PHIGS (Programmer's Hierarchical Interactive Graphics System)
PHIGS is an API standard for rendering 3D computer graphics. During the 1990's OpenGL became a more popular 3D API for professionals, and it still is today. PHIGS remains to be widely used in the film industry. Open PHIGS uses OpenGL for rendering graphics rather than implementing it's own abstraction layer to the graphics hardware, or using the PHIGS Extension to X (PEX). The reason for doing so is that today every graphics card manufacturer provides their own OpenGL implementation, which takes full advantage of the accelerated drawing capabilities in the hardware. PHIGS is a higher level API than OpenGL that works with a hierarchical scene graph. Models are built up in a Centralized Structure Store (CSS), a database containing the drawing primitives and their attributes (color, line style, etc.). CSSes cand be shared among a number of views, known under PHIGS as a workstation. PHIGS is defined by the ISO standards ISO/IEC 9592 & 9593. Open PHIGS provides a library for C.