First up, the UV stitching get corrpted.While the UV co-ordinates themselves remain in place, some of their welds get broken.You can see in the following image, the UV edges(green lines) before export, and after export.
WHile the co-ordinates themselves remain intact, unstitched vertices are slower to render.It also complicates the second problem, which is that the mesh becomes broken along the UV edges.You can see in the following image that the top of the mesh is one single element, however after export it has been broken into multiple elements.
To avoid this, you need to save the UV layout, and export the model with "Preserve MAX's Texture Coordinates" disabled.
To save the UV layout, first apply an Unwrap UVW modifier to the mesh, then in the Parameters rollout, click 'Save'
Upon importing your model, apply the Unwrap UVW modfier again, and load the UV file you saved.
If you follow this procedure, you will not encounter mesh division due to UV mapping, and your UV seams will also remain intact.
This post has been edited by key0p: 18 March 2005 - 09:22 AM