In this mode, the rendering engine is expected to render the objects specified by the "Scene"context attribute and periodically send image data back to Softimage using the RendererContext::NewFrame and RendererContext::NewFragment calls.
The renderer can also write out this rendered data to disk, depending on the state of the "FileOutput"context attribute.
If the renderer supports rendering multiple render channels, the render channel to give back as fragment data to Softimage is specified by the return value of the RendererContext::GetDisplayFramebuffer call.
The renderer should also inform Softimage of the current state of the render by calling the RendererContext::ProgressUpdate call. It is best to keep the short message under 30 characters or so. The long message can be up to 100 characters or whichever fits best in the render preview window, assuming a PAL or NTSC render.
