ELSA ERAZOR X, Руководство пользователя

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All about graphics
ELSA ERAZOR X and ERAZOR X²
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In simple terms: They make developers' work easier. The methods by which the various
interfaces function, are comparable: In the past it was necessary to address the various
hardware components directly in programming if you wanted to exploit their capabilities
to the full. The APIs are a kind of translator operating between the hardware and the
software.
The specification of standard definitions was the precondition for the proper function of
these translation routines. These definitions are implemented by the hardware manufac-
turers during development and optimized for the hardware concerned. Developers can
implement complex procedures relatively easily by using these definitions. They can use
a uniform command set when programming and do not need to know the characteristics
specific to the hardware.
What APIs are available?
There are a good dozen more or less commonly found 3D APIs. However, in recent years,
two formats have established themselves as the favorites: Direct 3D and OpenGL. ELSA
graphics boards support these commonly found 3D interfaces. The functional differences
between the interfaces are slight. The decisive questions for the user concern extensi-
bility, flexibility and possible portability to existing applications.
Direct 3D
As a development of Mode X and DirectDraw under Windows 3.1x, Direct 3D is a branch
of the DirectX multimedia family which was developed directly for Windows 95 to accel-
erate the slow 3D display characteristics of the operating system. Direct 3D is based on
Microsoft's Common Object Model (COM), which is also used as the foundation to OLE
technology (Object Linking and Embedding). Direct 3D cooperates with Direct Draw in
two-dimensional display. A typical situation would be, for instance, rendering a 3D
object while Direct Draw is placing a two-dimensional background bitmap.
Immediate mode and retained mode
As can be assumed from the two terms, immediate mode is a programming mode that is
close to the hardware. Retained mode, on the other hand, is a programming mode that
is largely predefined through an API interface. What does this mean in detail? Looking
at the two systems hierarchically, the immediate mode is also known as the low-level
mode. The programming interface level is close to the hardware level and permits the
programmer direct access to special functions in the hardware component concerned.
The retained mode (high-level mode) makes it possible, for example, to load a defined 3D
object with textures into a Windows application. Here it can be manipulated and moved
using simple API commands. Translation takes place in real time, without the need to
know the technical structure of the object.
For further information see the Internet WWW site http://www.microsoft.com