Just another update

Task/Mandelbrot-set/JavaScript/mandelbrot-set.js

@@ -0,0 +1,69 @@
+function Mandeliter( cx, cy, maxiter ){
+  var
+    x = 0.0,
+    y = 0.0,
+    xx = 0,
+    yy = 0,
+    xy = 0;
+
+  var i = maxiter;
+  while( i-- && xx + yy <= 4 ){
+    xy = x * y;
+    xx = x * x;
+    yy = y * y;
+    x = xx - yy + cx;
+    y = xy + xy + cy;
+  }
+  return maxiter - i;
+}
+
+function Mandelbrot( width,height, xmin,xmax, ymin,ymax, iterations ){
+  var canvas = document.createElement( 'canvas' );
+  canvas.width = width;
+  canvas.height = height;
+
+  var ctx = canvas.getContext( '2d' );
+  var img = ctx.getImageData( 0, 0, width, height );
+  var pix = img.data;
+  for( var ix = 0; ix < width; ++ix )
+    for( var iy = 0; iy < height; ++iy )
+    {
+      var x = xmin + (xmax - xmin) * ix / (width - 1);
+      var y = ymin + (ymax - ymin) * iy / (height - 1);
+      var i = Mandeliter( x, y, iterations );
+      var ppos = 4 * (width * iy + ix);
+      if( i === iterations )
+      {
+        pix[ppos] = 0;
+        pix[ppos+1] = 0;
+        pix[ppos+2] = 0;
+      }
+      else
+      {
+        var c = 3 * Math.log(i)/Math.log(iterations - 1.0);
+        if (c < 1)
+        {
+          pix[ppos] = 255*c;
+          pix[ppos+1] = 0;
+          pix[ppos+2] = 0;
+        }
+        else if( c < 2 )
+        {
+          pix[ppos] = 255;
+          pix[ppos+1] = 255*(c-1);
+          pix[ppos+2] = 0;
+        }
+        else
+        {
+          pix[ppos] = 255;
+          pix[ppos+1] = 255;
+          pix[ppos+2] = 255*(c-2);
+        }
+      }
+      pix[ ppos+3 ] = 255;
+    }
+  ctx.putImageData( img, 0,0 );
+  document.body.insertBefore( canvas, document.body.childNodes[0] );
+}
+
+Mandelbrot( 900,600, -2,1, -1,1, 1000 );