I read and tried over and over but still can't understand what's the purpose of that function. Could someone explain? Thanks in advance.

It's just a helpful way of selecting different sets of vertices. Such as for an "arm", or "head", etc...

It appears to break a model up into groups of polys so that you can select and work with them easier. If you select a bunch of connected polys, then use the group tool, you can turn on the "select connected" tool and it will only select that group of polys. I've found it handy when a model starts to get complex, and you want to use the "hide unselected" tool to work only with the polys in the group.

Mark

Thanks. I understand the group tool to assign select polys in groups. But still not quite understand "Arrange in Groups" option, once select that option nothing happen and everything unselect.

From the manual:

Quote:

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In groups mode, automatically arrange the selected part of the mesh into triangle groups created from connected parts of the skin mapping. Normally, the groups correspond to the different body parts.

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I can't figure out the meaning of above quote, could you give some examples how to use the "Arrange in Groups"?