(HSV HSB) to RGB

[SWF(width=720,height=360,backgroundColor=0x000000,frameRate=30)]

// ported from here:
//http://www.cs.rit.edu/~ncs/color/t_convert.html

function hsv(h:Number, s:Number, v:Number):Array{
	var r:Number, g:Number, b:Number;
	var i:int;
	var f:Number, p:Number, q:Number, t:Number;
	 
	if (s == 0){
		r = g = b = v;
		return [Math.round(r * 255), Math.round(g * 255), Math.round(b * 255)];
	}
	
	h /= 60;
	i  = Math.floor(h);
	f = h - i;
	p = v *  (1 - s);
	q = v * (1 - s * f);
	t = v * (1 - s * (1 - f));
	
	switch( i ) {
		case 0:
			r = v;
			g = t;
			b = p;
			break;
		case 1:
			r = q;
			g = v;
			b = p;
			break;
		case 2:
			r = p;
			g = v;
			b = t;
			break;
		case 3:
			r = p;
			g = q;
			b = v;
			break;
		case 4:
			r = t;
			g = p;
			b = v;
			break;
		default:		// case 5:
			r = v;
			g = p;
			b = q;
			break;
	}
	return [Math.round(r * 255), Math.round(g * 255), Math.round(b * 255)];
}


//
//  -- test it out by drawing a few things
//

var canvas:BitmapData = new BitmapData(720, 360, false, 0x000000);

addChild(new Bitmap(canvas));
 
canvas.lock();
var size:int = canvas.width * canvas.height;
var xp:int, yp:int, c:Array, i:int;

for (i = 0; i<size; i++){
	xp = i % 360;
	yp = i / 360;
	c =  hsv(xp, 1, yp / 360);
	canvas.setPixel(xp, yp, c[0] << 16 | c[1] << 8 | c[2]);
}

var dx:Number, dy:Number, dist:Number, ang:Number;

for (i = 0; i<size; i++){
	xp = i % 360;
	yp = i / 360;
	dx = xp - 180;
	dy = yp - 180;
	dist = 1 - Math.sqrt((dx * dx) + (dy * dy)) / 360;
	ang = Math.atan2(dy, dx) / Math.PI * 180;
	if (ang < 0){
		ang += 360;
	}
	c =  hsv(ang, 1, dist);
	canvas.setPixel(360 + xp, yp, c[0] << 16 | c[1] << 8 | c[2]);
}
canvas.unlock();

This is one of those things I’ve been meaning to play with for awhile. The above demos a function called hsv() which takes 3 arguments: angle (0-360), saturation(0-1) and value(0-1). The function returns an array of rgb values each with a range of (0-255).

There’s some room for optimization here, but for clarity I left as is. Even just playing with HSV (also know as HSB) for a few minutes, I see some interesting potential for dynamically generating color palettes for generative style experiments.

I looked around for the most elegant looking code snippet to port in order to write this… I eventually stumbled upon this great resource.

If you test the above on your timeline it will generate this image:

I usually only post one snippet a day… not sure why I decided to post two today.