用p5.js制作烟花特效的示例代码

前⾔

之前看过⼀篇⽂章，使⽤processing制作烟花特效。效果如下

fireworks ⽹上调查了⼀圈了，发现processing是⼀个互动编程软件，java语⾔发展⽽来。⽽且动画效果是跑在processing专门的模拟器上。 不过好在也有对应的web扩展语⾔，有processing.js和p5.js。 processing.js在github上已经好⼏年没有⼈维护了，⼀些processing的特性⽀持不了。为此踩了不少坑， 本⽂就集中讲解如何⽤p5.js写烟花特效。代码讲解processing风格

function setup() { //processing初始化设置

createCanvas(window.innerWidth, window.innerHeight); frameRate(50);

imageMode(CENTER);}

function draw() { //循环执⾏，达成画⾯渲染效果 background(0, 0, 40);

for (var i = 0; i < fireworks.length; i++) { fireworks[i].display(); fireworks[i].update();

if (fireworks[i].needRemove()) { fireworks.splice(i, 1); } }}

烟花效果

function Fireworks(radius) {

var num = 512; //⼀发烟花⾥，有多少个点 (⽐较吃机器)

var centerPosition = new p5.Vector(random(width / 8, width * 7 / 8), random(height / 2, height * 4 / 5), random(-100, 100)); //烟花的中⼼位置 var velocity = new p5.Vector(0, -22, 0); var accel = new p5.Vector(0, 0.4, 0); var img;

var firePosition = []; var cosTheta; var sinTheta; var phi;

var colorChange = random(0, 5);

for (var i = 0; i < num; i++) {

cosTheta = random(0, 1) * 2 - 1;

sinTheta = sqrt(1 - cosTheta * cosTheta); phi = random(0, 1) * 2 * PI;

firePosition[i] = new p5.Vector(radius * sinTheta * cos(phi), radius * sinTheta * sin(phi), radius * cosTheta); //1发烟花⾥各个点的位置计算 firePosition[i] = p5.Vector.mult(firePosition[i], 1.12); }

//调整烟花随机颜⾊，使其更亮丽 if(colorChange>=3.8){

img=createLight(0.9,random(0.2,0.5),random(0.2,0.5)); }else if(colorChange>3.2){

img=createLight(random(0.2,0.5),0.9,random(0.2,0.5)); }else if(colorChange>2){

img=createLight(random(0.2,0.5),random(0.2,0.5),0.9); } else {

img=createLight(random(0.5,0.8),random(0.5,0.8),random(0.5,0.8)); }

this.display = function () { for (var i = 0; i < num; i++) { push();

translate(centerPosition.x, centerPosition.y, centerPosition.z); translate(firePosition[i].x, firePosition[i].y, firePosition[i].z); blendMode(ADD); //各个⼩点（发光源遮罩效果）

image(img, 0, 0); pop();

firePosition[i] = p5.Vector.mult(firePosition[i], 1.015); //更新⼩点（发光源）扩散位置 } }

this.update = function () { //模拟重⼒加速度

radius = dist(0, 0, 0, firePosition[0].x, firePosition[0].y, firePosition[0].z); centerPosition.add(velocity); velocity.add(accel); }

this.needRemove = function () {

if (centerPosition.y - radius > height) { return true; } else {

return false; } }}

随机发光源图⽚⽣成

function createLight(rPower, gPower, bPower) { var side = 64;

var center = side / 2.0;

var img = createImage(side, side); img.loadPixels();

for (var y = 0; y < side; y++) { for (var x = 0; x < side; x++) {

var distance = (sq(center - x) + sq(center - y)) / 10.0; var r = int((255 * rPower) / distance); var g = int((255 * gPower) / distance); var b = int((255 * bPower) / distance); // img.pixels[x + y * side] = color(r, g, b); img.set(y, x, color(r, g, b)); } }

img.updatePixels(); return img;}

接收键盘和屏幕触碰事件

function keyPressed() { //每事件添加⼀发烟花

fireworks.push(new Fireworks(80)); //80为烟花初始半径}

function touchStarted() { //每事件添加⼀发烟花 fireworks.push(new Fireworks(80)); return false;}

Github

以上就是本⽂的全部内容，希望对⼤家的学习有所帮助，也希望⼤家多多⽀持。