Providing Standards for Hardware Accelerators

The primary goals of the DirectX 2 SDK are to provide portable access to the features in use with MS-DOS® today, to not compromise MS-DOS or game console performance, and to remove the obstacles to hardware innovation on the personal computer platform.

Another important goal is to provide guidelines for hardware companies based on feedback from high-performance application developers and independent hardware vendors (IHVs). Therefore, the DirectX 2 SDK components often provide specifications for hardware accelerator features that do not yet exist. In many cases, these specifications are emulated in the software. In other cases, the capabilities of the hardware must be polled first, and the feature bypassed if it is not supported.

Some of the display hardware features coming out in the near future include:

·Overlays. Overlays will be supported so page flipping will be enabled within a window in a graphic device interface (GDI). Page flipping is the double-buffer scheme used to display frames on the entire screen.

·Sprite engines, used to make overlaying sprites easier.

·Stretching with interpolation. Stretching a smaller frame to fit the entire screen can be an efficient way to conserve display RAM.

·Alpha blending, used to mix colors at the hardware pixel level.

·Three-dimensional (3D) accelerators with perspective-correct textures. This allows textures to be displayed on a 3D surface; for example, hallways in a castle generated by 3D software can be textured with a brick wall bitmap that maintains the correct perspective.

·Z-buffer-aware blits for 3D graphics.

·2 megabytes (MB) of display memory as standard. 3D games, for example, generally need at least this much display RAM.

·A compression standard so you can put more data into display memory. This standard will be used for textures, will include transparency compression, and will be very fast when implemented in software as well as hardware.

Audio hardware features that will be released include:

·3D audio enhancers that provide a spatial placement for different sounds. This will be particularly effective with headphones.

·Onboard memory for audio boards.

·Audio-video combination boards that share onboard memory.

In addition, video playback will see the benefit of hardware accelerators that will be compatible with the DirectX 2 SDK. One of the features that will be supported by future releases of the DirectX 2 SDK is hardware-accelerated decompression of YUV video.