surface
diffuse_test(float Kd = 1;
	output varying float __shadow = 0;
	output varying float __inshadow = 0;
	output varying color __no_shadow_ci)
{
color surfcolor = 1; 

normal n = normalize(N);
vector nf = faceforward(n, I);
Oi = Os; 

color diffusecolor = 0;
float shad = 0;
color totalLightColor = 0;
illuminance(P, n, PI) {
	//Query the current light for the value
	//of it's output parameter
	if(lightsource("__inshadow",shad) == 1)
		__shadow += shad;
		
	// Same again for the light color that was 
	//not darkened by a shadow
	color cl = 0;
	if(lightsource("__cl_noshadow", cl) == 1)	
		totalLightColor += cl * normalize(L).n;
		
	//Are we in the "self shadowing" part
	//of the surface??
	float dot = n.normalize(-L);
	if(dot >= 0)
		__shadow = 1;

		
	diffusecolor += Cl * normalize(L).n;
	}
	
diffusecolor *= Kd; 
	
	Ci = Oi * Cs * surfcolor * diffusecolor;
	__no_shadow_ci = Oi * Cs * surfcolor * totalLightColor * Kd;  
}