PhysX Vehicle scripting and control

Address every public vehicle bus with the chassis entity id. Control and state buses are reflected to BehaviorContext (Lua / Script Canvas category PhysX Vehicle). Notification events are C++-only in the shipped Gem.

Who writes input

PhysX Vehicle Drive ──┐
Lua / Script Canvas ──┼──► VehicleControlRequestBus ──► Chassis solver
C++ / AI ──┘

Use one owner for throttle / steer / brake each frame. If Drive and a script both write the control bus, the last writer wins.

VehicleControlRequestBus

C++:

#include <PhysXVehicle/VehicleControlBus.h>

PhysXVehicle::VehicleControlRequestBus::Event(
 chassisEntityId, &PhysXVehicle::VehicleControlRequests::SetGear, 1);
PhysXVehicle::VehicleControlRequestBus::Event(
 chassisEntityId, &PhysXVehicle::VehicleControlRequests::SetThrottle, 1.0f);
PhysXVehicle::VehicleControlRequestBus::Event(
 chassisEntityId, &PhysXVehicle::VehicleControlRequests::SetSteer, -0.25f);

Lua (BehaviorContext):

VehicleControlRequestBus.Event.SetGear(self.entityId, 1)
VehicleControlRequestBus.Event.SetThrottle(self.entityId, 1.0)
VehicleControlRequestBus.Event.SetBrake(self.entityId, 0.0)
VehicleControlRequestBus.Event.SetSteer(self.entityId, 0.0)
VehicleControlRequestBus.Event.SetHandbrake(self.entityId, false)

Tracked differential:

PhysXVehicle::VehicleControlRequestBus::Event(
 chassisEntityId, &PhysXVehicle::VehicleControlRequests::SetTrackThrottle,
 leftThrottle, rightThrottle);

VehicleStateRequestBus

#include <PhysXVehicle/VehicleStateBus.h>

float speed = 0.0f;
PhysXVehicle::VehicleStateRequestBus::EventResult(
 speed, chassisEntityId, &PhysXVehicle::VehicleStateRequests::GetSpeed);

local speed = VehicleStateRequestBus.Event.GetSpeed(self.entityId)
local rpm = VehicleStateRequestBus.Event.GetEngineRpm(self.entityId)
local gear = VehicleStateRequestBus.Event.GetCurrentGear(self.entityId)

VehicleNotificationBus (C++ only)

These handlers are not reflected to BehaviorContext. Subscribe from C++ with VehicleNotificationBus::Handler on the chassis entity. For scripted reactions, poll state on tick or bridge through your own gameplay component.

Sample Lua driver

Gems/PhysXVehicle/Assets/Scripts/VehicleDriveExample.lua:

• Attach a Lua Script component to the chassis entity.
• Maps StartingPointInput (or Input Bindings) events:
• vehicle_throttle analog [0, 1]
• vehicle_brake analog [0, 1]
• vehicle_steer analog [-1, 1]
• vehicle_handbrake digital
• Calls SetGear(1) on activate and optionally logs speed / RPM / gear each second.

Disable PhysX Vehicle Drive when using this script so inputs do not fight.

Script Canvas

Look for EBus nodes under category PhysX Vehicle:

• Request nodes for each Set* / Get* on Control and State.
• Wire entity id pins to the chassis entity.

There are no Script Canvas event nodes for VehicleNotificationBus in the shipped Gem.

AI and gameplay

Typical pattern:

1. Omit Drive (or set Enabled = false).
2. Each AI tick (or decision), write throttle / steer / brake / gear (or SetTrackThrottle).
3. Read GetSpeed / grounded flags for decisions.
4. Optionally sync track UV from travel distances in a visual component.

Configuration structs are not exposed as a live script API—author them in the editor / Prefab.

Next steps

• Debugging — confirm forces when script input seems ignored.
• Reference — include paths and cheat sheet.
• Tracked vehicles — differential control details.