This chapter describes how to use the functions provided by the graphics
library to manipulate and animate Graphic Elements (also called GELs).  It
is divided into six sections:

  * An overview of the GELs animation system, including fundamental terms
    and structures

  * Explanation of simple (hardware) Sprites and an example showing their
    usage

  * Explanation of vsprites and an example showing their usage

  * Explanation of bobs and an example showing their usage

  * Discussion of topics that apply to all GELs such as collision
    detection and data structure extensions.

  * Discussion of animation, using animcomps and animobs and an example
    showing their usage

 about the gels system 
 using simple (hardware) sprites 
 using virtual sprites 
 complete vsprite example 
 vsprite advanced topics 
 using bobs 
 collisions and gel structure extensions 
 animation with gels 
 function reference