The scene appears to load as usual, but when rendered, rays enter the shape but don't exit. This is because the normals are pointing to the inside. There is a validity algorithm that attempts to create all shapes with normals facing outward, but unusually shaped shapes may be created with the normals facing inward. To flip the normals choose properties from the shape menu and select the shape in the scene. Now press the flip normals button.
Nothing appears to happen, but try rendering.
This time it will render as expected. The benefit of surface normals, besides the speed enhancement is that you can see out of objects but not in. If for example you modeled a camera, you could put the scene's camera inside. If the camera ever saw itself in the mirror, it would look like a camera rather than nothing. Return to main page.