DirectX

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DirectX
Developer: Microsoft
Latest release: 10.0 / November 30, 2006
OS: Microsoft Windows
Use: Application framework
License: EULA
Website: DirectX Homepage

DirectX is a collection of APIs for handling tasks related to multimedia, especially game programming, on Microsoft platforms. It is widely used in the development of computer games for Microsoft Windows, the Xbox and Xbox 360.

DirectX has also become more widely used among other software production industries. Most notably, Direct3D is becoming more popular among the engineering sector because of its ability to quickly render high-quality 3D graphics using the latest 3D graphics hardware.

Both the DirectX runtime and software development kit are available free of charge. The DirectX runtime was originally redistributed by computer game developers along with their games, but later it was included in Windows. Game developers still often include an updated version of DirectX that prompts installation automatically after the game installation to ensure proper program functionality.

The latest release versions of DirectX are the December 2006 version of DirectX 9.0c, which is available for use on Windows XP and Windows Server 2003, and DirectX 10, which is included with Windows Vista, but is not available for other versions of Microsoft Windows.

Contents

[edit] DirectX APIs

The various components of DirectX are in the form of COM-compliant objects.

The components comprising DirectX are

For Windows Vista and DirectX 10, DirectInput will be deprecated in favor of XInput, from the Xbox team. Likewise, DirectSound will also be deprecated in favor of XACT. As of DirectX 9.0c, however, neither XInput nor XACT have all of the capabilities of DirectInput or DirectSound, and according to MS documentation on XInput, XInput is specifically designed for the Xbox 360 controllers. DirectPlay is deprecated in favor of Xbox Live whereas DirectShow will be deprecated in favor of Media Foundation, a different set of APIs debuting with Windows Vista to handle audio and video playback. DirectMusic will probably remain the only component intact.

[edit] History

In 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.

DirectX was built upon the concepts of a development system known as "Exodus" developed by Kinesoft Development under the direction of the their Founder, Peter Sills and their Director of Technology, Andrew Glaister. Exodus was first shown to Eric Engstrom early in 1994, thus sparking the concept that games could indeed be developed directly for Microsoft's forthcoming operating system, Windows 95. In fact, the first commercial game to ship using Exodus, was Pitfall for Windows 95 (from Activision). It was this title which Bill Gates showed off at that year's COMDEX tradeshow - announcing that Windows 95 would be a top-notch gaming platform. Microsoft worked closely with Kinesoft during that year to develop DirectX 1.0 Earthworm Jim (Activision) and Gex (Microsoft) were also shipped shortly after the release of Windows 95, both using the Exodus engine, which then evolved into DirectX.

Andrew Glaister later went on to be the Development Manager of the Microsoft Game Studios in Redmond, Washington.

The first version of DirectX released was shipped September of 1995 as the Windows Games SDK. It was the Win32 replacement for the poorly designed APIs for the Win16 operating system (DCI and WinG). 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 many computer games because OpenGL does not include all of DirectX's functionality (such as sound or joystick support).

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 console. 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. (J. Allard, PC Pro Interview, April 2004)

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.

[edit] Release history

DirectX version Logo Version number Operating system Date released
DirectX 1.0
4.02.0095   September 30, 1995
DirectX 2.0 / 2.0a   4.03.00.1096 Windows 95 OSR2 and NT 4.0 June 5, 1996
DirectX 3.0 / 3.0a   4.04.0068 / 70 Windows NT 4.0 SP3
last supported version of DirectX for Windows NT 4.0		 September 15, 1996
DirectX 4.0   Never launched  
DirectX 5.0   4.05.00.0155 Available as a beta for Windows NT 5.0 that would install on Windows NT 4.0 July 16, 1997
DirectX 5.1       December 1, 1997
DirectX 5.2   4.05.01.1600 DirectX 5.2 release for Windows 95 May 5, 1998
DirectX 5.2   4.05.01.1998 Windows 98 May 5, 1998
DirectX 6.0   4.06.00.0318 Dreamcast August 7, 1998
DirectX 6.1   4.06.02.0436 Windows 98 SE
last version of DirectX Media for Windows NT 4.0		 February 3, 1999
DirectX 7.0
4.07.00.0700 Windows 2000 September 22, 1999
DirectX 7.0a   4.07.00.0716   1999
DirectX 7.1   4.07.01.3000 Windows ME September 16, 1999
DirectX 8.0
4.08.00.???? (RC0)   September 30, 2000
DirectX 8.0 4.08.00.0400 (RC14) Xbox
 		 November 3, 2000
DirectX 8.0a 4.08.00.0400 (RC14) + installer fixes Last supported version
for Windows 95		 November 7, 2000
DirectX 8.1   4.08.01.0810
4.08.01.0881 (RC7)		 Windows XP November 12, 2001
DirectX 9.0
4.09.0000.0900 Windows Server 2003 December 19, 2002
DirectX 9.0a   4.09.0000.0901   March 26, 2003
DirectX 9.0b   4.09.0000.0902 (RC2)   August 13, 2003
DirectX 9.0c
4.09.0000.0904 (RC0) Windows XP SP2, Windows Server 2003 SP1, and Xbox 360. Last pure 32-bit release. [1] December 13, 2004
DirectX 9.0c   4.09.0000.0904 Compatible with all Windows OS versions that 9.0c (RC0) was compatible with
First version to include D3DX DLLs		 December 9, 2005
DirectX 9.0c - bimonthly updates   4.09.0000.0904 Windows XP
August 2005 was the last build to support Windows 98, Windows 98 SE, Windows ME and Windows 2000.
The December '05, and February '06 updates also add the XML format to some classes. These updates are primarily to D3DX and are only intended for developers and redistributable packages[citation needed], but not the core runtime. They come bimonthly; official recommendation seems to be they should not be downloaded unless a piece of software specifically asks for them[citation needed], despite user reports of increased performance with the newer versions[citation needed].		 Usually released bimonthly from August 2005 until present
DirectX 9.0 EX[1]   Windows Vista Only. Provides DirectX 9 API for Vista. The Inquirer posted an article on October 16, 2006 stating that 9.L would be DirectX 10 for Windows XP, but later stated that it was a mistake.
DirectX 10.0 New version of DirectX only available with Windows Vista. November 30, 2006

Note that the version number as reported by Microsoft's DXDiag tool may 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 data in x.xx.xx.xxxx format. Put another way, when the above table lists a version as '4.09.0000.0904', the registry may have it as '4.09.00.0904'.

[edit] Compatibility

Hardware manufacturers have to write drivers for and test each individual piece of hardware to make them DirectX compatible. Many modern hardware devices only have DirectX compatible drivers (in other words, one must install DirectX before one will be able 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.

Some drivers only support one version of DirectX. Prior to DirectX 10, DirectX was considered backward compatible, which means that newer versions supported the older versions. For example, if one had DirectX 9 installed on one's system and ran a game that was written for DirectX 6, it would still work. The game used what was called the DirectX 6 "interface". Every version of DirectX supported every previous version of DirectX. This is a positive consequence of the COM model used for this API.

This has changed with DirectX 10, which uses a legacy version of DirectX 9.0c (9.0 EX) to support older platforms.

[edit] DirectX 10

See also: Direct3D 10 section at the Direct3D article

Microsoft has several development projects related to DirectX underway.

Microsoft was working on a large update to the Direct3D API. Originally called Windows Graphics Foundation, DirectX 10, and later DirectX Next, but currently referred to as Direct3D 10, it was released as part of Windows Vista. Version 10 represents a departure from the driver model of DirectX Graphics 9.0, with the addition of a scheduler and memory virtualization system. Direct3D 10 will forego the current DirectX practice of using "capability bits" to indicate which features are active on the current hardware. Instead, Direct3D 10 defines a minimum standard of hardware capabilities which must be supported for a display system to be "Direct3D 10 compatible". According to Microsoft, Direct3D 10 will be able to display graphics up to 8 times faster than DirectX Graphics 9.0c. In addition, Direct3D 10 incorporates Microsoft Shader Model 4.0.

Microsoft developed XNA, a framework designed to assist development of games by making it easier to integrate DirectX, High Level Shader Language (HLSL) and other tools in one package.

Although somewhat in its infancy, during 2002 Microsoft released a version of DirectX compatible with the Microsoft .NET Framework, thus allowing programmers to take advantage of .NET features (such as the use of the C# and Visual Basic programming languages) simultaneously with DirectX development. This API is known as "Managed DirectX" and performance is claimed to be 98% of that of native DirectX software.

In December 2005, February 2006, April 2006 and August 2006 Microsoft released a version of 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, 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, which this 2.0 version will be merged into and which will allow for the execution of managed code on the Xbox 360. The XNA Game Studio Express RTM was made available on Dec. 11, 2006, as a free download on Windows XP SP2.

Microsoft also made the requirements for GPU manufacturers to claim to be DirectX 10 compatible much stricter, with only three features optional. [2]. The intention of this is so that game developers will know all the features that the graphics cards have, and so they will be able to make games more effectively, by utilizing all the features of DirectX without worrying about making their games to be able to function without certain features.

DirectX 10 is available exclusively to Vista, which means that computers that aren't running Vista will not be able to run later applications which require DirectX 10; contrary to rumours surrounding the issue, DirectX 10 will not be released to the Xbox 360 via a software patch, this is due to incompatibilities of the graphics hardware[2]. Wine developers have plans to port their upcoming DirectX 10 implementation to older Windows versions.[3][4]

[edit] Alternatives

There are alternatives to this framework, some more complete than others. An example of a cross platform alternative that provides some of the functionality is the combination of OpenGL and OpenAL.

[edit] See also

[edit] References

  1. ^ http://letskilldave.com/archive/2006/10/17/DirectX-10-for-Windows-XP_3F00_--Repeat-after-me_3A00_-No.-No.-No_2E00_.aspx Direct X 9.0 L is now DirectX 9.0 EX
  2. ^ http://www.extremetech.com/article2/0,1697,2000442,00.asp

[edit] External links

[edit] Programmer resources

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