If so, then check to see if they are on 'edge polys' ...

There may be some misses not on edge polys that could be caught by scanning another actor as well, but when that's the case, then there will be some edge poly vertices missed as well.  In other words, if any of the missed verts are on edge polys, then set up to scan other actors.

One tricky issue is...

You don't really want to scan all the vertices where you already have valid hits again with the new actor, but you also don't want to write out the associated data again (they reference a different actor's poly/vertex indices).  So, you'd probably want some other means of identifying vertices that have already been resolved (before calling linecast_loop() with a new actor, maybe set all non -1 values to -2 and change the appropriate "if xpolys[n] != -1" tests to just look for >= 0 for valid data.

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