/* 
wgsComposite AOV shader
Jan 20 2010
This shader adds two outputs to a standard ambeint/diffuse/specular lightshader:
1. _depth - calculates a depth if shader is applied, meaning,
			if the shader is not applied, depth is occluded
2. _zmask - alpha channel for masking out objects that do not want depth.
			this is available but not always needed.
One can easily take these two component and add them to any shader.
*/
surface
wgsComposite(color	Ka = color(0.15,0.15,0.15),	/* ambient brightness */
					Kd = color(0.80,0.80,0.80),	/* basic brightness */
					Ks = color(0.70,0.70,0.70);	/* hilite brightness */
			float	roughness = 0.1;			/* hilite spread */
			color 	hilitecolor = 1;			/* hilite color */ 
			string	texturefile = "";
			output varying float _depth = 0;
			output varying float _zmask = 1;)
{
color	ambientcolor, diffusecolor, speccolor,surfcolor = 1;
		
if (texturefile != "")
	surfcolor = surfcolor * color texture(texturefile, s, 1-t);
else
	surfcolor = 1;

normal	n = normalize(N);
normal	nf = faceforward(n, I);
vector	i = normalize(-I);

Oi = Os;

ambientcolor = Ka * ambient();
diffusecolor = Kd * diffuse(nf);
speccolor = Ks * specular(nf, i, roughness) * hilitecolor;
_depth = depth(P);
_zmask = 1;

Ci = Oi * Cs * surfcolor * (ambientcolor + diffusecolor + speccolor);
}