DirectX 6 and Onwards
Right - let's get some stuff clearer up right away. Windows 98 comes with DirectX 5.x not DirectX 6 like NT5 will. DirectX 6 should be a major upgrade for a lot of users, it adds a whole host of new features for 3D cards, which we will talk about in the near future.
DirectX 6 Features
DirectX 6.0 APIs reduce development time by giving developers of games and other interactive content access to specialised hardware features without having to write hardware-specific code. Consisting of the DirectX foundation layer, for low-level hardware acceleration services, and the DirectX media layer, for high-level media integration services, DirectX 6.0 is a next-generation unified API set with advanced multimedia functionality from the chip level to high-level run-time engines on the Windows operating system.
The DirectX foundation layer provides low-level services through the Direct3D(R) Immediate Mode, DirectDraw(R), DirectSound(R), DirectMusic(TM) and DirectInput(R) APIs. DirectX 6.0 features new foundation layer capabilities, with a focus on these Direct3D enhancements:
* Multiple textures. The ability to
render multiple textures
* New rasterizers. Complete software
rasterizers for nonhardware
* Geometry pipeline features. More geometry layouts accepted, as well as strided vertex formats; includes bounding sphere visibility acceleration checks
* DrawPrimitives2 DDI. More efficient connection to device drivers
* Texture memory manager. Texture memory management support
* Flexible vertex format. Ability to specify more texture coordinates and color per vertex when lighting; eliminates the need to specify color data if none exists
* Vertex buffers. Ability to cache geometry in system, video or Accelerated Graphics Port (AGP) memory
* Bump mapping. Support for several techniques for performing per-pixel bump mapping
* Standard fixed-rate texture compression. Format that allows authoring of textures in 6x compressed format, and direct rendering of those textures
* Opaque texture surfaces. Ability to recommend or disallow hardware-specific real-time optimization and compression of textures
* Alpha in texture palettes. Ability to specify an alpha channel in a texture palette -- an alternative to chromakey transparency
* Luminance surfaces. Ability to create and utilize single-channel surface formats (can be used for light and dark maps, bump maps, etc.)
* Stencil planes. Used to control drawing to some areas, simulate shadows and other effects
* W-buffering. Alternative form of z-buffering that is more accurate in some cases
* Range-based fog. Fog calculations improved to correct for planar viewing geometry
* Z-buffer clearing. Ability to clear z-buffer to arbitrary value in one call
In addition, enhancements to DirectDraw include the following:
* Full-screen-only per-channel gamma control. Allows applications to set gamma levels for each primary color channel (red, green, blue) when running in full-screen mode.
* Motion compensation. A portion of the MPEG decoding process that most graphics adapters are now supporting in hardware; this enables software MPEG2 decoders to achieve a 20 to 40 percent frame rate increase.
* Hardware de-interlacing support. The ability to perform high-quality temporal interpolation of video frames to seamlessly match video frame rate with monitor refresh rate
DirectX 6.0 also introduces DirectMusic, a new API that delivers superior, high-quality music to the Windows platform. Features include the following:
* Better MIDI sequencing. DirectMusic provides a high-quality sequencer for rock-steady playback of MIDI streams.
* Support for the downloadable sounds (DLS) standards authored by the MIDI Manufacturers Association. This feature enables developers to take advantage of the latest sound cards equipped with wavetable synthesis, by adding new, customized instruments to the set of instruments delivered by the sound card.
* A high-quality, low-overhead software synthesizer. On systems that do not have wavetable synthesizers, the Microsoft software synthesizer can create high-quality music that is fed through the sound card's digital audio playback system. This software synthesizer imposes little CPU overhead and supports all DirectMusic features, including DLS.
* Interactive music composition. Composers can now add information to their musical scores that instructs DirectMusic on how it should adapt the score based on a player's actions. Music can become more intense, more dramatic or more exciting in real-time, drawing users into the action.
DirectX media provides high-level media integration services through the Direct3D Retained Mode, DirectPlay(R), DirectShow(TM) and DirectAnimation(TM) APIs. DirectX 6.0 updates DirectPlay with the following features:
* Guaranteed messaging. Supports guaranteed message delivery on all networks, including IPX and head-to-head modem, and provides better performance than TCP on the Internet.
* Asynchronous messages. The ability to send messages and receive confirmations later rather than having to wait for a message to complete.
* Firewall support. Fixed port numbers enable configuration of firewalls to allow network gaming.
DirectX 6.0 also updates Direct3D Retained Mode with the following features:
* External visuals. Allow developers to provide their own visuals and use them seamlessly within the Retained Mode hierarchy.
* Extended IDirect3DRM MeshBuilder 3 interface. Provides optimized methods for manipulating meshes and support for triangle strip and fan data.
* High-performance DirectXFile API. Delivers a standard method for reading and writing .X files.
* Clipped visuals. Enable arbitrary plane clipping.