(x,y,t,&r,&g,&b) // Fake sphere mapping.

// Get distance squared from centre.
d = x * x + y * y;

if (d < 1) {

   // Calculate texture coordinates.
   u = +(sin(x) / cos(d)) / pi + (t / 10);
   v = -(sin(y) / cos(d)) / pi + 0.5;

   // Get picture dimensions.
   t_w = 0;
   t_h = 0;
   getpicsiz(t_w, t_h);
   
   // Look up pixel from texture.
   pic(
      u * t_w,
      v * t_h,
      r, g, b
   );

   // Apply crude shading.
   shading = sin(x + t / 2) * 64;
   
   r -= shading;
   g -= shading;
   b -= shading;

} else {

   // We're outside the bounds of the
   // sphere, so return black.
   r = 0;
   g = 0;
   b = 0;
   
}