众所周知，前不久刚热播的《打火机与公主裙》中出现了编程中的一幕：一颗跳动的爱心，所以作为一个整活up主，当然少不了要来横插一脚，所以今天就带大家复刻一下电视剧中的爱心桥段，那么为了拥有如此装逼的技术，up主都用了哪些手段呢？
手段1：c++语言的基础，我们先来看看最简单的C语言运行出来的字符型静态爱心是怎么来的，话不多说，直接上代码链接：
#include <stdio.h> int main() { float a,x,y; for(y = -1.5f; y < 1.5f; y += 0.1f) { for(x = 1.5f; x > -1.5f; x -= 0.05f) { a = x * x + y * y - 1; char ch = a * a *a - x * x *y * y * y <= 0.0f ? '*' : ' '; putchar(ch); } printf("\n"); } return 0; }
其实呢逻辑也没有那么复杂，就是在一个圆中抠出来一个爱心的形状就完了，就如电视剧中男主说的，高数不挂都能看懂。
那么第二种就开始有点挑战性了，一开始up主呢是想像电视剧一样通过C语言纯代码来实习，奈何实在是C语言功力不到位，于是转战到了自己擅长的网站开发领域，使用了html5的canvas来绘制出了一个爱心，网络上的代码呢终究是殊途同归，那么下面我们就来介绍一下canvas这门技术到底是什么？
HTML5 Canvas | 菜鸟教程
总的来说，canvas就是通过JavaScript在画布上面绘制一系列图片的工具，具体的方法可以参考菜鸟教程上的详细方法，下面为大家分享一下我的源码
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>整活大队</title> <link rel="shortcut icon" href="../../assets/images/icon/favicon.ico" type="image/x-icon"> <style> html, body { height: 100%; padding: 0; margin: 0; background-image: url("https://gimg2.baidu.com/image_search/src=http://picnew10.photophoto.cn/20160706/xuanlixingkongbeijing-23193270_1.jpg&refer=http://picnew10.photophoto.cn&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1670479907&t=0c2d3f69b945926f461d3f02912e17f3"); width: 100%; height: 100%; } canvas { position: absolute; width: 100%; height: 100%; } </style> </head> <body> <canvas id="pink"> Canvas Not Support </canvas> <script> /* * Settings */ let settings = { particles: { length: 500, duration: 2, velocity: 100, effect: -0.75, size: 30, }, }; (function () { let b = 0; let c = ["ms", "moz", "webkit", "o"]; for (let a = 0; a < c.length && !window.requestAnimationFrame; ++a) { window.requestAnimationFrame = window[c[a] + "RequestAnimationFrame"]; window.cancelAnimationFrame = window[c[a] + "CancelAnimationFrame"] || window[c[a] + "CancelRequestAnimationFrame"] } if (!window.requestAnimationFrame) { window.requestAnimationFrame = function (h, e) { let d = new Date().getTime(); let f = Math.max(0, 16 - (d - b)); let g = window.setTimeout(function () { h(d + f) }, f); b = d + f; return g } } if (!window.cancelAnimationFrame) { window.cancelAnimationFrame = function (d) { clearTimeout(d) } } }() ); /* * Point class */ let Point = (function () { function Point(x, y) { this.x = (typeof x !== 'undefined') ? x : 0; this.y = (typeof y !== 'undefined') ? y : 0; } Point.prototype.clone = function () { return new Point(this.x, this.y); }; Point.prototype.length = function (length) { if (typeof length == 'undefined') return Math.sqrt(this.x * this.x + this.y * this.y); this.normalize(); this.x *= length; this.y *= length; return this; }; Point.prototype.normalize = function () { let length = this.length(); this.x /= length; this.y /= length; return this; }; return Point; })(); let Particle = (function () { function Particle() { this.position = new Point(); this.velocity = new Point(); this.acceleration = new Point(); this.age = 0; } Particle.prototype.initialize = function (x, y, dx, dy) { this.position.x = x; this.position.y = y; this.velocity.x = dx; this.velocity.y = dy; this.acceleration.x = dx * settings.particles.effect; this.acceleration.y = dy * settings.particles.effect; this.age = 0; }; Particle.prototype.update = function (deltaTime) { this.position.x += this.velocity.x * deltaTime; this.position.y += this.velocity.y * deltaTime; this.velocity.x += this.acceleration.x * deltaTime; this.velocity.y += this.acceleration.y * deltaTime; this.age += deltaTime; }; Particle.prototype.draw = function (context, image) { function ease(t) { return (--t) * t * t + 1; } let size = image.width * ease(this.age / settings.particles.duration); context.globalAlpha = 1 - this.age / settings.particles.duration; context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size); }; return Particle; })(); let ParticlePool = (function () { let particles, firstActive = 0, firstFree = 0, duration = settings.particles.duration; function ParticlePool(length) { particles = new Array(length); for (let i = 0; i < particles.length; i++) particles[i] = new Particle(); } ParticlePool.prototype.add = function (x, y, dx, dy) { particles[firstFree].initialize(x, y, dx, dy); firstFree++; if (firstFree == particles.length) firstFree = 0; if (firstActive == firstFree) firstActive++; if (firstActive == particles.length) firstActive = 0; }; ParticlePool.prototype.update = function (deltaTime) { let i; if (firstActive < firstFree) { for (i = firstActive; i < firstFree; i++) particles[i].update(deltaTime); } if (firstFree < firstActive) { for (i = firstActive; i < particles.length; i++) particles[i].update(deltaTime); for (i = 0; i < firstFree; i++) particles[i].update(deltaTime); } while (particles[firstActive].age >= duration && firstActive != firstFree) { firstActive++; if (firstActive == particles.length) firstActive = 0; } }; ParticlePool.prototype.draw = function (context, image) { if (firstActive < firstFree) { for (i = firstActive; i < firstFree; i++) particles[i].draw(context, image); } if (firstFree < firstActive) { for (i = firstActive; i < particles.length; i++) particles[i].draw(context, image); for (i = 0; i < firstFree; i++) particles[i].draw(context, image); } }; return ParticlePool; })(); (function (canvas) { let context = canvas.getContext('2d'), particles = new ParticlePool(settings.particles.length), particleRate = settings.particles.length / settings.particles.duration, // particles/sec time; function pointOnHeart(t) { return new Point( 160 * Math.pow(Math.sin(t), 3), 130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25 ); } let image = (function () { let canvas = document.createElement('canvas'), context = canvas.getContext('2d'); canvas.width = settings.particles.size; canvas.height = settings.particles.size; function to(t) { let point = pointOnHeart(t); point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350; point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350; return point; } context.beginPath(); let t = -Math.PI; let point = to(t); context.moveTo(point.x, point.y); while (t < Math.PI) { t += 0.01; point = to(t); context.lineTo(point.x, point.y); } context.closePath(); context.fillStyle = '#ea80b0'; context.fill(); let image = new Image(); image.src = canvas.toDataURL(); return image; })(); function render() { requestAnimationFrame(render); let newTime = new Date().getTime() / 1000, deltaTime = newTime - (time || newTime); time = newTime; context.clearRect(0, 0, canvas.width, canvas.height); let amount = particleRate * deltaTime; for (let i = 0; i < amount; i++) { let pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random()); let dir = pos.clone().length(settings.particles.velocity); particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y); } particles.update(deltaTime); particles.draw(context, image); } function onResize() { canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight; } window.onresize = onResize; setTimeout(function () { onResize(); render(); }, 10); })(document.getElementById('pink')); </script> </body> </html>
