Spherical Sketchpad

There is now a new version of this program called Spherical Easel. Spherical Easel has some additional features that may make it more attractive.

Here is a tool, which is very much like Geometer's Sketchpad, for studying geometry on the sphere. You may define points and lines and relationships between them by clicking and releasing the mouse inside of existing points. When a point is subsequently moved, the relationships between the diagram's elements are preserved.

Detailed documentation will soon be available. For now, please note the following features:

In general, mouse operations such as clicking and dragging operate on points on the front portion of the sphere. To access points on the back of the sphere, hold down the control key.
When drawing a line segment, holding the Shift key fixes the great circle on which the segment is drawn. In particular, this allows one to draw segments whose length is greater than pi.
To access the menu operations, one should first select the menu item and then follow the instructions given at the bottom of the diagram.

Spherical Sketchpad is created by David Austin and Will Dickinson. Please let us know if you find any problems or if you have comments.

Enjoy Spherical Sketchpad!