---
title: Abilities & interactions
product: Advanced Framework Pro
version: 1.0
engine: Unreal Engine 5.8
updated: 2026-10-05
canonical: https://docs.human-codeable.com/concepts/abilities.html
---

# Abilities & interactions

Everything interactive in the framework is built from four component base classes and one data struct. Understanding these five pieces is enough to read the rest of the codebase.

**Abilities act. Interactions are acted upon.** An ability lives on the player: on the pawn (`BPC_PawnAbility`), on a motion controller (`BPC_ControllerAbility`), or on an arbitrary actor (`BPC_ActorAbility`). An interaction (`BPC_Interaction`) lives on the object being manipulated. Abilities trace, poll input and decide what to do; interactions declare what may be done to them and respond.

**Capability is presence.** An object becomes grabbable by having `BPC_Interaction_Grip` attached, selectable by having `BPC_Interaction_Select`, and so on. There is no registration step and no central manager to update — adding the component is the whole opt-in.

**Vetoes are interfaces.** If an object needs conditional behaviour, it implements the matching interface (`Interface_Grip`, `Interface_Select`, `Interface_Gaze`) and returns an override flag alongside the answer. Not implementing the interface means "yes, always", so the common case stays free of boilerplate.

**Source Info carries identity.** Every interaction call receives an `ST_SourceInfo` describing the pawn that acted, the component that acted, and its identifier. A target therefore knows who touched it without ever referencing a pawn class, which is what keeps interactable actors reusable across VR, desktop and mobile.

![An ability acting on an interaction, carrying Source Info](../images/diagram_ability_interaction.svg?v=702773a6)

An ability acting on an interaction, carrying Source Info

## The four base classes

| Class | Lives on | Used for |
|---|---|---|
| `BPC_PawnAbility` | The pawn | Abilities that belong to the player as a whole: select, gaze, teleport, HUD, spatial UI |
| `BPC_ControllerAbility` | A motion controller actor | Abilities that belong to one hand: grip, laser, locomotion, hand UI |
| `BPC_ActorAbility` | Any actor | Abilities on non-player actors, such as overlap probes |
| `BPC_Interaction` | The target object | What may be done to this object |

## Reading an interaction stack

Take grip as the example. `BPC_PawnAbility_Grip` on the pawn coordinates; the per-hand `BPC_ControllerAbility_Hand_Grab` polls input and traces; `BPC_Interaction_Grip` on the target declares grippability, and its subclasses `_Pickup`, `_Latch`, `_Latch_Drag` and `_Latch_Physics` specialise the behaviour. `BPC_Socket_Grip` components mark where hands may attach, and `Interface_Grip` on the owning actor can veto.

Every other stack — select, gaze, overlap, teleport — follows the same shape.