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Custom Mipmaps

Video Lecture

Custom Mipmaps Custom MipMap

Description

You can create your own custom mipmaps to be used when texture pixels are drawn depending on distances from the camera and whether the texel needs to be minified or magnified.

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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.z = 1

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()
const planeGeometry2 = new THREE.PlaneGeometry()

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

const mipmap = (size: number, color: string) => {
    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, 5)
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.open()

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()

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