OpenGL Multipipe
Encyclopedia
OpenGL Multipipe is the default SGI solution for handling parallel rendering on a single desktop using multiple displays on Irix
and Linux. It first appeared in Irix 6.5.10 as a solution for creating desktops on SGI Onyx
Visualization Systems (their so called Reality Centers) which took advantage of multiple Raster/Geometry Managers in multiple pipelines. The package was originally composed of Xinerama, a Xinerama aware version of 4DWM (called omp4Dwm) and a backend server to handle and distribute all OpenGL threads to the various physical pipes called Transparent OpenGL (or tgl).
In SGI
parlance, a pipe (see Graphics pipeline
) is akin to a PCI Video Card connected to other cards that handle Geometry and/or Rasterization in a "pipeline" (hence the name and the relevant nature of OpenGL), somewhat similar to 3Dfx
's Voodoo Graphics card (though many considered the latter hackish and not at all a true pipe). Nowadays a pipe is solely on a single board and on a single chip (GPU). More to the point, a single SGI pipeline (e.g. InfiniteReality4) could be configured to have up to 8 Video Outputs, each with its own Raster Manager (or 4 with additional Texture memory and a Geometry manager). SGI's Implementation of Xinerama would transparently handle OpenGL on all display outputs (including multiple pipes), but usually offloaded all OpenGL calls to a blanket OpenGL API called transparent OpenGL(like running Xdmx
without Chromium).
Programming for a single display on multiple pipes was always possible in OpenGL using threads (and subsequently in Open Inventor
and OpenGL Performer
), making them "multipipe aware", but this proved challenging for scientists and arquitects who cringed on C/C++ multithreading. SGI decided to lighten the burden by developing a package that would encompass a halfway optimized solution for applications programmed for only one pipe via Multipipe.
OpenGL Multipipe was part one of a three tiered approach to escalate applications towards multipipe awareness. The second part was Multipipe SDK which provided a simple set of libraries that made an OpenGL application multipipe aware. The third was moving on to the multipipe aware OpenGL Performer. The latest versions of Multipipe include Xdmx as a better suited solution for multiple displays. Ultimately this solution would be superseded by working Xdmx, Xinerama and Chromium in tandem on linux graphics clusters. Programming multiple pipes in OpenGL would be facilitated by Equalizer or by a variety of SceneGraph Libraries.
IRIX
IRIX is a computer operating system developed by Silicon Graphics, Inc. to run natively on their 32- and 64-bit MIPS architecture workstations and servers. It was based on UNIX System V with BSD extensions. IRIX was the first operating system to include the XFS file system.The last major version...
and Linux. It first appeared in Irix 6.5.10 as a solution for creating desktops on SGI Onyx
SGI Onyx
The SGI Onyx, code named Eveready and Terminator , is a series of visualization systems designed and manufactured by SGI, introduced in 1993 and offered in two models, deskside and rackmount. The Onyx's basic system architecture is based on the SGI Challenge servers, but with the notable inclusion...
Visualization Systems (their so called Reality Centers) which took advantage of multiple Raster/Geometry Managers in multiple pipelines. The package was originally composed of Xinerama, a Xinerama aware version of 4DWM (called omp4Dwm) and a backend server to handle and distribute all OpenGL threads to the various physical pipes called Transparent OpenGL (or tgl).
In SGI
Silicon Graphics
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
parlance, a pipe (see Graphics pipeline
Graphics pipeline
In 3D computer graphics, the terms graphics pipeline or rendering pipeline most commonly refers to the current state of the art method of rasterization-based rendering as supported by commodity graphics hardware. The graphics pipeline typically accepts some representation of a three-dimensional...
) is akin to a PCI Video Card connected to other cards that handle Geometry and/or Rasterization in a "pipeline" (hence the name and the relevant nature of OpenGL), somewhat similar to 3Dfx
3dfx
3dfx Interactive was a company that specialized in the manufacturing of 3D graphics processing units and, later, graphics cards. It was a pioneer in the field for several years in the late 1990s until 2000 when it underwent one of the most high-profile demises in the history of the PC industry...
's Voodoo Graphics card (though many considered the latter hackish and not at all a true pipe). Nowadays a pipe is solely on a single board and on a single chip (GPU). More to the point, a single SGI pipeline (e.g. InfiniteReality4) could be configured to have up to 8 Video Outputs, each with its own Raster Manager (or 4 with additional Texture memory and a Geometry manager). SGI's Implementation of Xinerama would transparently handle OpenGL on all display outputs (including multiple pipes), but usually offloaded all OpenGL calls to a blanket OpenGL API called transparent OpenGL(like running Xdmx
Xdmx
Xdmx or DMX is the Distributed Multihead X Project. It acts as a proxy X server for multiple back-end X servers...
without Chromium).
Programming for a single display on multiple pipes was always possible in OpenGL using threads (and subsequently in Open Inventor
Open Inventor
Open Inventor, originally IRIS Inventor, is a C++ object oriented retained mode 3D graphics API designed by SGI to provide a higher layer of programming for OpenGL. Its main goals are better programmer convenience and efficiency.-Early history:...
and OpenGL Performer
OpenGL Performer
OpenGL Performer, formerly known as IRIS Performer and commonly referred to simply as Performer, is a commercial library of utility code built on top of OpenGL for the purpose of enabling hard real-time visual simulation applications. OpenGL Performer was developed by SGI which continues to...
), making them "multipipe aware", but this proved challenging for scientists and arquitects who cringed on C/C++ multithreading. SGI decided to lighten the burden by developing a package that would encompass a halfway optimized solution for applications programmed for only one pipe via Multipipe.
OpenGL Multipipe was part one of a three tiered approach to escalate applications towards multipipe awareness. The second part was Multipipe SDK which provided a simple set of libraries that made an OpenGL application multipipe aware. The third was moving on to the multipipe aware OpenGL Performer. The latest versions of Multipipe include Xdmx as a better suited solution for multiple displays. Ultimately this solution would be superseded by working Xdmx, Xinerama and Chromium in tandem on linux graphics clusters. Programming multiple pipes in OpenGL would be facilitated by Equalizer or by a variety of SceneGraph Libraries.
See also
- XdmxXdmxXdmx or DMX is the Distributed Multihead X Project. It acts as a proxy X server for multiple back-end X servers...
- A multi node X server - Chromium (computer graphics) - Distributed OpenGL API for clusters