image/svg+xml uses algorithms of Prs3D and StdPrs packages to Class AIS_Shape Compute() create Graphics3d structure Topological Object StdPrs and Prs3d packages Contain various algorithms to transform object structures into Graphics3d structures Declares Compute() method Deferred class AIS_InteractiveObject uses inherits Object presentation Class PresentationManager3d calls Compute() method of AIS_InteractiveObject to obtain Graphics3d structure deals with calls Compute() Creation of AIS_Shape Creation of topological object