pointlight light1 void 0 0 0 1 1 1

lambertian red   void 1 0 0
lambertian green void 0 1 0
lambertian blue  void 0 0 1

sphere s1 red   500   200  -100   200
sphere s2 green 400  -100  -50    150
sphere s3 blue  600     0   200   250