Shaders

radial shader

 
/* 
 * radial shader... dsward@webnation.com
 * this shader works best on a square panel.
 * it draws rays from the center to the edges.
*/
 
surface
radial(
	float majorAngle = 15;
	float minorAngle = 15;
	float spiralAngle = 45;
	float offsetAngle = 0;
	color specularColor = color(0, 0, 0); ) 
{
	float stDist;
	float curAngle;
	float taperAngle;
	float taperBase;
	float halfAngle;
	float midPt = 0.5;
	float ratio;
 
	/* measure the distance from midpoint s,t to current s,t */
	point pointA = (s, t, 0);
	point pointB = (midPt, midPt, 0);
	stDist = distance(pointA, pointB);
 
	/* measure the angle from midpoint s,t to current s,t */
	curAngle = degrees(atan((s - midPt), (t - midPt))) +
				offsetAngle + ((stDist * 2) * spiralAngle);
	if (curAngle < 0) curAngle = 360 + curAngle;
 
	/* find current angle within major angle */
	while (curAngle > majorAngle) curAngle = curAngle - majorAngle;
	
	if (curAngle < minorAngle)
	{
		taperAngle = minorAngle;
		halfAngle = taperAngle / 2;
		taperBase =  halfAngle - (minorAngle / 2);
		if (curAngle > taperBase)
		{
			if (curAngle < (minorAngle - taperBase))
			{
				if (curAngle > (minorAngle / 2))
				{
					curAngle = minorAngle - curAngle;
				}
				Ci = mix (Cs, specularColor, smoothstep (0, halfAngle, curAngle));
			}
			else
			{
				Ci = Cs;
			}
		}
		else
		{
			Ci = Cs;
		}
	}
	else
	{
		Ci = Cs;
	}	
}