I believe I found a bug.
I loaded the very awesome 75174p01c01.dat and rotated it such that one transparent wing overlaps the other transparent wing.
From a side view, I would expect the back wing to be visible through the front wing (both wings are transparent) however this is only true when viewing from one side, not the other:
View from right side of dragon (as expected):
View from left side of dragon (back wing invisible behind front wing):
I loaded the very awesome 75174p01c01.dat and rotated it such that one transparent wing overlaps the other transparent wing.
From a side view, I would expect the back wing to be visible through the front wing (both wings are transparent) however this is only true when viewing from one side, not the other:
View from right side of dragon (as expected):
View from left side of dragon (back wing invisible behind front wing):