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
https://github.com/cangyan/TAV/tree/master/00003_P5_FIREWORKS
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。
