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JavaScript+html5 canvas实现图片破碎重组动画特效

2016-02-22 12:03 826 查看

也许你见过HTML5图片破碎动画特效，实现的原理也挺简单的。但是你应该没有见过视频也可以破碎重组，这个HTML5动画就是利用Canvas的相关特性，实现了点击鼠标让视频破碎重组的效果。在视频区域点击鼠标，即可让该区域的视频破碎，让后经过一段时间后，破碎的区域又可以重组还原，视觉效果非常棒。

HTML代码

<div style="display:none">
<video id="sourcevid" autoplay="true" loop="true">
<source src="BigBuckBunny_640x360.mp4" type="video/mp4"/>
<source src="BigBuckBunny_640x360.ogv" type="video/ogg"/>
</video>
<canvas id="sourcecopy" width="640" height="360"></canvas>
</div>
<div>
<center>
<div style="z-index:1;position:relative;text-align:center;font-size:16px;font-weight:bold;width:1000px;top:60px;">Click video to blow it up!</div>
<canvas id="output" width="1000" height="600" onmousedown="dropBomb(event, this)" style="border: 0 none">    </canvas>
</center>
</div>

JavaScript代码

var video;
var copy;
var copycanvas;
var draw;
var TILE_WIDTH = 32;
var TILE_HEIGHT = 24;
var TILE_CENTER_WIDTH = 16;
var TILE_CENTER_HEIGHT = 12;
var SOURCERECT = {x:0, y:0, width:0, height:0};
var PAINTRECT = {x:0, y:0, width:1000, height:600};
function init(){
video = document.getElementById('sourcevid');
copycanvas = document.getElementById('sourcecopy');
copy = copycanvas.getContext('2d');
var outputcanvas = document.getElementById('output');
draw = outputcanvas.getContext('2d');
setInterval("processFrame()", 33);
}
function createTiles(){
var offsetX = TILE_CENTER_WIDTH+(PAINTRECT.width-SOURCERECT.width)/2;
var offsetY = TILE_CENTER_HEIGHT+(PAINTRECT.height-SOURCERECT.height)/2;
var y=0;
while(y < SOURCERECT.height){
var x=0;
while(x < SOURCERECT.width){
var tile = new Tile();
tile.videoX = x;
tile.videoY = y;
tile.originX = offsetX+x;
tile.originY = offsetY+y;
tile.currentX = tile.originX;
tile.currentY = tile.originY;
tiles.push(tile);
x+=TILE_WIDTH;
}
y+=TILE_HEIGHT;
}
}
var RAD = Math.PI/180;
var randomJump = false;
var tiles = [];
var debug = false;
function processFrame(){
if(!isNaN(video.duration)){
if(SOURCERECT.width == 0){
SOURCERECT = {x:0,y:0,width:video.videoWidth,height:video.videoHeight};
createTiles();
}
//this is to keep my sanity while developing
if(randomJump){
randomJump = false;
video.currentTime = Math.random()*video.duration;
}
//loop
if(video.currentTime == video.duration){
video.currentTime = 0;
}
}
var debugStr = "";
//copy tiles
copy.drawImage(video, 0, 0);
draw.clearRect(PAINTRECT.x, PAINTRECT.y,PAINTRECT.width,PAINTRECT.height);
for(var i=0; i<tiles.length; i++){
var tile = tiles[i];
if(tile.force > 0.0001){
//expand
tile.moveX *= tile.force;
tile.moveY *= tile.force;
tile.moveRotation *= tile.force;
tile.currentX += tile.moveX;
tile.currentY += tile.moveY;
tile.rotation += tile.moveRotation;
tile.rotation %= 360;
tile.force *= 0.9;
if(tile.currentX <= 0 || tile.currentX >= PAINTRECT.width){
tile.moveX *= -1;
}
if(tile.currentY <= 0 || tile.currentY >= PAINTRECT.height){
tile.moveY *= -1;
}
}else if(tile.rotation != 0 || tile.currentX != tile.originX || tile.currentY != tile.originY){
