Three.js implements cool 3D cinema example sharing

You can imagine that we are in a room. The room is a cube. If you have a good taste in life, you may put wallpaper in the room. Three.js can easily create a cube and paste textures around it. , put the camera in the cube, and the camera can rotate 360 ​​degrees to simulate a real scene. This article will share with you how to implement a cool 3D cinema using three.js.

Convert to code:

    const path = 'assets/image/'
    const format = '.jpg'
    const urls = [
      `${path}px${format}`, `${path}nx${format}`,
      `${path}py${format}`, `${path}ny${format}`,
      `${path}pz${format}`, `${path}nz${format}`
    ]
    const materials = []
    urls.forEach(url => {
      const textureLoader = new TextureLoader()
      textureLoader.setCrossOrigin(this.crossOrigin)
      const texture = textureLoader.load(url)
      materials.push(new MeshBasicMaterial({
        map: texture,
        overdraw: true,
        side: BackSide
      }))
    })
    const cube = new Mesh(new CubeGeometry(9000, 9000, 9000), new MeshFaceMaterial(materials))
    this.scene.add(cube)

• CubeGeometry creates an oversized cube

• MeshFaceMaterial attaches texture to the cube, due to the perspective It is inside the cube, so side: BackSide

2. Particle effect

A 3D model is composed of points, lines, and surfaces, and each part of the model can be traversed Points, convert each point into a geometric model, attach texture to it, copy the position of each point, and use these geometric models to reconstruct a model with only points. This is the basic principle of particle effects.

this.points = new Group()
    const vertices = []
    let point
    const texture = new TextureLoader().load('assets/image/dot.png')
    geometry.vertices.forEach((o, i) => {
      // 记录每个点的位置
      vertices.push(o.clone())
      const _geometry = new Geometry()
     // 拿到当前点的位置
      const pos = vertices[i]
      _geometry.vertices.push(new Vector3())
      const color = new Color()
      color.r = Math.abs(Math.random() * 10)
      color.g = Math.abs(Math.random() * 10)
      color.b = Math.abs(Math.random() * 10)
      const material = new PointsMaterial({
        color,
        size: Math.random() * 4 + 2,
        map: texture,
        blending: AddEquation,
        depthTest: false,
        transparent: true
      })
      point = new Points(_geometry, material)
      point.position.copy(pos)
      this.points.add(point)
    })
    return this.points

• new Group creates a group, which can be said to be a collection of particles

• ##Set particles and positions through point.position.copy(pos) , the coordinates are the same as the position of the corresponding point in the model

3. Click event processing

The click event of three.js requires the use of a ray caster (Raycaster). To facilitate understanding, please look at a picture first:

##Raycaster emits a ray, and intersectObject monitors the object hit by the ray

this.raycaster = new Raycaster()

// 把你要监听点击事件的物体用数组储存起来
this.seats.push(seat)

onTouchStart(event) {
    event.preventDefault()
    event.clientX = event.touches[0].clientX;
    event.clientY = event.touches[0].clientY;
    this.onClick(event)
  }

  onClick(event) {
    const mouse = new Vector2()
    mouse.x = ( event.clientX / this.renderer.domElement.clientWidth ) * 2 - 1
    mouse.y = - ( event.clientY / this.renderer.domElement.clientHeight ) * 2 + 1;
    this.raycaster.setFromCamera(mouse, this.camera)
   // 检测命中的座位
    const intersects = this.raycaster.intersectObjects(this.seats)
    if (intersects.length > 0) {
        intersects[0].object.material = new MeshLambertMaterial({
            color: 0xff0000
        })
    }
  }

intersects.length > 0 means that the ray hits a certain geometry
Lazy only implements the click implementation on the mobile side. If you want to see how to implement it on PC, please see thee. js official website
4. Initial use of shaders

Shaders are divided into vertex shaders and fragment shaders, written in GLSL language, and are a kind of GPU The language of communication, here I only talk about how to use

const vertext = `
   void main()
    {
    gl_Position = projectionMatrix * modelViewMatrix * vec4(position,1.0);
    }
  `

const fragment = `
    uniform vec2 resolution;
    uniform float time;

    vec2 rand(vec2 pos)
    {
    return fract( 0.00005 * (pow(pos+2.0, pos.yx + 1.0) * 22222.0));
    }
    vec2 rand2(vec2 pos)
    {
    return rand(rand(pos));
    }

    float softnoise(vec2 pos, float scale)
    {
    vec2 smplpos = pos * scale;
    float c0 = rand2((floor(smplpos) + vec2(0.0, 0.0)) / scale).x;
    float c1 = rand2((floor(smplpos) + vec2(1.0, 0.0)) / scale).x;
    float c2 = rand2((floor(smplpos) + vec2(0.0, 1.0)) / scale).x;
    float c3 = rand2((floor(smplpos) + vec2(1.0, 1.0)) / scale).x;

    vec2 a = fract(smplpos);
    return mix(
    mix(c0, c1, smoothstep(0.0, 1.0, a.x)),
    mix(c2, c3, smoothstep(0.0, 1.0, a.x)),
    smoothstep(0.0, 1.0, a.y));
    }

    void main(void)
    {
    vec2 pos = gl_FragCoord.xy / resolution.y;
    pos.x += time * 0.1;
    float color = 0.0;
    float s = 1.0;
    for(int i = 0; i < 8; i++)
    {
    color += softnoise(pos+vec2(i)*0.02, s * 4.0) / s / 2.0;
    s *= 2.0;
    }
    gl_FragColor = vec4(color);
    }
  `
// 设置物体的质材为着色器质材
 let material = new ShaderMaterial({
        uniforms: uniforms,
        vertexShader: vertext,
        fragmentShader: fragment,
        transparent: true,
      })

5. Halo effect

Since it is a simulated cinema, I want to make a projector to simulate the light emitted by the projector.

 // 光晕效果必须设置alpha = true
 const renderer = this.renderer = new WebGLRenderer({alpha: true, antialias: true})

 let textureFlare = new TextureLoader().load('assets/image/lensflare0.png')
      let textureFlare3 = new TextureLoader().load('assets/image/lensflare3.png')
      let flareColor = new Color(0xffffff)
      let lensFlare = new LensFlare(textureFlare, 150, 0.0 , AdditiveBlending, flareColor)
      lensFlare.add(textureFlare3, 60, 0.6, AdditiveBlending);
      lensFlare.add(textureFlare3, 70, 0.7, AdditiveBlending);
      lensFlare.add(textureFlare3, 120, 0.9, AdditiveBlending);
      lensFlare.add(textureFlare3, 70, 1.0, AdditiveBlending);
      lensFlare.position.set(0, 150, -85)

The main light is still simulated by lensflare0.png
textureFlare3 sets the range of the halo
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