Canvas 梦幻树生长动画-编程知识

Canvas 梦幻树生长动画

canvas可以制作出非常炫酷的动画，以下是一个梦幻树的示例。

效果图

在这里插入图片描述

源代码

							<!DOCTYPE>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>梦幻数生长动画</title><script type="text/javascript" src=" http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
<script type="text/javascript">
(function ($) {var Vector = function (x, y) {this.x = x || 0;this.y = y || 0;};Vector.prototype = {add: function (v) {this.x += v.x;this.y += v.y;return this;},length: function () {return Math.sqrt(this.x * this.x + this.y * this.y);},rotate: function (theta) {var x = this.x;var y = this.y;this.x = Math.cos(theta) * this.x - Math.sin(theta) * this.y;this.y = Math.sin(theta) * this.x + Math.cos(theta) * this.y;//this.x = Math.cos(theta) * x - Math.sin(theta) * y;//this.y = Math.sin(theta) * x + Math.cos(theta) * y;return this;},mult: function (f) {this.x *= f;this.y *= f;return this;}};var Leaf = function (p, r, c, ctx) {this.p = p || null;this.r = r || 0;this.c = c || 'rgba(255,255,255,1.0)';this.ctx = ctx;}Leaf.prototype = {render: function () {var that = this;var ctx = this.ctx;var f = Branch.random(1, 2)for (var i = 0; i < 5; i++) {(function (r) {setTimeout(function () {ctx.beginPath();ctx.fillStyle = that.color;ctx.moveTo(that.p.x, that.p.y);ctx.arc(that.p.x, that.p.y, r, 0, Branch.circle, true);ctx.fill();}, r * 60);})(i);}}}var Branch = function (p, v, r, c, t) {this.p = p || null;this.v = v || null;this.r = r || 0;this.length = 0;this.generation = 1;this.tree = t || null;this.color = c || 'rgba(255,255,255,1.0)';this.register();};Branch.prototype = {register: function () {this.tree.addBranch(this);},draw: function () {var ctx = this.tree.ctx;ctx.beginPath();ctx.fillStyle = this.color;ctx.moveTo(this.p.x, this.p.y);ctx.arc(this.p.x, this.p.y, this.r, 0, Branch.circle, true);ctx.fill();},modify: function () {var angle = 0.18 - (0.10 / this.generation);this.p.add(this.v);this.length += this.v.length();this.r *= 0.99;this.v.rotate(Branch.random(-angle, angle)); //.mult(0.996);if (this.r < 0.8 || this.generation > 10) {this.tree.removeBranch(this);var l = new Leaf(this.p, 10, this.color, this.tree.ctx);l.render();}},grow: function () {this.draw();this.modify();this.fork();},fork: function () {var p = this.length - Branch.random(100, 200); // + (this.generation * 10);if (p > 0) {var n = Math.round(Branch.random(1, 3));this.tree.stat.fork += n - 1;for (var i = 0; i < n; i++) {Branch.clone(this);}this.tree.removeBranch(this);}}};Branch.circle = 2 * Math.PI;Branch.random = function (min, max) {return Math.random() * (max - min) + min;};Branch.clone = function (b) {var r = new Branch(new Vector(b.p.x, b.p.y), new Vector(b.v.x, b.v.y), b.r, b.color, b.tree);r.generation = b.generation + 1;return r;};Branch.rgba = function (r, g, b, a) {return 'rgba(' + r + ',' + g + ',' + b + ',' + a + ')';};Branch.randomrgba = function (min, max, a) {return Branch.rgba(Math.round(Branch.random(min, max)), Math.round(Branch.random(min, max)), Math.round(Branch.random(min, max)), a);};var Tree = function () {var branches = [];var timer;this.stat = {fork: 0,length: 0};this.addBranch = function (b) {branches.push(b);};this.removeBranch = function (b) {for (var i = 0; i < branches.length; i++) {if (branches[i] === b) {branches.splice(i, 1);return;}}};this.render = function (fn) {var that = this;timer = setInterval(function () {fn.apply(that, arguments);if (branches.length > 0) {for (var i = 0; i < branches.length; i++) {branches[i].grow();}}else {//clearInterval(timer);}}, 1000 / 30);};this.init = function (ctx) {this.ctx = ctx;};this.abort = function () {branches = [];this.stat = {fork: 0,length: 0}};};function init() {// initvar $window = $(window);var $body = $("body");var canvas_width = $window.width();var canvas_height = $window.height();var center_x = canvas_width / 2;var stretch_factor = 600 / canvas_height;var y_speed = 3 / stretch_factor;var $statMsg = $("#statMsg");// txvar canvas = $('#canvas')[0];canvas.width = canvas_width;canvas.height = canvas_height;var ctx = canvas.getContext("2d");ctx.globalCompositeOperation = "lighter";// treevar t = new Tree();t.init(ctx);for (var i = 0; i < 3; i++) {new Branch(new Vector(center_x, canvas_height), new Vector(Math.random(-1, 1), -y_speed), 15 / stretch_factor, Branch.randomrgba(0, 255, 0.3), t);}t.render(function () {$statMsg.html(this.stat.fork);});}$(function () {init();});})(jQuery);</script><style type="text/css">body {padding: 0;margin: 0;background: #fff;font-family: Courier;}
canvas {background-color: #000;cursor: pointer;}
</style></head>
<body><canvas id='canvas'></canvas></body>
</html>