兼职做网站编辑/日本今日新闻头条

前言

shaders实现星系

    课程回顾

        使用顶点着色器为每个粒子设置动画

        a属性 ， u制服 ，v变化

        像素比：window.devicePixelRatio

        自动从渲染器检索像素比

            renderer.getPixelRatio()

        如何尺寸衰减， 放大缩小视角时，粒子都是同样大小的问题

        gl_Position += (1.0 / - viewPosition);

  

下面是实现的数学解释

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一、代码

这个我听的迷迷糊糊的，直接看代码中的注释吧

1.script.js

import * as THREE from 'three'
import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls.js'
import * as dat from 'lil-gui'
import galaxyVertexShader from './shaders/galaxy/vertex.glsl'
import galaxyFragmentShader from './shaders/galaxy/fragment.glsl'/*** Base*/
// Debug
const gui = new dat.GUI()// Canvas
const canvas = document.querySelector('canvas.webgl')// Scene
const scene = new THREE.Scene()/*** Galaxy*/
const parameters = {}
parameters.count = 200000
parameters.size = 0.005
parameters.radius = 6
parameters.branches = 3
parameters.spin = 1
parameters.randomness = 0.2
parameters.randomnessPower = 3
parameters.insideColor = '#ff6030'
parameters.outsideColor = '#1b3984'let geometry = null
let material = null
let points = nullconst generateGalaxy = () =>
{if(points !== null) // 制空{geometry.dispose()material.dispose()scene.remove(points)}/*** Geometry*/geometry = new THREE.BufferGeometry()// 这里为什么*3 因为要向各个方向发展，为什么*1只是在一个方向上拉伸const positions = new Float32Array(parameters.count * 3)const randomness = new Float32Array(parameters.count * 3)const colors = new Float32Array(parameters.count * 3)const scales = new Float32Array(parameters.count * 1)const insideColor = new THREE.Color(parameters.insideColor)const outsideColor = new THREE.Color(parameters.outsideColor)for(let i = 0; i < parameters.count; i++){const i3 = i * 3// Positionconst radius = Math.random() * parameters.radiusconst branchAngle = (i % parameters.branches) / parameters.branches * Math.PI * 2/*长时间就会发现星系在变薄，像一条丝带 ，应该避免下面代码 创建一个新的Float32Array并且在旋转后使用该属性 不应该在旋转之前添加应用随机性randomZXY*/const randomZ = Math.pow(Math.random(), parameters.randomnessPower) * (Math.random() < 0.5 ? 1 : - 1)  * parameters.randomness * radiusconst randomX = Math.pow(Math.random(), parameters.randomnessPower) * (Math.random() < 0.5 ? 1 : - 1)  * parameters.randomness * radiusconst randomY = Math.pow(Math.random(), parameters.randomnessPower) * (Math.random() < 0.5 ? 1 : - 1)  * parameters.randomness * radius// 旋转 将数据填充到位置上positions[i3    ] = Math.cos(branchAngle) * radiuspositions[i3 + 1] = 0.0positions[i3 + 2] = Math.sin(branchAngle) * radiusrandomness[i3    ] = randomXrandomness[i3 + 1] = randomYrandomness[i3 + 2] = randomZ// Colorconst mixedColor = insideColor.clone()mixedColor.lerp(outsideColor, radius / parameters.radius)colors[i3    ] = mixedColor.rcolors[i3 + 1] = mixedColor.gcolors[i3 + 2] = mixedColor.b// Scalescales[i] = Math.random()}geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3))geometry.setAttribute('aRandomness', new THREE.BufferAttribute(randomness, 3))geometry.setAttribute('color', new THREE.BufferAttribute(colors, 3))geometry.setAttribute('aScale', new THREE.BufferAttribute(scales, 1))/*** Material*/material = new THREE.ShaderMaterial({depthWrite: false,blending: THREE.AdditiveBlending,vertexColors: true,uniforms:{uTime: { value: 0 },uSize: { value: 30 * renderer.getPixelRatio() }  // 星系顶点尺寸*像素比},    vertexShader: galaxyVertexShader,fragmentShader: galaxyFragmentShader})/*** Points*/points = new THREE.Points(geometry, material)scene.add(points)
}gui.add(parameters, 'count').min(100).max(1000000).step(100).onFinishChange(generateGalaxy).name('数量')
gui.add(parameters, 'radius').min(0.01).max(20).step(0.01).onFinishChange(generateGalaxy).name('半径')
gui.add(parameters, 'branches').min(2).max(20).step(1).onFinishChange(generateGalaxy).name('条数')
gui.add(parameters, 'randomness').min(0).max(2).step(0.001).onFinishChange(generateGalaxy).name('随机')
gui.add(parameters, 'randomnessPower').min(1).max(10).step(0.001).onFinishChange(generateGalaxy).name('随机功率')
gui.addColor(parameters, 'insideColor').onFinishChange(generateGalaxy).name('内部颜色')
gui.addColor(parameters, 'outsideColor').onFinishChange(generateGalaxy).name('外部颜色')/*** Sizes*/
const sizes = {width: window.innerWidth,height: window.innerHeight
}window.addEventListener('resize', () =>
{// Update sizessizes.width = window.innerWidthsizes.height = window.innerHeight// Update cameracamera.aspect = sizes.width / sizes.heightcamera.updateProjectionMatrix()// Update rendererrenderer.setSize(sizes.width, sizes.height)renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2))
})/*** Camera*/
// Base camera
const camera = new THREE.PerspectiveCamera(75, sizes.width / sizes.height, 0.1, 100)
camera.position.x = 3
camera.position.y = 3
camera.position.z = 3
scene.add(camera)// Controls
const controls = new OrbitControls(camera, canvas)
controls.enableDamping = true/*** Renderer*/
const renderer = new THREE.WebGLRenderer({canvas: canvas
})
renderer.setSize(sizes.width, sizes.height)
renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2))/*** Generate the first galaxy*/
generateGalaxy()/*** Animate*/
const clock = new THREE.Clock()const tick = () =>
{const elapsedTime = clock.getElapsedTime()// Update materialmaterial.uniforms.uTime.value = elapsedTime// Update controlscontrols.update()// Renderrenderer.render(scene, camera)// Call tick again on the next framewindow.requestAnimationFrame(tick)
}tick()

