Yves Pelletier, the maker of GifBuilder and numerous scientific educational apps, has announced the availability of YP Shadow 1.0. YP Shadow is an educational program helping students understand the nature and behavior of shadows. According to Yves Pelletier:
YP Shadow simulates a light source casting the shadow of an opaque body on a screen. With the mouse, the user can easily move and resize the light source, the opaque body and the screen. YP Shadow draws the rays of light used to mark the boundaries of the umbra and the penumbra, and it displays the shadow as it appears on the screen. A grid can be used to measure the shadow's size.
YP Shadow is available as shareware for US$18. You can find more information at the YP Shadow web site.