There are two ways to preview and render 3D elements in Toon Boom Harmony. You can render your scene using the OpenGL preview, or render calling Autodesk Maya or 3Delight in the background.
If you do not set up a plugin to preview your model with Maya or your 3D software, the preview and rendering will be done using the OpenGL preview. The result will look flat and jagged, but it can be very handy while working and exporting shots for approval.
If you render a scene calling Autodesk Maya, you will get a smooth result with texture and lighting.