I wrote simple function to this magical symbol I like so much:
<!doctype html>
<html>
<body>
<canvas id="c" width="500" height="500"></canvas>
<script>
var ctx = (document.getElementById("c")).getContext("2d");
// draws rotated pentagram with or without cirle
function pentagram( ctx, x, y, radius, rotate, circle )
{
ctx.beginPath();
for ( var i = 0; i <= 4 * Math.PI; i += ( 4 * Math.PI ) / 5 ) {
ctx.lineTo( x + radius * Math.cos(i + rotate), y + radius * Math.sin(i + rotate));
}
if ( circle ) {
ctx.moveTo( x + radius, y );
ctx.arc(x, y, radius, 0, Math.PI * 2, false);
}
ctx.stroke();
}
pentagram ( ctx, 250, 250, 60, Math.PI/2, true);
</script>
</body>
</html>
Results (on Chromium 10 on GNU/Linux) with and without circles are here:
