DIRECTX

'Microsoft DirectX' is a collection of application programming interfaces for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with Direct, such as Direct3D, DirectDraw, DirectMusic, DirectPlay, DirectSound, and so forth. DirectX, then, was the generic term for all of these Direct-something APIs, and that term became the name of the collection. Over the intervening years, some of these APIs have been deprecated and replaced, so that this naming convention is no longer absolute. In fact, the X has caught on to the point that it has replaced Direct as the common part in the names of new DirectX technologies, including XAct, XInput, and so forth.
Direct3D (the 3D graphics API within DirectX) is widely used in the development of computer games for Microsoft Windows, Microsoft Xbox, and Microsoft Xbox 360. Direct3D is also used by other software applications for visualization and graphics tasks, most notably among the engineering sector for CAD/CAM, because of its ability to quickly render high-quality 3D graphics using DirectX-compatible graphics hardware. As Direct3D is the most widely recognized API in DirectX, it is not uncommon to see the name DirectX used in place of Direct3D.
The interfaces that comprise DirectX include components for use by a running application (runtime components) as well as components for use by software developers at design time (the software development kit). The runtimes were originally redistributed by computer game developers along with their games, but are now included as built-in parts of Microsoft Windows. The SDK is available as a free download. While the runtimes are proprietary, closed-source software, source code is provided for most of the SDK samples.
The latest versions of Direct3D, namely, Direct3D 10 and Direct3D 9Ex, are exclusive to Windows Vista. This is because there were extensive changes in the Windows graphics architecture, and in particular the introduction of the Windows Display Driver Model. This redesign of the graphics infrastructure for Windows Vista supports virtualizing graphics hardware to multiple applications and services such as the Desktop Window Manager, in contrast to the exclusive access afforded to DirectX applications on Windows XP. Both Direct3D 9Ex and Direct3D 10 rely on the WDDM infrastructure and WDDM drivers.

Contents

Components

DirectX 10

DirectX 10.1

History

Release history

History of DirectX logo

Compatibility

.NET Framework

Alternatives

See also

DirectX alternatives

References

External links

Components

DirectX functionality is provided in the form of Component Object Model interfaces, as well as a set of managed code interfaces.
The components comprising DirectX are

★ 'DirectX Graphics', comprising two APIs:

★
★ DirectDraw: for drawing 2D Graphics (raster graphics) (now mostly deprecated, although still in use by many)

★
★ Direct3D (D3D): for drawing 3D graphics

★ DirectInput: for interfacing with keyboards, mice, joysticks, or other game controllers (Not updated since 8 except for XInput, which is specifically for Xbox360 controllers. For keyboards and mice, WM INPUT is recommended instead.)

★ DirectPlay: for networked communication of games (Along with DirectInput, was last updated in version 8. Now deprecated.)

★ DirectSound: for the playback and recording of waveform sound

★
★ DirectSound3D (DS3D): for the playback of 3D sounds.

★ DirectMusic: for playback of soundtracks authored in DirectMusic Producer

★ DirectX Media: comprising DirectAnimation for 2D web animation, DirectShow for multimedia playback and streaming media, DirectX Transform for web interactivity and Direct3D Retained Mode for higher level 3D graphics. DirectShow additionally contains DirectX plugins for audio signal processing and DirectX Video Acceleration for accelerated video playback.

★ DirectX Media Objects: support for streaming objects such as encoders, decoder and effects

★ DirectSetup: for the installation of DirectX components, not really an API

DirectX 10

:''For the list of games that (will) support DirectX 10, see List of games with DirectX 10 support.''
Windows Vista ships with DirectX 10 and is the only version of Windows for which it is offered, and it has a large number of changes: DirectInput will be deprecated in favor of XInput, from the Xbox team. Likewise, DirectSound will also be deprecated in favor of XACT. DirectX 10 has also dropped support for hardware accelerated audio, opting instead to render sound in software on the CPU.
In order to achieve backwards compatibility with previous versions of Direct3D, DirectX 10 contains three versions of Direct3D:^[1]

★ 'Direct3D 9': emulates Direct3D 9 behavior as it was on Windows XP. Details and advantages of Vista's Windows Display Driver Model are hidden from the application if WDDM drivers are installed. This is the only API available if there are only XP graphic drivers (XPDM) installed, after an upgrade to Vista for example.

★ 'Direct3D 9Ex' (known internally during Windows Vista development as 9.0L or 9.L, the L referring to Longhorn, the codename for Windows Vista): allows full access to the new capabilities of WDDM (if WDDM drivers are installed) while maintaining compatibility for existing Direct3D applications. The Windows Aero user interface relies on D3D 9Ex.

★ 'Direct3D 10': Designed around the new driver model in Windows Vista and featuring a number of improvements to rendering capabilities and flexibility, including Shader Model 4.

DirectX 10.1

DirectX 10.1 is an incremental update to DirectX 10.0 which will be shipped with, and require, Windows Vista Service Pack 1 in January 2008.^[2] DirectX 10.1 will be backwards compatible with DirectX 10.0 hardware, but the new features will not be available until 10.1 compliant hardware is released. The release mainly sets a few more image quality standards for graphics vendors, while giving developers more control over image quality.^[3]
Features scheduled for DirectX 10.1 include:

★ Mandatory 32-bit floating point filtering

★ Mandatory 4x anti-aliasing

★ Shader model 4.1

History

In late 1994 Microsoft was just on the verge of releasing its next operating system, Windows 95. The main factor that would determine the value consumers would place on their new operating system very much rested on what programs would be able to run on it. Three Microsoft employees — Craig Eisler, Alex St. John, and Eric Engstrom — were concerned, because programmers tended to see Microsoft's previous operating system, DOS, as a better platform for game programming, meaning few games would be developed for Windows 95 and the operating system would not be as much of a success.

DOS allowed direct access to video cards, keyboards and mice, sound devices, and all other parts of the system, while Windows 95, with its protected memory model, restricted access to all of these, working on a much more standardized model. Microsoft needed a way that would let programmers get what they wanted, and they needed it quickly; the operating system was only months away from being released. Eisler, St. John, and Engstrom conspired together to fix this problem, with a solution that they eventually named DirectX.

The first version of DirectX released was shipped September of 1995 as the Windows Games SDK. It was the Win32 replacement for the DCI and WinG APIs for Windows 3.1. A development team at ATI brought fundamental game graphics technology to the attention of Microsoft. The development of DirectX was led by the team of Eisler (development lead), St. John, and Engstrom (program manager). Simply put, it allowed all versions of Microsoft Windows, starting with Windows 95, to incorporate high-performance multimedia. Eisler wrote about the frenzy to build DirectX 1 through 5 in his blog.

Prior to DirectX's existence, Microsoft had already included OpenGL on their Windows NT platform. At the time, OpenGL required "high-end" hardware and was limited to engineering and CAD uses. Direct3D (introduced by Eisler, Engstrom, and St. John as an alternative to SGI's OpenGL) was intended to be a lightweight partner to the back then slower OpenGL for game use. As the power of graphics cards and the computers running them grew, OpenGL became the de-facto standard and a mainstream product. At that point a "battle" began between supporters of the cross-platform OpenGL and the Windows-only Direct3D, which many argued was another example of Microsoft's embrace, extend and extinguish business tactic (see Fahrenheit or Direct3D vs. OpenGL). Nevertheless, the other APIs of DirectX are often combined with OpenGL in computer games because OpenGL does not include all of DirectX's functionality (such as sound or joystick support). However, the combination of OpenGL and OpenAL for this purpose is becoming increasingly popular.

In a console-specific version, DirectX was used as a basis for Microsoft's Xbox and Xbox 360 console API. The API was developed jointly between Microsoft and NVIDIA, who developed the custom graphics hardware used by the original Xbox. The Xbox API is similar to DirectX version 8.1, but is non-updateable like other console technologies. The Xbox was code named DirectXbox, but this was shortened to Xbox for its commercial name.^[4]

In 2002 Microsoft released DirectX 9 with support for the use of much longer shader programs than before with pixel and vertex shader version 2.0. Microsoft has continued to update the DirectX suite since then, introducing shader model 3.0 in DirectX 9.0c, released in August 2004.

As of April 2005, DirectShow was removed from DirectX and moved to the Microsoft Platform SDK instead. DirectX is, however, still required to build the DirectShow samples^[5].

