The PEX extension to the X protocol provides support for 3D graphics applications. Using the PEX X server module, NCD terminals can display 3D drawing applications written for PEX. 3D applications provide such features as 3D objects, transformations, floating-point color, and lighting.

Applications that use PEX include 3D drawing programs, CAD (computer-aided design) programs, and scientific visualization programs. When considering 3D clients to be run on NCD X terminals, make sure they are based on PEX. Only applications that generate the PEX protocol can access the PEX functional extensions in the PEX server.

As with the core X protocol, software for running PEX applications is required on the terminal and on the host computer where the application is running.

The PEX acronym stands for PHIGS Extension to X. PHIGS was the original API (application programming interface) for PEX. Since the origin of PEX, other APIs have been implemented and PEX is no longer based solely on PHIGS.

The PEX X Server Module

The PEX X server module allows you to display PEX images along with standard X images on your NCD terminal.

The PEX module supports PEX protocol versions 5.0 and 5.1. The PEX module supports all of the subsets of PEX: immediate mode (the Renderer Subset), structure mode (the Structure Subset), and workstation mode (the PHIGS Workstation Subset). These subsets provide a variety of 3D and 2D graphics capabilities.

Data can be rendered immediately as it is transmitted to the terminal (immediate mode rendering) or it can be stored as data in the terminal (structure mode), where it can be quickly updated and re-rendered. Workstation mode is similar to structure mode and provides additional control of scene updating.

The PEX module includes two other X extensions:

• MBX (the MultiBuffer Extension to X)-Provides an invisible drawing buffer for rendering one scene while another scene is displayed. This enables clients to provide smooth animation with little effort.
  

• XInput (the Input Extension to X)-Provides support for the sophisticated input devices required by some PEX clients. In NCDware, Summagraphics-compatible digitizing tablets and the Logitech 3D mouse are supported.
  

The PEX module provides both terminal configuration parameters and user preference parameters for PEX. "Setting PEX Configuration Parameters" describes the parameters in detail.

PEX Fonts

The PEX module uses stroke fonts, which are scalable fonts defined as coordinates of line segments. The fonts required by PEX are built into the X server, so no additional font paths or font definitions are required. The PEX fonts available in NCDware are roman (a proportionally spaced font) and roman_m (a monospaced font).

The same two fonts are supplied on NCDware distribution media as downloadable font files. All fonts in the NCD PEX font format have filenames with the .phont suffix. The two font files available in NCDware are named Roman.phont and Roman_M.phont. These fonts are normally installed in the /usr/lib/X11/ncd/fonts/PEX directory during software installation.