16All about graphics
3D Interfaces
Software interfaces, including 3D interfaces, are known as APIs (Application Program Interface). The question is what are these interfaces used for, and how do they work.
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, as is shown by the table below. The decisive ques- tions for the user concern extensibility, flexibility and possible portability to existing applications.
Function | Direct 3D | OpenGL |
Alpha blending | K | K |
Texture mapping | K | K |
MIP mapping | K | K |
Video motion mapping | K | k |
Fogging | K | K |
K | K | |
Flat shading | K | K |
Gouraud shading | K | K |
Phong shading | k | k |
Stencil buffer | k | K |
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-
