The Jack-in-the-Box application grew out of a desire to create something fun and active in a virtual environment, and was originally designed as an element in Jim Barr’s The Great Sandini Virtual Reality Circus.

This application, like a shooting gallery, lets the CAVE™ guest shoot missiles at a moving target. The target is a Jack-in-the-Box that springs up, then bobs crazily waiting to be hit. The “wand” is used to shoot snowballs at the jack heads. When the jacks are successfully hit they complain.

This application uses a grab-bag of graphical techniques to make the jacks look and behave dynamically and realistically. The body is a single spring chain length. The head bobbing is achieved using a quaternion aligned along the last few lengths of the spring chain. The head is a displaced sphere; the displacement is a function of the green component of an RBG image. The image is also texture mapped onto the deformed sphere. The image has two functions - providing the shape and color of the head. The snowballs and yellow “sparkles” are based on particle systems.