Technical information

Reviewer’s Guide Microsoft Windows NT Workstation 3.51 11
Features of OpenGL
Feature Description
Texture mapping The process of applying an image to a graphics primitive. This technique is used to
generate realistic images. For example, a table surface can be drawn as a rectangle
and a wood-grain texture can be applied to it.
Double buffering Support for contexts with front and back color buffers. Smooth animation can be
achieved by drawing into the back buffer, which isn’t actively displayed and then
swapping buffers with the front buffer when ready to display.
Z- buffering The ability to buffer “depth.” This is mainly used for hidden surface removal.
Gourad shading The ability to apply smooth shading to a geometric primitive. This is used to
compute subtle differences in color across a given surface.
Lighting, materials The ability to compute the color of any point accurately, given material properties
for the surface and a lighting model.
Transforms The ability to change the perspective of an object in 3-D coordinate space.
Anti-aliasing A technique used to reduce jagged edges in lines drawn on a computer display.
Alpha blending The ability to specify a fourth color component in addition to R-G-B. Alpha is used
to specify opacity, from completely transparent to opaque.
The Windows NT Workstation implementation of OpenGL release 1.0 includes all the standard APIs. Furthermore,
Microsoft has defined additional APIs known as “wgl,” which glue the OpenGL implementation to the Windows NT
Workstation windowing system. All of these interfaces are documented in the Windows NT Workstation software
Development Kit (SDK). OpenGL will work on any hardware that is compatible with Windows NT Workstation.
Minimally, it will work on a VGA in 640x480 with 16 colors. However, it is desirable to run OpenGL applications
on higher resolution Windows NT Workstation video monitors that are capable of displaying a larger color palette.
In this mode, all of the OpenGL operations are executed in software.
Some users will need increased performance for CAD design or animation work which commonly requires some
form of hardware acceleration. Microsoft is defining a set of Rendering/CAD Device Driver Interface (DDI)
Extensions to address this need. Hardware acceleration will enable video adapter manufacturers to accelerate 3-D
graphics for their cards. Windows NT Workstation allows many of the primitives in the Rendering / CAD DDI
Extensions to be sent directly to the hardware in order to accelerate OpenGL performance on capable hardware. This
interface is being provided in the new version of the Windows NT Workstation Device Driver Kit (DDK). In this
hybrid scenario, many key OpenGL operations can be executed in hardware, with the rest executed in software,
resulting in improved performance over the software-only mode.
Finally, the Windows NT Workstation implementation of OpenGL also enables existing workstation class 3-D
graphics hardware, such as SGI’s, which is capable of the highest performance, and can meet the most demanding
user needs. In this scenario, graphics hardware contains a majority of 3-D OpenGL functionality. Little of the
graphics code executes in software, resulting in the best OpenGL 3-D graphics performance.
Enhanced Connectivity Features
Windows NT 3.1 was the first advanced operating system to offer transport-independent networking with its ability
to install and configure new transports easily through the Control Panel networks applet. Windows NT Workstation
has matured considerably in its ability to connect to a wide range of systems. Microsoft has devoted considerable
effort to providing native connectivity services within the core product package.
Microsoft has worked with many third parties providing networking products to ensure that the range of connectivity
services provided for Windows NT Workstation is as broad as possible. The following sections address these
connectivity improvements.