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

   <ShaderGroup>
      param float scale_s 20;
      param float scale_t 20;
      param color Ca 0.1 0.1 0.1;
      param color Cb 0.5 0.5 0.5;
      shader checkerboard tex;
      shader matte layer1;
      connect tex.Cout layer1.Cs;
   </ShaderGroup>
   <Quad corner="-200,0,0" edge_x="400,0,0" edge_y="0,400,0" /> <!-- Back -->
   <Quad corner="-200,0,0" edge_x="0,0,400" edge_y="400,0,0" /> <!-- Botm -->


   <ShaderGroup>
     param string dist "default" [[int lockgeom=0]];
     shader microfacet_test layer1;
   </ShaderGroup>
   <Sphere center="-60,30,120"        radius="30" />
   <ShaderGroup>
     string dist "ggx";
     shader microfacet_test layer1;
   </ShaderGroup>
   <Sphere center="  0,30,120"        radius="30" />
   <ShaderGroup>
     param string dist "default" [[int lockgeom=1]];
     shader microfacet_test layer1;
   </ShaderGroup>
   <Sphere center=" 60,30,120"        radius="30" />
   
</World>
