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Tween Chaining

Description

A sequence of tweens can be chained so that when one tween finishes, another tween begins.

This is useful for creating extended animation sequences.

See the chainTweens function in the example script that demonstrates a repeating sequence of tweens that modify an objects transforms.

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Example Script

./src/client/client.ts

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import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls'
import Stats from 'three/examples/jsm/libs/stats.module'
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader'
import TWEEN from '@tweenjs/tween.js'

const scene = new THREE.Scene()
scene.add(new THREE.AxesHelper(5))

const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
)
camera.position.set(-0.6, 0.45, 2)

const renderer = new THREE.WebGLRenderer()
//renderer.physicallyCorrectLights = true //deprecated
renderer.useLegacyLights = false //use this instead of setting physicallyCorrectLights=true property
renderer.shadowMap.enabled = true
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

const controls = new OrbitControls(camera, renderer.domElement)
controls.enableDamping = true

const raycaster = new THREE.Raycaster()
const sceneMeshes: THREE.Object3D[] = []

let monkey: THREE.Object3D

const loader = new GLTFLoader()
loader.load(
    'models/monkey.glb',
    function (gltf) {
        gltf.scene.traverse(function (child) {
            if ((child as THREE.Mesh).isMesh) {
                const m = child as THREE.Mesh
                if (m.name === 'Suzanne') {
                    m.castShadow = true
                    monkey = m
                } else {
                    // floor
                    m.receiveShadow = true
                }
                sceneMeshes.push(m)
            }
            if ((child as THREE.Light).isLight) {
                const l = child as THREE.SpotLight
                l.castShadow = true
                l.shadow.bias = -0.001
            }
        })
        scene.add(gltf.scene)

        chainTweens()
    },
    (xhr) => {
        console.log((xhr.loaded / xhr.total) * 100 + '% loaded')
    },
    (error) => {
        console.log(error)
    }
)

function chainTweens() {
    // Demonstrating a repeating sequence of tweens.
    const changePositionZ = new TWEEN.Tween(monkey.position).to({ z: -2 }, 2000) // 2 seconds
    const rotateY = new TWEEN.Tween(monkey.rotation).to(
        { y: Math.PI * 2 },
        2000
    )
    const scaleXZ = new TWEEN.Tween(monkey.scale).to({ x: 2, z: 0.5 }, 2000)
    const rotateZ = new TWEEN.Tween(monkey.rotation).to(
        { z: Math.PI * 2 },
        2000
    )
    const resetScaleXZ = new TWEEN.Tween(monkey.scale).to({ x: 1, z: 1 }, 2000)
    const resetPositionZ = new TWEEN.Tween(monkey.position).to({ z: 0 }, 2000)
    const rotateX = new TWEEN.Tween(monkey.rotation).to(
        { x: Math.PI * 2 },
        2000
    )
    const resetRotations = new TWEEN.Tween(monkey.rotation).to(
        { x: 0, y: 0, z: 0 },
        0
    ) // 0 seconds results in an instant tween

    changePositionZ.chain(rotateY)
    rotateY.chain(scaleXZ)
    scaleXZ.chain(rotateZ)
    rotateZ.chain(resetScaleXZ)
    resetScaleXZ.chain(resetPositionZ)
    resetPositionZ.chain(rotateX)
    rotateX.chain(resetRotations)
    resetRotations.chain(changePositionZ) // begin the loop again

    changePositionZ.start()
}

const mouse = new THREE.Vector2()
function onDoubleClick(event: MouseEvent) {
    mouse.set(
        (event.clientX / renderer.domElement.clientWidth) * 2 - 1,
        -(event.clientY / renderer.domElement.clientHeight) * 2 + 1
    )
    raycaster.setFromCamera(mouse, camera)

    const intersects = raycaster.intersectObjects(sceneMeshes, false)

    if (intersects.length > 0) {
        const p = intersects[0].point
        new TWEEN.Tween(controls.target)
            .to(
                {
                    x: p.x,
                    y: p.y,
                    z: p.z,
                },
                500
            )
            .easing(TWEEN.Easing.Cubic.Out)
            .start()
    }
}
renderer.domElement.addEventListener('dblclick', onDoubleClick, false)

function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight
    camera.updateProjectionMatrix()
    renderer.setSize(window.innerWidth, window.innerHeight)
    render()
}
window.addEventListener('resize', onWindowResize, false)

const stats = new Stats()
document.body.appendChild(stats.dom)

function animate() {
    requestAnimationFrame(animate)

    controls.update()

    TWEEN.update()

    render()

    stats.update()
}

function render() {
    renderer.render(scene, camera)
}

animate()

Glowing Warmness (Shows Many Chains)

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