Frequently Asked Questions

This FAQ provides general information about OpenGL Multipipe™. For version-specific information, please refer to the release notes associated with the particular version of interest.

What is OpenGL Multipipe?
OpenGL Multipipe provides a layer by which single-pipe applications can run transparently in multipipe configurations. Both OpenGL® and X applications are supported.

What version of IRIX® do I need?
The operating system prerequisite for OpenGL Multipipe™ 2.3.2 is IRIX® 6.5.22 or later plus patch 5448 for Silicon Graphics® Onyx4™ systems and IRIX® 6.5.18 for all other Silicon Graphics® visualization systems. The operating system requirement for OpenGL Multipipe™ 1.4.2 is IRIX 6.5.18 or later for all systems except the Silicon Graphics Onyx4 which is not supported with OpenGL Multipipe 1.4.2.

Why is OpenGL Multipipe 1.4.2 still available, and what are it's requirements?
OpenGL Multipipe 1.4.2 is still available for those users of multi-pipe SGI systems which have not upgraded to the latest versions of IRIX. OpenGL Multipipe 1.4.2 requires as a minimum SGI® IRIX® 6.5.15 or later. Users are encouraged to upgrade to OpenGL Multipipe 2.3 since it supports many new advanced features, and availability and support for 1.4.2 is planned to end at the end of CY2004.

What hardware is supported?
Platforms supported include Silicon Graphics Onyx4, SGI® Onyx® 3000 series, SGI® Onyx® 300 series, Silicon Graphics® Onyx2®, Silicon Graphics® Onyx®, Silicon Graphics® Tezro® and Silicon Graphics® Octane2™. Only R10000® and later processors are supported.

Does OpenGL Multipipe replace OpenGL Performer™, OpenGL Multipipe™ SDK, or the need for custom multipipe-aware applications?
No. SGI provides three levels of scalability. Transparent scalability with OpenGL Multipipe, toolkit scalability with OpenGL Multipipe SDK, and high levels of scene graph scalability with OpenGL Performer. Applications written with OpenGL Multipipe SDK or OpenGL Performer will typically show higher levels of scalability than those that run transparently with OpenGL Multipipe, but require additional software development. OpenGL Multipipe provides a convenient mechanism for running unmodified single-pipe applications on multipipe configurations and on the large displays that often accompany such machines. This is important to a wide variety of users who have standard single-pipe commercial applications or licensing issues or who may not have source code or developers available. A certain overhead is incurred in running single-pipe applications under OpenGL Multipipe. Developers interested in using the resources of multipipe hardware for maximum performance will develop their applications to be "multipipe aware" rather than use an application-transparent solution.

Can I mix multipipe and single-pipe applications?
Yes, both can run concurrently. There is no overhead introduced on multipipe applications running with the OpenGL Multipipe layer active. These multipipe applications can be run in "aware mode," effectively bypassing the transparent multipipe layer. A window manager solution provided with the distribution is needed to allow applications running in aware mode to be under window manager control. Without the window manager solution, applications that are run in multipipe-aware mode will not be under window manager control.

Does OpenGL Multipipe provide performance scaling?
OpenGL Multipipe can provide high amounts of scaling for pixel fill limited applications, and can provide low to moderate amounts of scaling for geometry limited applications. The impact of features such as viewport clipping, geometry culling and display list breakdown are very application and data set dependent, so it is impossible to predict specific results.

Are there any limitations on the size of the display?
The single logical display in OpenGL Multipipe has a theoretical limit defined by the X-server of 32,767 x 32,767 pixels, but for obvious reasons this resolution has not been tested. Single pipe applications can scale to the maximum resolution using both X-windows and OpenGL if they are using the recommended DMX implementation. If the installation has chosen to use Xinerama as the underlying technology, the single pipe limiations for OpenGL applications are limited to 3840x3840 on InfiniteReality®, InfinitePerformance™ and VPro™ family graphics, and 4096x4096 on Silicon Graphics Onyx4 with UltimateVision graphics. IN all cases, these windows can be located anywhere within the single logical display.

Are all X extensions supported?
No, because some X extensions are inherently nontransparent (e.g., Xvc). For these extensions to work correctly, an application that uses them must be started in multipipe-aware mode. A list of supported X extensions is included in the Xdmx(1) and Xinerama(1) man pages

Are all OpenGL extensions supported?
OpenGL Multipipe is targeted at supporting OpenGL 1.4 for Silicon Graphics Onyx4 systems plus many of the ATI extensions. Support of SGI Onyx 3000 family, SGI Onyx 300 family, Silicon Graphics Onyx2, Silicon Graphics Tezro, and Silicon Graphics Octane2 systems is targeted at base OpenGL 1.2.

Does OpenGL Multipipe support IRIS GL™?
No, OpenGL Multipipe does not support IRIS GL. Therefore, applications such as Showcase™ and Snapshot, which are based on IRIS GL, are not supported.

How is OpenGL Multipipe different from OpenGL Multipipe SDK?
OpenGL Multipipe and OpenGL Multipipe SDK are very different. OpenGL Multipipe is an IRIX OS-level utility that allows an application to utilize multiple pipes, even though it was originally written for use with a single pipe. OpenGL Multipipe SDK is a programming interface for the development of "multipipe" applications, i.e., applications specifically designed to run in multipipe environments. Applications written with OpenGL Multipipe SDK will, in general, provide better multi-pipe scalability than single-pipe applications run transparently under the OpenGL Multipipe environment.

What screen configurations does OpenGL Multipipe support?
OpenGL Multipipe supports planar 2D arrays. In planar configurations, screens need not conform to a regular grid; horizontal and vertical screen overlapping can be enabled for projection systems that perform edge blending.