void ufoProcessRenderLine( ufoProcess process_instance, int x1, int x2, int y);
One of these three functions must be supplied. It calls every pixel, line or rectangle, respectively, within a single render pass. On the last render pass, (which is the only render pass by default–unless multiple passes have been set), the region supplied in the arguments should be rendered to the UFO process outputs.
If the current render pass mode has been set to ufoPassVertical using ufoProcessSetRenderPassMode then the argument x and y values are swapped.
Autodesk Softimage v7.5