Birds of a feather and strange bedfellows defend OpenGL

Misunderstandings, a lack of candor in some quarters, and slow driver releases confuse end users

By Kathleen Maher

It must amaze Microsoft that what they said at their development conference, WinHec, a few years ago has come back to haunt them. Earlier in the development cycle of Vista, Microsoft’s engineers floated the idea of abandoning support for OpenGL or supporting it through Direct X. Microsoft’s own engineers eventually nixed the idea early but the trouble it caused lives on.

Contrary to speculation, and let’s face it, the less fun interpretation, Microsoft’s motivation was not really all that evil. The software engineers wanted to all the heavy lifting for graphics control out of the hardware kernel. As the accompanying diagram of the OpenXP architecture illustrates, the operating system environment is separated into two major areas, the user mode which involves communications between applications and to the APIs and the kernel mode which communicates directly with the hardware. With most of the graphics control located in the kernel, a problem with the graphics subsystem crashed the whole system presenting the hapless user with the cursed Blue Screen of Death.

One solution suggested by the Microsoft engineers was to run OpenGL on top of Direct3D to get to the hardware. No doubt, the idea no doubt made sense to engineers hard at work on revamping a more efficient Windows APIs and they were, by all reports, very pleased with the work done on Direct3D. At any rate, cooler heads did prevail, and OpenGL has the same access to the WDM as Direct3D as shown in the block diagram of the Vista system on the left.

Nevertheless, confusion persists over OpenGL’s performance in Vista especially for people in the CAD industry. Early benchmark tests performed by gamers were showing terrible performance for OpenGL applications on Vista according to the SPECmarks and nothing gets attention like bad news. Some interpretations, rather than questioning the drivers or the type of hardware used in the tests, suggested instead that OpenGL was no longer fully supported by Windows Vista. At a recent CAD and PLM conference, COFES (the Congress on the Future of Engineering Software), a sizeable number of users were confused about the role of OpenGL within Windows Vista. (And, there was a sizeable population that didn’t even know or much care that there was a controversy).