canvas绘制科赫雪花
<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>