The polygon editor in the middle allows you to drag the corner points of the doubling cycle to turn it into a Lang polygon. Red dotted lines between corner vertices represent vertices whose distance is less than their corresponding distance in the tree, thus violating the definition of a Lang polygon. Once all of these constraints are removed, you will see only the green polygon.
Note: In the current version it is possible to invert the ordering of the polygon nodes such that the walk of the tree corresponds to a clockwise, rather than counter-clockwise walk of the polygon. In this case the vertex labels will fall inside the polygon rather than outside it and the output is undefined, since our implementation assumes that the walk of the inner face is counter-clockwise. Future updates will address this limitation.
Once you have a polygon defined, drag the sweep slider above the the polygon editor to view the sweeping process as it generates the crease pattern. You can continue to edit the vertices of the polygon and see the crease pattern update live. If, however, you modify the tree, you will need to click on the "››" button to generate a new doubling cycle for the tree.
The rightmost window is the 3D visualization. You can click+drag the mouse in this window to change the viewing angle.
Please note: it takes some time to load the required libraries.
Requires Java 1.6. Safari versions before 5.1.3 have issues loading the Applet. Please use Google Chrome or Firefox if you don't have Safari 5.1.3.