2. 顶点着色器

uniform float uTime;
uniform float uSize;attribute vec3 aRandomness;
attribute float aScale;varying vec3 vColor;/* atan(x) 弧度 反正切函数
*/void main()
{/*** Position*/vec4 modelPosition = modelMatrix * vec4(position, 1.0);// Rotatefloat angle = atan(modelPosition.x, modelPosition.z); // 获取角度 偏移的float distanceToCenter = length(modelPosition.xz); // 到中心的距离float angleOffset = (1.0 / distanceToCenter) * uTime ; // 根据时间应该旋转多少度angle += angleOffset; // 更新角度 并且 角度加上角度偏移modelPosition.x = cos(angle) * distanceToCenter; // 更新到模型上，同时乘以到中心的距离modelPosition.z = sin(angle) * distanceToCenter;// Randomness 随机modelPosition.xyz += aRandomness;vec4 viewPosition = viewMatrix * modelPosition;vec4 projectedPosition = projectionMatrix * viewPosition;gl_Position = projectedPosition;/*** Size*/gl_PointSize = uSize * aScale;gl_PointSize *= (1.0 / - viewPosition.z);/*** Color*/vColor = color;
}

3.片段着色器

varying vec3 vColor;void main()
{// // Disc// float strength = distance(gl_PointCoord, vec2(0.5));// strength = step(0.5, strength);// strength = 1.0 - strength;// // Diffuse point// float strength = distance(gl_PointCoord, vec2(0.5));// strength *= 2.0;// strength = 1.0 - strength;// Light pointfloat strength = distance(gl_PointCoord, vec2(0.5));strength = 1.0 - strength;strength = pow(strength, 10.0);// Final colorvec3 color = mix(vec3(0.0), vColor, strength);gl_FragColor = vec4(color, 1.0);
}

二、效果

shaders - 星系

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总结

今天学的迷迷糊糊的，整体代码知道看得懂，思路，如何偏移以及一些数学计算很蒙！