/*----------------------------------------------------------------------
*
* dswknurl.sl - dsward@webnation.com
* this shader wraps a sinusoidal displacement on the surface
* .
*
* freq - "frequency" of the knurl
* depth - magnitude of knurl
* sORt - direction of knurl, 0=s, 1=t
*--------------------------------------------------------------------*/
displacement
dswknurl(float freq = 100, depth = 0.005, sORt = 0)
{
varying point sN;
varying float position, amplitude;
P = transform("shader", P);
N = transform("shader", N + point "shader" (0,0,0));
if (sORt == 0)
{
position = s;
}
else
{
position = t;
}
amplitude = sin(2 * PI * freq * position) - 1;
P += normalize(N) * amplitude * depth;
P = transform("shader", "current", P);
N = calculatenormal(P);
}
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