Vehicles

Creates a native Jolt Physics 5.6 wheeled vehicle around an ordinary Dynamic JoltBody chassis.

JoltVehicle owns a VehicleConstraint, WheeledVehicleController and virtual wheels. Jolt solves suspension, tyre forces, drivetrain and contacts inside jolt_update(); GameMaker owns input and rendering.

What a vehicle contains#

• One existing Dynamic, non-sensor JoltBody used as the chassis.
• Two to thirty-two virtual wheels. Wheels are not separate rigid bodies.
• Per-wheel suspension, steering, drive and brake configuration.
• A native engine, transmission, one or more differentials and optional anti-roll bars.
• A wheel collision tester that finds ground through the chassis collision layer.

Coordinate convention#

Recommended workflow#

var chassis = jolt_box_create_dynamic(...);
var car = jolt_vehicle(chassis, options);
car.add_wheel(...);
car.add_wheel(...);
car.build();

// Step event
car.set_inputs(throttle, steering, brake, handbrake);
jolt_update();

Important ownership rules#

• The vehicle reuses its chassis; it does not own the GameMaker variable or render model.
• Vehicle configuration is a draft until build() and becomes immutable after a successful build.
• Destroying the chassis invalidates its dependent vehicle. jolt_stop() destroys vehicles before bodies and the world.
• Use is_valid() before retaining a vehicle across uncertain lifetime boundaries.