Computersight -

PHIGS+ is an advanced graphics standard of PHIGS. PHIGS+ works in the same manner as PHIGS. PHIGS+ is used to overcome the problems in PHIGS.

PHIGS (Programmer’s Hierarchical Interactive Graphics Standard) is an API standard for rendering 3D computer graphics. We can say PHIGS is a graphics system and language used to create 2D and 3D images. PHIGS is a device-independent interface between the application program and the graphics subsystem. It manages graphics objects in a hierarchical manner so that a complete assembly can be specified with all of its subassemblies.

In PHIGS, displaying graphics on the screen is a 3-step process:

1. The model would be built into a Central Structure Store.
2. A workstation would be created and opened.
3. Finally, the model would be connected to the workstation. At this point, the workstation would immediately render the model, and any future changes made to the model would instantly be reflected in the workstation view.

PHIGS originally lacked the capability to render illuminated scenes, and was superseded by PHIGS+. PHIGS+ works in the same manner, but added methods for lighting a 3D scene, and it referred as PHIGS PLUS. PHIGS+ also introduced more advanced graphics primitives, such as NURBS surfaces.