I have two problems need to be solved:
First, I wanted to select all the border edges of UV map(for every shell).
This is my way:
1) Select texture shell border on the select menu in UV Texture Editor. All UV points on the border are selected. See Fig. 1
2) Then convert the UV points to the continued edges. As you see, not only the border edges, but also the edges share these uv points are selected. Fig. 2
3) So I got the vertex lists(from UV points) in the first step and the continued edges lists in the second step. Check that whether the two vertices of every edge in the continued edges lists is included in the vertex lists. If not, remove the edge from the continued edges lists.
But, this way become useless in one case: Triangle. Fig. 3
In figure 3, these edges under the question mark can't be removed since all the vertices are included in the vertex lists.
Next, I found that the edge must be the map border only if the two vertices of one corresponds more than two UV points (except model border, which can be listed in other way). The troublesome edges finally can be removed.
But I don't think this is a good way since it's take many calculation to get the border edges.
So my first question is that, is there good idea from anybody?
By the way, I noticed that it is no waste time to highlight the texture and model borders in Maya using polygon display menu, no matter how complexity the model is. I think that maybe Maya stores these datas in nodes, all need to do are just read and show. And I checked many Mel commands and API functions but found nothing.
Naturally the second question, is there any Mel or API which can read or store the border edges datas? or how to explain the too small time between clicking menu and showing borders?