OpenGL Interface in Windows NT 3.5 (124034)
The information in this article applies to:
- Microsoft Windows NT Workstation 3.5
- Microsoft Windows NT Server 3.5
This article was previously published under Q124034 SUMMARY
This article defines and explains the OpenGL interface that is available
and can be implemented in Windows NT version 3.5. The following topics are
covered in this article:
- Definition of OpenGL
- Standards Organization
- Architectural Overview
- New API Functions
- Platform Compatibility
MORE INFORMATIONDefinition of OpenGL
OpenGL is a software interface that allows graphics programmers to create
high-quality three-dimensional color images with graphic effects such as
shading, lighting, texture mapping and matrix transformations. OpenGL
branched from the powerful IRIS GL graphics interface that runs on Silicon
Graphics' IRIS GL workstations. While IRIS GL is platform- specific, OpenGL
is an open standard designed to run on a variety of computers and a variety
of operating systems.
Standards Organization
The OpenGL standard is maintained by an independent group called the
Architectural Review Board (ARB), which meets on a quarterly basis and
includes representatives from DEC, IBM, Intel, Silicon Graphics and
Microsoft. The ARB governs both the features and conformance testing of
OpenGL.
Architectural Overview
In Windows NT, GDI functions initiated from a graphics application are
processed by the dynamic link library (DLL) GDI32.DLL on the client side.
The GDI request is then transmitted to WINSRV.DLL on the server side. This
in turn dispatches the requests to the video display driver through the
device driver interface (DDI) layer called Win32 DDI.
OpenGL functions are processed the same way as GDI functions with a few
additions. The functions are sent to OPENGL32.DLL on the client side for
graphics processing. OpenGL requests are packaged and transmitted to
WINSRV.DLL on the server side. The OpenGL requests are then dispatched to
the video display driver through the hardware- specific DDI layer. The
hardware-specific DDI resides alongside the Win32 DDI and can be obtained
through a vendor that manufactures an OpenGL accelerator. If the
accelerator is obtained, an additional software module known as the OpenGL
Installable Client Driver is provided, which resides between OPENGL32.DLL
and WINSRV.DLL.
New API Functions
OpenGL is basically a library of API functions for performing three-
dimensional drawing and rendering. OpenGL adds five new categories of API
functions to Windows NT. They are as follows:
- 115 OpenGL functions (prefixed with the letters GL)
- 43 utility functions (OpenGL utility library prefixed with GLU)
- 31 auxiliary functions (OpenGL auxiliary library prefixed with AUX)
- 6 WGL functions (prefixed with the letters WGL)
- 5 new Win32 API functions (no prefix)
Platform Compatibility
OpenGL functions are completely portable from one platform to another.
However, porting an OpenGL application from one implementation to another
involves some rewriting to accommodate differences in each platform running
Windows NT version 3.5. In other words, OpenGL programs are not compatible
at the binary level but are compatible at the source code level. Therefore
these programs written and tested in one platform must be recompiled in
others for it to run properly. Currently, OpenGL for Windows NT runs on
Intel, Alpha, and MIPS platforms.
The third-party products discussed here are manufactured by vendors
independent of Microsoft; we make no warranty, implied or otherwise,
regarding these products' performance or reliability.
Modification Type: | Major | Last Reviewed: | 11/4/2003 |
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Keywords: | KB124034 |
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