surface
orange_cross(float    Kfb = 1;
            color tint = color (1,0,0);
            float     trans = 1;
            float    cutoff = 0.5;
            float    top = 0.3;
            float    bottom = 0.7;
            float    left = 0.3;
            float    right = 0.7)
{
  
color surfcolor = 1;
  
if( t >= top && t <= bottom )
    surfcolor = color(1.0,0.5,0.0);
if( s >= left && s <= right )
    surfcolor = color(1.0,0.5,0.0);
  
Oi = Os * trans;
  
Ci = Oi * Cs * surfcolor * Kfb;
}