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canvas绘制科赫雪花

canvas 
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<html>
	<head>
		<title>JS</title>
		
	</head>
	<body>
	<canvas id="square" width=500 height=500></canvas>
	<script>
		var deg = Math.PI/180;
		
	function snowflake(c, n, x, y, len) {    
		c.save();           // Save current transformation    
		c.translate(x,y);   // Translate origin to starting point    
		c.moveTo(0,0);      // Begin a new subpath at the new origin    
		leg(n);             // Draw the first leg of the snowflake    
		c.rotate(-120*deg); // Now rotate 120 degrees counterclockwise    
		leg(n);             // Draw the second leg    
		c.rotate(-120*deg); // Rotate again    
		leg(n);             // Draw the final leg    
		c.closePath();      // Close the subpath    
		c.restore();        // And restore original transformation    
		// Draw a single leg of a level-n Koch snowflake.    
		// This function leaves the current point at the end of the leg it has    
		// drawn and translates the coordinate system so the current point is (0,0).    
		// This means you can easily call rotate() after drawing a leg.    
		function leg(n) {        c.save();               // Save the current transformation        
			if (n == 0) {           // Nonrecursive case:            
				c.lineTo(len, 0);   //   Just draw a horizontal line        
			}                       //                                       _  _        
			else {                  // Recursive case: draw 4 sub-legs like:  \/            
				c.scale(1/3,1/3);   // Sub-legs are 1/3rd the size of this leg            
				leg(n-1);           // Recurse for the first sub-leg            
				c.rotate(60*deg);   // Turn 60 degrees clockwise            
				leg(n-1);           // Second sub-leg            
				c.rotate(-120*deg); // Rotate 120 degrees back            
				leg(n-1);           // Third sub-leg            
				c.rotate(60*deg);   // Rotate back to our original heading            
				leg(n-1);           // Final sub-leg        
				}        c.restore();            // Restore the transformation        
				c.translate(len, 0);    // But translate to make end of leg (0,0)    
				}}
		
		var canvas = document.getElementById("square");
		c2 = canvas.getContext("2d");
		
		snowflake(c2,4,150,115,125);
		c2.stroke();
	</script>
		
		<!--<svg>
			<defs>
				<linearGradient id="fade">
					<stop offset="0%" stop-color="#008"/>
					<stop offset="100%" stop-color="#ccf"/>
				</linearGradient>
			</defs>
			
			<rect x="100" y="100" width="300" height="200" stroke="black" stroke-width="25" fill="url(#fade)"/>
		
		</svg>-->
		
		<input type="button" value="input" onclick="aaa()"/>
	</body>
</html>
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