<World>
   <Camera eye="0, 100, 300" look_at="0,0,0" fov="70" />

   <ShaderGroup>float Kb 0.5; shader furnace layer1;</ShaderGroup>
   <Background />

   <ShaderGroup>color Cs 1.0 1.0 1.0; shader matte layer1;</ShaderGroup>
   <Sphere center="  0,0,0"        radius="30" />
</World>
