Yuku free message boards

ok, only one thing found (btw, this is (luckily) collada 1.4 (better) not 1.3, in case sbody wonders), is that , as was fearing, the no need of edgesplit is nothing magic: creases are actually broken (like when UVs are not able to keep in 3d as 2 separate vertices by an importer, but in this case, with normals creases) , that is, 2 vertex in those edges. This can be ok, but for games, and othe realtime 3d, or internal work (rigging, export with certain other package plugin...) can be a prob. The funny thing is, is quite convenient so for some cases, but not for others: An option in exporter to not break there would be nice, but am fearing is more a matter of a needed collada Blender importer setting, than sth our exporter can control...
Dunno if select/non-manifold, mark as sharp (doing with every object is there's more than one, or many) (in blender) , then "remove doubles", add edgesplit modifier, unmark in it "from angle", leave selected "marked as sharp", will work in regular cases...It worked here in a simple single test... In most cases rebuilding the normals creases by hand would be tedious... An OBJ imported, adding edgesplit modifier and done mentioned trick, wont force the split of vertices (until you apply modifier) which is, well, convenient in several cases.

yep, I have read that since eons, but the thing is more a matter of certain exporters, and certain workflows.

That is, while I was helping with blender's x export (testing, usage, probs, etc) long ago in its beguinings, when was not included in distributions, duped vertexes meant a prob during export(mainly related with weights in game characters). A matter more of how some exporters deal with stuff. And this also happens with some max exporters. At real time, yep, it's treated like you say, but while you work, there are advantages (and some problems) of not having a duped vertex in your viewport at those edges. There are several tools that deal like this, indeed, blender does not internally, but till you apply the modifier, you work in the way I say that has some advantages for several operations. This is how it works in Max when you apply "smooth groups".(you can try this in that one, sharp edges vertexes are single ones)

not in game engines, as you said, but I recall several probs with *.x and some other format importer into the engine, as well as exporters issues in these 2 tools.

Besides, if you port the info like in obj-blender, that is, not mesh broken, you can add the modifier -in blender case- and choose to actually split, or not, not having to recreate edge creases manually...But keeping the option of unbroken mesh. More options.
I know about the UV thing, and indeed, whenever you export a UVed *.3ds, will break the mesh in uv seams. That is ok for most engines, not so ok for several package workflows, or importers/exporters. 3ds is a uber old format, OBJ imported into many tools will not break the mesh and still keep normals creasese. Wether if it internally is or not a real broken mesh, while it doesnt wreck some workflow, and doesnt mess some exporter, am ok with it. But to me, an unbroken mesh, with the edges creases available so you can split with a button touch, is a more flexible option...