Three.js - Spotlight

Quiz

It is another kind of light that comes from a specific direction in the shape of the cone.

distance − Maximum range of the light. Default is 0 (no limit).
angle − Maximum angle of light dispersion from its direction whose upper bound is Math.PI/2.
penumbra − Percent of the spotlight cone attenuates due to penumbra. It takes values between zero and 1. Default is 0.
decay − The amount the light dims along with the distance of the light.

const light = new THREE.SpotLight(color, intensity)
light.position.set(1, 10, 10)
light.castShadow = true
light.shadow.camera.near = 5
light.shadow.camera.far = 400
light.shadow.camera.fov = 30

The shadow.camera.near, shadow.camera.far, and shadow.camera.fov properties define the area where shadows can appear.

Check out the following example.

Example

spotlight.html

<!DOCTYPE html>
<html lang="en">
   <head>
      <meta charset="UTF-8" />
      <meta http-equiv="X-UA-Compatible" content="ie=edge" />
      <meta name="viewport" content="width=device-width, initial-scale=1.0" />
      <title>Three.js - SpotLight</title>
      <style>
         * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: -applesystem, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu,
               Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
         }
         html,
         body {
            height: 100vh;
            width: 100vw;
         }
         #threejs-container {
            position: block;
            width: 100%;
            height: 100%;
         }
      </style>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js"></script>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/dat-gui/0.7.7/dat.gui.js"></script>
      </head>
   <body>
   <div id="container"></div>
      <script type="module">
         // Adding spotlight in Three.js
         // You can control the properties of light using the GUI
         // You can see the position and the cone of light in this example

         // GUI
         const gui = new dat.GUI()
         // sizes
         const width = window.innerWidth
         const height = window.innerHeight
         // scene
         const scene = new THREE.Scene()
         scene.background = new THREE.Color(0x262626)
         console.log(scene.children)
         // camera
         const camera = new THREE.PerspectiveCamera(60, width / height, 0.1, 1000)
         camera.position.set(0, 0, 10)
         const camFolder = gui.addFolder('Camera')
         camFolder.add(camera.position, 'z', 10, 80, 1)
         camFolder.open()
         // lights
         const ambientLight = new THREE.AmbientLight(0xffffff, 0.5)
         scene.add(ambientLight)
         const light = new THREE.SpotLight()
         light.position.set(0, 5, 0)
         // for shadow
         light.castShadow = true
         light.shadow.mapSize.width = 1024
         light.shadow.mapSize.height = 1024
         light.shadow.camera.near = 0.5
         light.shadow.camera.far = 100
         scene.add(light)
         const helper = new THREE.SpotLightHelper(light)
         scene.add(helper)
         // light controls
         const lightColor = {
            color: light.color.getHex()
         }
         const lightFolder = gui.addFolder('Light')
         lightFolder.addColor(lightColor, 'color').onChange(() => {
         light.color.set(lightColor.color)
         })
         lightFolder.add(light, 'intensity', 0, 1, 0.01)
         lightFolder.open()
         const spotLightFolder = gui.addFolder('SpotLight')
         spotLightFolder.add(light, 'distance', 0, 100, 0.01)
         spotLightFolder.add(light, 'decay', 0, 4, 0.1)
         spotLightFolder.add(light, 'angle', 0, 1, 0.1)
         spotLightFolder.add(light, 'penumbra', 0, 1, 0.1)
         spotLightFolder.add(light.position, 'x', -50, 50, 1)
         spotLightFolder.add(light.position, 'y', -50, 50, 1)
         spotLightFolder.add(light.position, 'z', -50, 50, 1)
         spotLightFolder.open()
         // plane
         const planeGeometry = new THREE.PlaneGeometry(100, 100)
         const plane = new THREE.Mesh(planeGeometry, new THREE.MeshPhongMateria
         l({ color: 0xffffff }))
         plane.rotateX(-Math.PI / 2)
         plane.position.y = -1.75
         plane.receiveShadow = true
         scene.add(plane)
         // cube
         const geometry = new THREE.BoxGeometry(2, 2, 2)
         const material = new THREE.MeshStandardMaterial({
            color: 0x87ceeb
         })
         const materialFolder = gui.addFolder('Material')
         materialFolder.add(material, 'wireframe')
         materialFolder.open()
         const cube = new THREE.Mesh(geometry, material)
         cube.position.set(0, 0.5, 0)
         cube.castShadow = true
         cube.receiveShadow = true
         scene.add(cube)
         // responsiveness
         window.addEventListener('resize', () => {
            width = window.innerWidth
            height = window.innerHeight
            camera.aspect = width / height
            camera.updateProjectionMatrix()
            renderer.setSize(window.innerWidth, window.innerHeight)
            renderer.render(scene, camera)
         })
         // renderer
         const renderer = new THREE.WebGL1Renderer()
         renderer.setSize(window.innerWidth, window.innerHeight)
         renderer.shadowMap.enabled = true
         renderer.shadowMap.type = THREE.PCFSoftShadowMap
         renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2))
         // animation
         function animate() {
         requestAnimationFrame(animate)
         cube.rotation.x += 0.005
         cube.rotation.y += 0.01
         renderer.render(scene, camera)
         }
         // rendering the scene
         const container = document.querySelector('#container')
         container.append(renderer.domElement)
         renderer.render(scene, camera)
         animate()
      </script>
   </body>
</html>

Output

threejs_lights_and_shadows.htm

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