Output

Animating an object

In this example below, the 3D object is animated along a horizontal plane. The animation speed is independent of the frame rate.

The 3D object will move across the scene at a consistent speed on a range of different devices:

Animating an object along a forward vector

The patch group below moves an object along its forward vector at a consistent speed using the Delta Time and Rotate Vector patches.

The 3D object can be seen moving across the scene:

Scripting

Equivalent functionality can be achieved in a script with the deltaTimeMS property, which is exposed by the Time module

const Scene = require('Scene');
const Reactive = require('Reactive');
// Time module containing deltaTimeMS property
const Time = require('Time');


(async function () {

    // To access scene objects
    const [cube] = await Promise.all([
        Scene.root.findFirst('cube')
    ]);

    const vector = Reactive.vector(0, 0, -1);
    const rotatedVector = vector.rotate(cube.transform.rotation);
    const velocity = Time.deltaTimeMS.div(1000).mul(rotatedVector);
    cube.transform.position = cube.transform.position.history(1).frame(-1).add(velocity);

})();

Unlike the Delta Time patch which outputs the time value in seconds, the deltaTimeMS property returns a time value in milliseconds for consistency with the rest of the Spark API.