Input Reactor

Input reactor components sit on the unit entity and listen to InputDataNotificationBus. They are the unit-side response layer that turns stored input state into game actions — movement vectors, ability triggers, UI navigation, etc.

For usage guides and setup examples, see The Basics: GS_Unit.

Contents

• How It Works
• Base Classes
• Concrete Reactors
• API Reference
• Extension Guide
• See Also

How It Works

Each reactor declares which event names it cares about (inputReactEvents). When InputDataNotificationBus::InputStateChanged fires, the reactor compares the incoming stateName against its list. If it matches, it compares the new value against the previously stored value and calls the correct virtual method:

• 0 → non-zero → HandlePressed
• non-zero → non-zero → HandleHeld
• non-zero → 0 → HandleReleased
• any change → HandleAxisChanged (axis variant only)

Reactors store lastInputValues per event name to track zero-crossings between frames.

Base Classes

GS_InputReactorComponent

Base class for discrete button/key input. Extend this to react to named input events with press, hold, and release semantics.

Virtual methods to override:

Fields:

GS_InputAxisReactorComponent

Base class for analogue axis input. Extend this for joystick, trigger, or any continuous value that should not use pressed/held/released semantics.

Virtual methods to override:

Concrete Reactors

KeyboardMovement_InputReactorComponent

Converts four discrete directional key events into a 2D movement axis. Maps moveUp/moveDown/moveLeft/moveRight to +1/-1 contributions on the X and Y axes. On any key press or release, recomputes the combined axis and calls MoverContextRequestBus::SetMoveInputAxis("x"/"y", value) on the unit.

Internal accumulation fields:

JoyAxisMovement_AxisReactorComponent

Directly maps two joystick axis event names to the Mover Context X and Y movement axes. Calls MoverContextRequestBus::SetMoveInputAxis("x"/"y", value) directly from HandleAxisChanged.

API Reference

Reactors themselves do not expose a request bus. They consume InputDataNotificationBus and produce calls to MoverContextRequestBus or other action buses.

InputDataNotificationBus (consumed)

MoverContextRequestBus (produced by movement reactors)

Extension Guide

Use the InputReactor ClassWizard template to generate a new input reactor with boilerplate already in place — see GS_Unit Templates.

Create custom reactor components by extending GS_InputReactorComponent or GS_InputAxisReactorComponent.

#pragma once
#include <GS_Unit/InputData/GS_InputReactorComponent.h>

namespace MyProject
{
    class AbilityInputReactor : public GS_Unit::GS_InputReactorComponent
    {
    public:
        AZ_COMPONENT_DECL(AbilityInputReactor);
        static void Reflect(AZ::ReflectContext* context);

    protected:
        void HandlePressed(const AZStd::string& stateName) override;
        void HandleReleased(const AZStd::string& stateName) override;
    };
}

In Reflect(), add the event names you want to listen to:

// In your component's activation or reflection, populate inputReactEvents:
inputReactEvents.push_back("ability_primary");
inputReactEvents.push_back("ability_secondary");

See Also

• Input Data — The full input pipeline overview
• Player Input Reader — Controller-side input reading
• Mover Context — Receives axis input from reactor components

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