-15. |
mask | Property (read-only) | 16-bit interaction mask. |
offset | Property (read-only) | {x,y} collider offset. |
oneWayDirection | Property (read/write) | The `this.collider` sub-object exposed to user scripts. |
radius | Property (read-only) | Circle radius. |
restitution | Property (read-only) | Restitution. |
rotation | Property (read/write) | The `this.collider` sub-object exposed to user scripts. |
shape | Property (read-only) | Box | Circle | Capsule | Triangle. |
width | Property (read-only) | Box width. |
#Notes & behavior
- Collision layers use 16 membership layers (0-15). The mask determines which layers the collider can interact with.
- One-way platforms are intended to block from one side while allowing traversal from the non-blocking side.
#Examples
this.collider.isTrigger = true;this.collider.layer = 2;this.collider.mask = 0xFFFF;