基于HTML5 Canvas实现视频破碎重组特效

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，然后经过一段时间，破碎的区域又可以重组还原，视觉效果也很棒，非常值得一试。

在线演示      源码下载

		
		



	
Click video to blow it up!
	        

　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

}


 原文：http://www.codeceo.com/article/html5-broken-video.html