Try the openGL version of this applet here.

Animation control
b - start/pause the play the 3 phase animation
a - jump to start of the animation
s - move one step back in the animation
d - move on step forward in the animation
f - jump to end of the animation

Drawing control (toggles)
t - draw twist operators
g - draw grid
p - draw pinned points
l - draw laplace vectors
y - draw both images half transparent
v - exchange images
x - switch to/from whole animation mode to single (control only one step)

Data control
1,2,3 - load one of the 3 twist sets
4,5,6 - store the current twist set as 1,2,3
SPACE - clear the twists (and create a dummy twist)

Press 't' to see and manipulate the twists. Drag the control points and see what happens. It's very easy. If you click on a twist while holding the CTRL key you delete it. If click somewhere else you will create a new twist. Drag to position the second point. If you press CTRL when creating a twist, you create a pure translation 'twist' (don't forget to release the CTRL-key before you release the mouse button, otherwise you imediately delete the twist again).

Source code: p3d SaveLoad main twist

Built with Processing