Mover Context

GS_MoverContextComponent is the central state store for all movement on a unit. It sits between the input layer and the mover/grounder layer, holds all shared movement data, owns the mode-switching logic, and manages the active movement profile.

Movers and Grounders never communicate directly — they all read from and write to the MoverContext.

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

Contents

• Input Transformation Pipeline
• Mode Switching
• Context States
• Movement Profile Management
• Editor-Exposed Fields
• API Reference
• See Also

Input Transformation Pipeline

Raw input from reactor components arrives as a Vector2 (rawMoveInput). The MoverContext applies two sequential transformations each time input changes.

Step 1 — ModifyInputAxis() — Camera-Relative

For a player unit (detected by “Player” tag): fetches the active camera’s world transform, flattens its forward and right vectors to the XY plane, then computes:

modifiedMoveInput = camForward * rawInput.Y + camRight * rawInput.X

For AI units (or when inputOverride = true): uses world cardinal axes (Y=forward, X=right).

Step 2 — GroundInputAxis() — Ground-Projected

Projects modifiedMoveInput onto the ground plane using the current groundNormal:

groundedMoveInput = modifiedMoveInput - groundNormal * dot(modifiedMoveInput, groundNormal)

Direction is then normalized and the original magnitude is restored. Movers use groundedMoveInput so movement always follows the surface contour, even on slopes.

Both steps run automatically whenever SetMoveInputAxis is called and again whenever SetGroundNormal is called (ground changed under a moving unit).

Mode Switching

The MoverContext maintains three independent mode strings, each with a current and last value:

ChangeMovementMode("Free") updates the string and broadcasts MoverContextNotificationBus::MovementModeChanged("Free"). Each Mover and Grounder component checks whether its own named mode matches the broadcast and activates or deactivates itself accordingly.

RevertToLastMovementMode() swaps current and last — enabling one-step undo (e.g., return from “Slide” to whatever was active before).

Context States

A generic key-value store for runtime state flags used by movers and grounders:

AZStd::unordered_map<AZStd::string, AZ::u32> contextStates

SetContextState(name, value) writes and broadcasts MoverContextNotificationBus::ContextStateChanged.

Known state keys:

Movement Profile Management

The MoverContext selects the active GS_UnitMovementProfile* by priority:

1. Influence list — AddMovementProfile(influencer, profile*) is called by MovementInfluenceFieldComponent when the unit enters a trigger volume. Multiple fields stack additively by priority via MovementInfluenceRequestBus::GetPriority.
2. Global fallback — if influenceList is empty and allowGlobalInfluence is true, checks GlobalMovementRequestBus::GetGlobalMovementProfile.
3. Default profile — the asset-configured defaultMoveProfile on the component.

When the profile changes, MoverContextNotificationBus::MovementProfileChanged(profile*) is broadcast. Movers update their cached activeProfile pointer.

Standby behavior:

• UnitEnteringStandby → clears the influence list, broadcasts empty mode names (disables all movers/grounders)
• UnitExitingStandby → re-evaluates profile priority, re-broadcasts current mode names to re-enable the correct movers

Editor-Exposed Fields

API Reference

Request Bus: MoverContextRequestBus

Commands sent to a specific unit’s MoverContext. ById bus — addressed by unit entity ID.

Input Axis:

Ground State:

Context States:

Mode Switching:

Profile Management:

Notification Bus: MoverContextNotificationBus

Events broadcast by the MoverContext. ById bus — addressed by unit entity ID. Movers and Grounders subscribe to this.

Virtual Methods

Override these when extending the MoverContext.

Script Canvas Examples

Changing movement mode:

Reverting to the previous movement mode:

Setting a context state flag:

See Also

• Movers — Mover components that read from the MoverContext
• Grounders — Grounder components that write ground state to the MoverContext
• Movement — Movement system overview
• Input Data — The input pipeline that feeds SetMoveInputAxis

Get GS_Unit

GS_Unit — Explore this gem on the product page and add it to your project.