Release history

DirectX version	Version number	Operating system	Date released
DirectX 1.0	4.02.0095		September 30 1995
DirectX 2.0	?	''Was shipped only with a few 3rd party applications''	1996
DirectX 2.0a	4.03.00.1096	Windows 95 OSR2 and NT 4.0	June 5 1996
DirectX 3.0	4.04.00.0068		September 15 1996
	4.04.00.0069	''Later package of DirectX 3.0 included Direct3D 4.04.00.0069''	1996
DirectX 3.0a	4.04.00.0070	Windows NT 4.0 SP3 (and above) ''last supported version of DirectX for Windows NT 4.0''	December 1996
DirectX 3.0b	4.04.00.0070	''This was a very minor update to 3.0a that fixed a cosmetic problem with the Japanese version of Windows 95''	December 1996
DirectX 4.0	Never launched
DirectX 5.0	4.05.00.0155 (RC55)	''Available as a beta for Windows NT 5.0 that would install on Windows NT 4.0''	July 16 1997
DirectX 5.2	4.05.01.1600 (RC00)	''DirectX 5.2 release for Windows 95''	May 5 1998
	4.05.01.1998 (RC0)	Windows 98 exclusive	June 25 1998
DirectX 6.0	4.06.00.0318 (RC3)	Windows CE for the Dreamcast	August 7 1998
DirectX 6.1	4.06.02.0436 (RC0)		February 3 1999
DirectX 6.1a	4.06.03.0518 (RC0)	Windows 98 SE exclusive	May 5 1999
DirectX 7.0	4.07.00.0700 (RC1)		September 221999
	4.07.00.0700	Windows 2000	February 17 2000
DirectX 7.0a	4.07.00.0716 (RC0)		March 8 2000
	4.07.00.0716 (RC1)		2000
DirectX 7.1	4.07.01.3000 (RC1)	Windows Me exclusive	September 14 2000
DirectX 8.0	4.08.00.0400 (RC10)		November 12 2000
DirectX 8.0a	4.08.00.0400 (RC14)	''Last supported version for Windows 95''	February 5 2001
DirectX 8.1	4.08.01.0810	Windows XP, Windows Server 2003 and Xbox exclusive	October 25 2001
	4.08.01.0881 (RC7)	''This version for the down level operating systems (Windows 98, Windows Me and Windows 2000)''	November 8 2001
DirectX 8.1a	4.08.01.0901 (RC?)	''This release includes an update to Direct3D (D3d8.dll)''	2002
DirectX 8.1b	4.08.01.0901 (RC7)	''This update includes a fix to DirectShow on Windows 2000 (Quartz.dll)''	June 25 2002
DirectX 8.2	4.08.02.0134 (RC0)	''Same as the DirectX 8.1b but includes DirectPlay 8.2''	2002
DirectX 9.0	4.09.00.0900 (RC4)		December 19 2002
DirectX 9.0a	4.09.00.0901 (RC6)		March 26 2003
DirectX 9.0b	4.09.00.0902 (RC2)		August 13 2003
DirectX 9.0c	4.09.00.0903	Service Pack 2 for Windows XP exclusive
	4.09.00.0904 (RC0)		August 4 2004
	4.09.00.0904	Windows XP SP2, Windows Server 2003 SP1, Windows Server 2003 R2 and Xbox 360	August 6 2004
DirectX 9.0c - bimonthly updates	4.09.00.0904 (RC0)	''The December '06 is last supported version for Windows 98 and Windows Me. The December '05, and February '06 updates also add the XML format to some classes.''	Released bimonthly from October 2004 to August 2007, and quarterly thereafter; Latest version: August, 2007
DirectX 10.0	6.0.6000.16386	Windows Vista exclusive	November 30 2006

Notes:
# DirectX 4 was never released. Raymond Chen explained in his book, ''The Old New Thing'', that after DirectX 3 was released, Microsoft began developing versions 4 and 5 at the same time. Version 4 was to be a shorter-term release with small features, whereas version 5 would be a more substantial release. The lack of interest from game developers in the features slated for DirectX 4 resulted in its being shelved, and the corpus of documents that already distinguished the two new versions resulted in Microsoft choosing to not re-use version 4 to describe features intended for version 5.^[6]
# The version number as reported by Microsoft's DxDiag tool (version 4.09.0000.0900 and higher) use the x.xx.xxxx.xxxx format for version numbers. However, Microsoft's site at http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/directx9_c_Dec_2004/directx/directxsdk/dxandxp.asp claims that the registry always has in the x.xx.xx.xxxx format. Put another way, when the above table lists a version as '4.09.00.0904' the registry may have it as '4.09.0000.0904'.

History of DirectX logo

The X originally resembled a cross between a radiation warning symbol and a propeller blade. Controversially, the original name for the DirectX project was the "Manhattan Project", a reference to the US nuclear weapons initiative and its ultimate outcome — the nuclear bombing of Japan. Conspiracy theorists have argued that this connotation is intentional, and that DirectX and its sister project, the Xbox (which shares a similar logo), are meant to displace Japanese videogame makers from their dominance of the industry. However, this meaning is publicly denied by Microsoft, who instead claims that it is merely artistic design.^[7] Furthermore, no sinister explanation is necessary; the simple (but less sensational) explanation is that the X in DirectX was chosen for its geek chic factor, and the X logo was chosen to accentuate this. Since both the name of the API and the logo were chosen years before Microsoft even considered entering the game console market — much less designed the Xbox — there is no basis for a claim that the X logo anticipated competition with Japanese console makers.

