Bob

Bob rises an entity above where it rests and back down, once every seconds. It applies as a difference from its last offset, so it rides on whatever else moves the entity, a kinematic body’s next pose included.

Its props are in BobProps.

On a body

On an entity with a kinematic body, Bob raises the body through its next pose, as setNextPose does, so it pushes what it meets and carries what stands on it. On a fixed or a dynamic body it throws in development, naming the entity, since a fixed body never moves and a dynamic one is the solver’s: make the body kinematic, as the example’s coin does.

Where it runs

The room and every page. On an entity the room streams, the room raises it, a kinematic body with it, and each page draws the pose the stream brings. On an entity only a page holds, that page raises it.

The example template’s coin turns with Spin and rises with Bob, on a kinematic body:

games/example/src/components/Coin.tsx

import {
    Bob,
    box,
    Entity,
    Pickup,
    type Position,
    RigidBodyType,
    sounds,
    Spin,
} from "@spawnite/engine";

/** One coin: it turns, bobs, and goes into the wallet of whoever reaches it,
 *  with a chime.
 *  Its body follows the bob, so the ball bounces off it where it is drawn. */
export interface CoinProps {
    position: Position;
}

export function Coin({ position }: CoinProps) {
    return (
        <Entity
            position={position}
            body={{ bodyType: RigidBodyType.Kinematic }}
            collider={{ shape: box({ size: [0.8, 0.1, 0.8] }) }}
        >
            <Spin speed={2} />
            <Bob height={0.2} />
            <Pickup reward={1} sound={sounds.pickup} />
            <mesh>
                <cylinderGeometry args={[0.4, 0.4, 0.1, 24]} />
                <meshStandardMaterial color="gold" />
            </mesh>
        </Entity>
    );
}