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脚本之家。