DirectX 1.0–6.0

DirectX 7.0

DirectX 8.0

DirectX 9.0

DirectX 10.0

Compatibility

APIs such as Direct3D and DirectSound need to interact with hardware, and they do this through a device driver. Hardware manufacturers have to write these drivers for a particular DirectX version's device driver interface (or DDI), and test each individual piece of hardware to make them DirectX compatible. Some hardware devices only have DirectX compatible drivers (in other words, one must install DirectX in order to use that hardware). Early versions of DirectX included an up-to-date library of all of the DirectX compatible drivers currently available. This practice was stopped however, in favor of the web-based Windows Update driver-update system, which allowed users to download only the drivers relevant to their hardware, rather than the entire library.
Prior to DirectX 10, DirectX was designed to be ''backward compatible'' with older drivers, meaning that newer versions of the APIs were designed to interoperate with older drivers written against a previous version's DDI. For example, a game designed for and running on Direct3D 9 with a graphics adapter driver designed for Direct3D 6 would still work, albeit possibly with gracefully degraded functionality. However, as of Windows Vista, due to the significantly updated DDI for Windows Display Driver Model drivers, Direct3D 10 cannot run on older hardware drivers.
Various releases of Windows have included and supported various versions of DirectX, allowing newer versions of the operating system to continue running applications designed for earlier versions of DirectX until those versions can be gradually phased out in favor of newer APIs, drivers, and hardware.

.NET Framework

During 2002 Microsoft released a version of DirectX compatible with the Microsoft .NET Framework, thus allowing programmers to take advantage of .NET features (the use of the C# programming language) simultaneously with DirectX development. This API is known as "Managed DirectX" (or MDX for short) and performance is claimed to be 98% of that of native DirectX software. The design ideas behind Managed DirectX can be seen in the newer framework XNA which also implements Managed DirectX along with other technologies aimed at making game development easier.
In December 2005, February 2006, April 2006, and August 2006, Microsoft released successive updates to DirectX that is designed for the .NET 2.0 framework. In older versions, DirectX was split apart into different modules; this has changed with the .NET 2.0 version, as it is now a single file and is much easier to use. However, the .NET 2.0 version of DirectX is not a finalized version; it is still a beta.
During the GDC 2006 Microsoft presented the XNA Framework, a framework built on Managed DirectX that is intended to assist development of games by making it easier to integrate DirectX, High Level Shader Language (HLSL) and other tools in one package. It also supports the execution of managed code on the Xbox 360. The XNA Game Studio Express RTM was made available on December 11 2006, as a free download for Windows XP.

Alternatives

There are alternatives to the DirectX family of APIs, some more complete than others. While there is no unified solution that will do everything DirectX does, with a combination of libraries — SDL, OpenMAX, OpenML, OpenGL, OpenAL, FMOD, etc. — one can implement a comparable but cross-platform and frequently free/open source solution.
There are also alternative implementations that aim to provide the same API, such as the one in Wine.
Additionally, because Direct3D 10 is not available on Windows XP, Cody Brocious has started the "Alky Project," which he intends to allow Direct3D 10 games to run on a computer with Windows XP installed. In concept, Alky compatibility libraries for Microsoft Direct3D 10 enabled games would allow them to run on platforms other than Windows Vista and increase hardware compatibility even on Vista, by compiling geometry shaders down to native machine code for execution on the CPU when the GPU is not capable of running it. This would reduce the need for an upgraded graphics card and operating system in order to use Direct3D 10 applications.

See also

★ Graphics Device Interface (GDI)

★ Graphics pipeline

★ DxDiag

★ DirectX plugin

★ ActiveX

DirectX alternatives

★ General Graphics Interface (GGI)

★ Simple DirectMedia Layer

★ OpenMAX

★ OpenML

★ OpenGL

★ OpenAL

★ Cedega

References

1. Graphics APIs in Windows Vista Chuck Walbourn
2. Microsoft Unleashes First Service Pack for Vista
3. Microsoft Presents DirectX 10.1 Details at SIGGRAPH
4. J. Allard, PC Pro Interview, April 2004
5. [1]
6. The Old New Thing, , Raymond, Chen, Pearson Education, 2006, ISBN 0-321-44030-7
7. Alex St John Interview David Craddock

External links

★ Microsoft's DirectX site

★