surface
metal (
	float	Ka		= 1, 
		Ks		= 1, 
		roughness	= 0.3)
{
	normal n = faceforward(normalize(N), I);
	vector i = normalize(-I);
	Oi = Os;

	//ambient
	color am = Ka*ambient();
	am = Ka*diffuse(n);
	float a = comp(am,0.0)+comp(am,1.0)+comp(am,2.0);
	if (a < 2.0)
		Ci = Cs*0.7*am;
	else 
		Ci = Cs*1.1*am;

	// outline
	if(i.n < 0.3) {
		Ci = Ci*0;
		Oi = 1;
	}

}