surface
candy_stripes(float    Kfb = 1;
            float     trans = 1;
            float    gap = 0.2;
            float    width = 0.1,
                    offset_t = 0.0,
                    tangent = 0.5; /* [0, 10000] */
)
{
  
color surfcolor = 1;
float i;
float offset = offset_t;
if(tangent > 0)
    while (width + offset > -tangent)
    {
    offset -= gap;
    }
    
for (i = offset; i < 1; i += gap){    
if(t >= tangent * s + i && t <= tangent * s + i + width)
    surfcolor = color (cos(t), 0, sin (s));
}
  
Oi = Os * trans;
  
Ci = Oi * Cs * surfcolor * Kfb;
}