//contract
var diffx = (tile.originX-tile.currentX)*0.2;
var diffy = (tile.originY-tile.currentY)*0.2;
var diffRot = (0-tile.rotation)*0.2;
if(Math.abs(diffx) < 0.5){
tile.currentX = tile.originX;
}else{
tile.currentX += diffx;
}
if(Math.abs(diffy) < 0.5){
tile.currentY = tile.originY;
}else{
tile.currentY += diffy;
}
if(Math.abs(diffRot) < 0.5){
tile.rotation = 0;
}else{
tile.rotation += diffRot;
}
}else{
tile.force = 0;
}
draw.save();
draw.translate(tile.currentX, tile.currentY);
draw.rotate(tile.rotation*RAD);
draw.drawImage(copycanvas, tile.videoX, tile.videoY, TILE_WIDTH, TILE_HEIGHT, -TILE_CENTER_WIDTH, -TILE_CENTER_HEIGHT, TILE_WIDTH, TILE_HEIGHT);
draw.restore();
}
if(debug){
debug = false;
document.getElementById('trace').innerHTML = debugStr;
}
}
function explode(x, y){
for(var i=0; i<tiles.length; i++){
var tile = tiles[i];
var xdiff = tile.currentX-x;
var ydiff = tile.currentY-y;
var dist = Math.sqrt(xdiff*xdiff + ydiff*ydiff);
var randRange = 220+(Math.random()*30);
var range = randRange-dist;
var force = 3*(range/randRange);
if(force > tile.force){
tile.force = force;
var radians = Math.atan2(ydiff, xdiff);
tile.moveX = Math.cos(radians);
tile.moveY = Math.sin(radians);
tile.moveRotation = 0.5-Math.random();
}
}
tiles.sort(zindexSort);
processFrame();
}
function zindexSort(a, b){
return (a.force-b.force);
}
function dropBomb(evt, obj){
var posx = 0;
var posy = 0;
var e = evt || window.event;
if (e.pageX || e.pageY){
posx = e.pageX;
posy = e.pageY;
}else if (e.clientX || e.clientY) {
posx = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
posy = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
}
var canvasX = posx-obj.offsetLeft;
var canvasY = posy-obj.offsetTop;
explode(canvasX, canvasY);
}
function Tile(){
this.originX = 0;
this.originY = 0;
this.currentX = 0;
this.currentY = 0;
this.rotation = 0;
this.force = 0;
this.z = 0;
this.moveX= 0;
this.moveY= 0;
this.moveRotation = 0;
this.videoX = 0;
this.videoY = 0;
}
/*
getPixel
return pixel object {r,g,b,a}
*/
function getPixel(imageData, x, y){
var data = imageData.data;
var pos = (x + y * imageData.width) * 4;
return {r:data[pos], g:data[pos+1], b:data[pos+2], a:data[pos+3]}
}
/*
setPixel
set pixel object {r,g,b,a}
*/
function setPixel(imageData, x, y, pixel){
var data = imageData.data;
var pos = (x + y * imageData.width) * 4;
data[pos] = pixel.r;
data[pos+1] = pixel.g;
data[pos+2] = pixel.b;
data[pos+3] = pixel.a;
}
/*
copyPixel
faster then using getPixel/setPixel combo
*/
function copyPixel(sImageData, sx, sy, dImageData, dx, dy){
var spos = (sx + sy * sImageData.width) * 4;
var dpos = (dx + dy * dImageData.width) * 4;
dImageData.data[dpos] = sImageData.data[spos];   //R
dImageData.data[dpos+1] = sImageData.data[spos+1]; //G
dImageData.data[dpos+2] = sImageData.data[spos+2]; //B
dImageData.data[dpos+3] = sImageData.data[spos+3]; //A
}
</script>

希望本文所述对大家学习javascript程序设计有所帮助。

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