newmtl grey
Ka  0.3 0.3 0.3 
Kd  0.5 0.5 0.5
Ks  0.8 0.8 0.8

newmtl light
Ka 1.0 1.0 1.0
Kd 1.0 1.0 1.0
Ks 1.0 1.0 1.0