PHIGURE has several functions for defining views in addition to the PHIGS viewing functions. These functions are complementary as they call the following PHIGS functions peval_view_ori_matrix , peval_view_map_matrix3 , and pset_view_rep to define a view.
PHIGURE keeps the same concept of identifying a view by a view index and a given workstation. A view may also be defined by PHIGURE using a single function with intuitive parameters such as observed point, zoom factor, etc.
Programmers may choose a view function from a set of several functions for defining a view in 2D or 3D. (function defining a view by angles, points, etc.).
As a view is identified by a workstation and view index, all PHIGURE view definition functions start with the 2 parameters ws_id and view_ind
The next parameter is the point observed by a fictitious observer. It coincides with the center of the viewport used. (see viewport definition)
This point corresponds to the PHIGS view reference point. As in PHIGS it is defined in WC space. Furthermore, if the application displays structures grouped in a scene, user data is normally between 0 and 1 in WC space after transformation by traversal (see scene transformation).
As a result, the coordinates of the point observed should normally be between 0 and 1 whatever the the user limit coordinates (see domain).