Which is the maxium numbre of polygons for a model?
There may be a limit of 65535 polygons or vertices in a single model.
And Why does the models lost its smothness whe I simply import and export the model without modify it whit Blender?
Depending on the modeling software, an import followed by an export may cause the normals to disappear or get recomputed, causing the surfaces to appear faceted.
Cogs is a little fragile in its support of .obj files. If there are multiple meshes or any unusual tags in the file, the load may fail. Ideally, lines in the file should only start with v (vertex), vt (texture coordinate), vn (normal), and f (face).
Founder, Lazy 8 Studios