I am completely new to Assimp, so please accept my apologizes
if the following has already been reported or is mentioned in red
and upcase in the documentation.
I played around with the viewer and noticed the following bug
with a COLLADA file (attached, as well as the screenshot).
While the model is seemingly correctly loaded, rendered and
shaded, it completely falls apart when selecting
Tools>Hard normals or Tools>Smooth normals,
Getting back to Tools>Original normals doesn't fix things back,
and the model basically has to be reloaded.
Besides this, from what I've seen so far Assimp is a neat
library. Keep it up the good work!