This check box is a convenient option which, when disabled, lets you export to RIB without saving the RIB code that you have entered into the field.
The Text field is where you enter your RIB code. The code will be written to the RIB files as is with one exception: A common use of custom RIB replacement to load external RIB archives. When these contain an animation each file name usually contains a frame number. Upon export, the default RIB Container tag replaces any occurrence of "@” characters with the frame number. The frame number is padded with 0 so that it has exactly as many digits as there are "@” characters in the original string. So, in order to include a sequence of RIB archives into your scene you can then just type the following into the Attribute Manager’s text edit field:
At RIB Generation time the @@@@ will be replaced by the current frame number, so the line written to the RIB file for frame 28 would read as follows:
The Position setting gives you some additional control over the exact location of your RIB in the file. You can select from three options:
Before: The RIB code will be written prior to the actual object, but after any attribute definitions applied to that object (e.g., visibility, color, shaders, etc.). This lets you override certain attributes or add your own.
After: Puts the code after attribute settings and geometry definition of the object, but before any objects further down the hierarchy are written.
Replace: Replaces the object with your code.
Example: A simple proxy object in the scene can be replaced in the RIB files by a ReadArchive call to the fully detailed object as RIB archive. Attributes like visibility, surface and displacement shaders will still be written, so they can be inherited by your own objects.