• the only object in the scene is the generic sphere
• the only attribute of the generic sphere is an assigned (emissive) color
  
• the camera is set up
  • (*10) at position (eye_x, eye_y, eye_z),
    
  • (*10) looking at point (look_at_x, look_at_y, look_at_z), with
    
  • the original up-direction for the camera being <0,1,0>.
    
    
• speed-up has been accomplished by more wisely computing the ray's direction, for each ray.