function resize(){
	var canvas2 = document.getElementById('myCanvas2');  
	canvas2.width = window.innerWidth; 
}
window.onresize = function(){
	resize();
}
resize();

;(function(){
	wave2();
})();
/* 第二条 */
function wave2(){
	var waveWidthB = 7680,
	offsetB = 0,
	waveHeightB = 100,  //波浪高度
	waveCountB = 6,  //波浪个数
	startXB = -3840,
	startYB = 200,   //canvas 高度
	progressB = 100,  //波浪位置的高度
	d2B = waveWidthB / waveCountB,
	dB = d2B / 2,
	hdB = dB / 2,
	cB = document.getElementById("myCanvas2"),
	ctxB = cB.getContext("2d");
	function tickB() {
		offsetB -= 5;
		if (-1 * offsetB === d2B) offsetB = 0;
		ctxB.clearRect(0, 0, cB.width, cB.height);
		ctxB.globalAlpha = 1;
		ctxB.fillStyle = '#fff';
		ctxB.beginPath();
		var offsetYB = startYB - progressB;  
		ctxB.moveTo(startXB - offsetB, offsetYB);
		for (var i = 0; i < waveCountB; i++) {
			var dxB = i * d2B;
			var offsetXB = dxB + startXB - offsetB;
			ctxB.quadraticCurveTo(offsetXB + hdB, offsetYB + waveHeightB, offsetXB + dB, offsetYB);

			ctxB.quadraticCurveTo(offsetXB + hdB + dB, offsetYB - waveHeightB, offsetXB + d2B, offsetYB);
		}
		ctxB.lineTo(startXB + waveWidthB, 3000);
		ctxB.lineTo(startXB, 3000);
		ctxB.fill();
		setTimeout(tickB,20); //速度
		//requestAnimationFrame(tick);
	}
	tickB();
}