p5.js简介

前一段时间偶然了解到一个觉得很好玩儿的东西p5.js,于是就去了解了一下，发现可以自己设计一些有趣的动画效果，设计出来的动画可以放置到页面当中，而且也是简单易学的。

下面是一段官方的介绍：

p5.js是一个以 Processing语言（java的图形化语言）为基础的JavaScript 库，经常用于互联网数据可视化和互动艺术创作。它继承了Processing语言的初衷，通过简单的编程即可表达数字创意

home | p5.js (p5js.org)，这个是p5.js的教程网站，配套的有远程的p5编辑器链接。但是，由于p5的编译器需要翻外网才能使用，因此，为了服务于大多数群众，本篇博客将使用vscode来实现p5.js的动画效果。

使用vscode来在本地跑p5.js的项目

前期准备

1.去vscode扩展里面搜索p5.js，下载下面这几个拓展应用并且下载

2.新建个文件夹，使用快捷键，shift+ctrl+p，快速创建一个 p5 project

3.给自己创建的p5 project 起个项目名字，（这里，我的名字是windMill，因为我们即将要做一个风车动画）

4.此时，我们可以看到默认创建的index.html和sketch.js两个文件

5.点击侧边栏的雪花按钮，可以看到自己在该文件夹下创建的p5 项目，点击运行按钮，可以在vscode自带的浏览器看到运行的情况

当然也可以直接将html使用浏览器打开查看效果，由于在sketch.js里面，有创建画布

function setup() {
  createCanvas(400, 400);
}
//在js代码中，setup()函数主要用于设置程序初始状态的代码（比如画布大小，刷新频率，色彩模式等等）
//draw()函数主要用户图形绘制的功能代码（色彩填充，绘制图像）

通过F12键进行检查，直接就可以看到有一个400*400的画布

核心代码

sketch.js


function triangleWave(x, t, a, p = 0) {
  const temp = (x + p) / t * 2
  const integer = Math.trunc(temp)
  const fraction = temp - integer
  if (integer % 2 === 0) {
    return a * (fraction - 0.5)
  } else {
    return a * (0.5 - fraction)
  }
}


const speed = 0.01
const period = 1.5
let t = 0

let windmillTower
let windmillFan

function preload() {
  windmillTower = loadImage('asset1/windmill_tower.svg')
  windmillFan = loadImage('asset1/windmill_fan.svg')
}

function setup() {
  createCanvas(500, 500, WEBGL)
}

function draw() {
  background(249, 145, 190)
  scale(1, 1 - triangleWave(t += speed, period, 0.3))
  shearX(PI / 12 * triangleWave(t += speed, 2 * period, 1))
  // rect(-50, -100, 100, 100)
  image(windmillTower, -50, -100, 100, 100)
  push()
  translate(0, -90)
  rotate(10 * t)
  image(windmillFan, -50, -50, 100, 100)
  pop()
}

风车风叶的svg格式代码

<svg xmlns="http://www.w3.org/2000/svg" width="701.1049" height="701.0992" viewBox="0 0 701.1049 701.0992">
  <title>windmill_fan</title>
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    <g id="Layer_1" data-name="Layer 1">
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      </g>
    </g>
  </g>
</svg>

风车塔身svg格式图片代码

<svg xmlns="http://www.w3.org/2000/svg" width="361.1963" height="622.5976" viewBox="0 0 361.1963 622.5976">
  <title>windmill_tower</title>
  <g id="å¾å±_2" data-name="å¾å± 2">
    <g id="Layer_1" data-name="Layer 1">
      <g>
        <g>
          <polygon points="180.601 127.207 136.212 127.207 104.463 622.598 180.601 622.598 250.674 622.598 218.919 127.207 180.601 127.207" fill="#e06d4e"/>
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        </g>
        <rect x="125.8413" y="478.7353" width="101.2446" height="143.8623" fill="#43778e"/>
        <polygon points="116.612 478.735 176.464 435.811 236.309 478.735 116.612 478.735" fill="#39657a"/>
        <g>
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        </g>
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</svg>