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Hemisphere Light

Video Lecture

Hemisphere Light

Description

Note

Since Three r155, the default of WebGLRenderer.useLegacyLights was changed from true to false and will also be deprecated in r165. This means that intensity may need to be changed when using various types of lights if you want them to match your previous versions of Threejs. In simplest terms, the intensities for ambient, hemisphere, directional, spot lights and light maps can be restored by multiplying PI with the existing light intensity values.

E.g., if your intensity was 2, use

new THREE.DirectionalLight(0xffffff, Math.PI * 2)

The Threejs Hemisphere light is very like a directional light but also with settings to project the light in the reverse direction. I also demonstrate the Hemisphere light helper object.

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Lesson 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 { GUI } from 'dat.gui'

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

const light = new THREE.HemisphereLight(0xffffff, 0xffffff, Math.PI)
scene.add(light)

const helper = new THREE.HemisphereLightHelper(light, 5)
scene.add(helper)

const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
)
camera.position.z = 7

const renderer = new THREE.WebGLRenderer()
renderer.setSize(window.innerWidth, window.innerHeight)
document.body.appendChild(renderer.domElement)

new OrbitControls(camera, renderer.domElement)

// const planeGeometry = new THREE.PlaneGeometry(100, 10)
// const plane = new THREE.Mesh(planeGeometry, new THREE.MeshPhongMaterial())
// plane.rotateX(-Math.PI / 2)
// //plane.position.y = -1.75
// scene.add(plane)

const torusGeometry = [
    new THREE.TorusGeometry(),
    new THREE.TorusGeometry(),
    new THREE.TorusGeometry(),
    new THREE.TorusGeometry(),
    new THREE.TorusGeometry(),
]

const material = [
    new THREE.MeshBasicMaterial(),
    new THREE.MeshLambertMaterial(),
    new THREE.MeshPhongMaterial(),
    new THREE.MeshPhysicalMaterial({}),
    new THREE.MeshToonMaterial(),
]

const torus = [
    new THREE.Mesh(torusGeometry[0], material[0]),
    new THREE.Mesh(torusGeometry[1], material[1]),
    new THREE.Mesh(torusGeometry[2], material[2]),
    new THREE.Mesh(torusGeometry[3], material[3]),
    new THREE.Mesh(torusGeometry[4], material[4]),
]

const texture = new THREE.TextureLoader().load('img/grid.png')
material[0].map = texture
material[1].map = texture
material[2].map = texture
material[3].map = texture
material[4].map = texture

torus[0].position.x = -8
torus[1].position.x = -4
torus[2].position.x = 0
torus[3].position.x = 4
torus[4].position.x = 8

scene.add(torus[0])
scene.add(torus[1])
scene.add(torus[2])
scene.add(torus[3])
scene.add(torus[4])

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

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

const data = {
    color: light.color.getHex(),
    groundColor: light.groundColor.getHex(),
    mapsEnabled: true,
}

const gui = new GUI()
const lightFolder = gui.addFolder('THREE.Light')
lightFolder.addColor(data, 'color').onChange(() => {
    light.color.setHex(Number(data.color.toString().replace('#', '0x')))
})
lightFolder.add(light, 'intensity', 0, Math.PI * 2, 0.01)
lightFolder.open()

const hemisphereLightFolder = gui.addFolder('THREE.HemisphereLight')
hemisphereLightFolder.addColor(data, 'groundColor').onChange(() => {
    light.groundColor.setHex(
        Number(data.groundColor.toString().replace('#', '0x'))
    )
})

hemisphereLightFolder.add(light.position, 'x', -100, 100, 0.01)
hemisphereLightFolder.add(light.position, 'y', -100, 100, 0.01)
hemisphereLightFolder.add(light.position, 'z', -100, 100, 0.01)
hemisphereLightFolder.open()

const meshesFolder = gui.addFolder('Meshes')
meshesFolder.add(data, 'mapsEnabled').onChange(() => {
    material.forEach((m) => {
        if (data.mapsEnabled) {
            m.map = texture
        } else {
            m.map = null
        }
        m.needsUpdate = true
    })
})

function animate() {
    requestAnimationFrame(animate)

    //helper.update()

    torus.forEach((t) => {
        t.rotation.y += 0.01
    })

    render()

    stats.update()
}

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

animate()

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