displacement
Inside_Out_Displace(float 	Km = 0.1,
							blend = 0;
					string	OutSideTxt = "",
							InSideTxt = "")
{
float	hump1 = 0, hump2 = 0, F_Hump = 0, switch = 1;

/* STEP 1 - make a copy of the surface normal one unit in length */
normal n = normalize(N);
normal	nf = faceforward(n, I);

/* STEP 2 - calculate an appropriate value for the displacement */


if (OutSideTxt != "" || InSideTxt != "") 



if (switch == 1 && n == nf)	
	{
	hump1 = texture(OutSideTxt);
	hump2 = texture(InSideTxt);
	}
else if (switch == 1 && n != nf)
	{ 
	hump1 = texture(InSideTxt);
	hump2 = texture(OutSideTxt);
	}


F_Hump = mix(hump1, hump2, blend);

/* STEP 3 - calculate the new position of the surface point */
/*			"P" based on the value of hump */
P = P - n * F_Hump * Km;

/* STEP 4 - calculate the new orientation of the surface normal */
N = calculatenormal(P);
}