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Anisotropic Filtering

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Anisotropic Filtering

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Description

Anisotropic Filtering allows us to improve the quality of the MIP maps.

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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 scene1 = new THREE.Scene()
const scene2 = new THREE.Scene()

const axesHelper1 = new THREE.AxesHelper(5)
scene1.add(axesHelper1)
const axesHelper2 = new THREE.AxesHelper(5)
scene2.add(axesHelper2)

const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000)
camera.position.set(0, -0.35, 0.2)

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

new OrbitControls(camera, renderer.domElement)

const planeGeometry1 = new THREE.PlaneGeometry(2, 25)
const planeGeometry2 = new THREE.PlaneGeometry(2, 25)

// const texture1 = new THREE.TextureLoader().load("img/grid.png")
// const texture2 = new THREE.TextureLoader().load("img/grid.png")

const mipmap = (size: number, color: string): HTMLCanvasElement => {
  const imageCanvas = document.createElement('canvas') as HTMLCanvasElement
  const context = imageCanvas.getContext('2d') as CanvasRenderingContext2D
  imageCanvas.width = size
  imageCanvas.height = size
  context.fillStyle = '#888888'
  context.fillRect(0, 0, size, size)
  context.fillStyle = color
  context.fillRect(0, 0, size / 2, size / 2)
  context.fillRect(size / 2, size / 2, size / 2, size / 2)
  return imageCanvas
}

const blankCanvas = document.createElement('canvas') as HTMLCanvasElement
blankCanvas.width = 128
blankCanvas.height = 128

const texture1 = new THREE.CanvasTexture(blankCanvas)
texture1.mipmaps[0] = mipmap(128, '#ff0000')
texture1.mipmaps[1] = mipmap(64, '#00ff00')
texture1.mipmaps[2] = mipmap(32, '#0000ff')
texture1.mipmaps[3] = mipmap(16, '#880000')
texture1.mipmaps[4] = mipmap(8, '#008800')
texture1.mipmaps[5] = mipmap(4, '#000088')
texture1.mipmaps[6] = mipmap(2, '#008888')
texture1.mipmaps[7] = mipmap(1, '#880088')
texture1.repeat.set(5, 50)
texture1.wrapS = THREE.RepeatWrapping
texture1.wrapT = THREE.RepeatWrapping

const texture2 = texture1.clone()
texture2.minFilter = THREE.NearestFilter
texture2.magFilter = THREE.NearestFilter

const material1 = new THREE.MeshBasicMaterial({ map: texture1 })
const material2 = new THREE.MeshBasicMaterial({ map: texture2 })

const plane1 = new THREE.Mesh(planeGeometry1, material1)
const plane2 = new THREE.Mesh(planeGeometry2, material2)

scene1.add(plane1)
scene2.add(plane2)

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

const options = {
  minFilters: {
    NearestFilter: THREE.NearestFilter,
    NearestMipMapLinearFilter: THREE.NearestMipMapLinearFilter,
    NearestMipMapNearestFilter: THREE.NearestMipMapNearestFilter,
    'LinearFilter ': THREE.LinearFilter,
    'LinearMipMapLinearFilter (Default)': THREE.LinearMipMapLinearFilter,
    LinearMipmapNearestFilter: THREE.LinearMipmapNearestFilter,
  },
  magFilters: {
    NearestFilter: THREE.NearestFilter,
    'LinearFilter (Default)': THREE.LinearFilter,
  },
}
const gui = new GUI()
const textureFolder = gui.addFolder('THREE.Texture')
textureFolder.add(texture2, 'minFilter', options.minFilters).onChange(() => updateMinFilter())
textureFolder.add(texture2, 'magFilter', options.magFilters).onChange(() => updateMagFilter())
textureFolder.add(texture2, 'anisotropy', 1, renderer.capabilities.getMaxAnisotropy()).onChange(() => updateAnistropy())
textureFolder.open()

function updateAnistropy() {
  material2.map = texture2.clone()
}
function updateMinFilter() {
  texture2.minFilter = Number(texture2.minFilter) as THREE.MinificationTextureFilter
  texture2.needsUpdate = true
}
function updateMagFilter() {
  texture2.magFilter = Number(texture2.magFilter) as THREE.MagnificationTextureFilter
  texture2.needsUpdate = true
}

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

function animate() {
  requestAnimationFrame(animate)

  render()

  stats.update()
}

function render() {
  renderer.setScissorTest(true)

  renderer.setScissor(0, 0, window.innerWidth / 2 - 2, window.innerHeight)
  renderer.render(scene1, camera)

  renderer.setScissor(window.innerWidth / 2, 0, window.innerWidth / 2 - 2, window.innerHeight)
  renderer.render(scene2, camera)

  renderer.setScissorTest(false)
}
animate()

Anisotropic Filtering : Wikipedia