HTML5 Canvas の断片化と再構成のビデオ特殊効果コードの詳細な紹介

おそらく、HTML5 の画像を破壊するアニメーションの特殊効果を見たことがあるでしょう。実装の原理は非常に単純です。しかし、この HTML5 アニメーションは、Canvas の関連機能を使用して、マウスをクリックするだけでビデオを分割および再構成できることを見たことがないかもしれません。ビデオ領域でマウスをクリックすると、その領域でビデオが中断されます。一定時間が経過すると、中断された領域が再構成されて復元され、視覚効果は優れています。

オンラインデモのソースコードダウンロード

HTMLコード

<p 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>
</p>
<p>
<center>
	<p 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!</p>
	<canvas id="output" width="1000" height="600" onmousedown="dropBomb(event, this)" style="border: 0 none">        </canvas>
</center>
</p>

JavaScriptコード

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(&#39;trace&#39;).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>

上記は、HTML5 Canvasの壊れて再構成されたビデオ特殊効果コードの詳細な紹介であり、その他の関連コンテンツについては、注目してください。 PHP 中国語 Web サイト (www.php .cn)!