Version Info: Blender 2.41 built on 2006-01-23 version win32 dynamic
(Also see my recent post on the “Blender Python & Plug-ins” forum)
I’ve constructed a solid (i.e. capped) cylinder by extruding a circle mesh along the Z-axis.
I’ve carefully set all the cap faces to be “solid” and the curved vertical to be “smooth”. Everything renders OK in the internal renderer (i.e. curved surfaces are smooth and caps are flat).
When I export the mesh data, I find that the normals of the cap faces have been taken into account when determining the smoothed normals of the curved part of the cylinder. Ordinarily I would expect the cap faces to be ignored when smoothing the other normals, i.e. the smoothed normals should always end up parallel to the XY axis but, on examining the exported data, they’re not.
The “smooth” status of all the faces appears to be correct but the faces marked as solid have definitely been taken into account when smoothing the normals of the smooth faces.
Did my explanation make sense? This strikes me as a bug…