DirectX

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DirectX
Image:DirectX 10 logo.png
Developer: Microsoft
Latest release: 10.0 / November 30, 2006
OS: Microsoft Windows
Use: Application framework
License: EULA
Website: DirectX Homepage

Microsoft DirectX is a collection of APIs for handling tasks related to multimedia, especially game programming, on Microsoft platforms. One portion of it, Direct3D, competes against OpenGL and others against SDL. It is widely used in the development of computer games for Microsoft Windows, Microsoft Xbox and Microsoft Xbox 360.

DirectX is also used among other software production industries, most notably 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, but are proprietary and closed-source software. The DirectX runtime was originally redistributed by computer game developers along with their games, but later it was included in Microsoft 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 version of DirectX, DirectX 10, is exclusive to Microsoft Windows Vista.

Contents

[edit] DirectX APIs

DXDiag running in Windows Vista
DXDiag running in Windows Vista

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

The components comprising DirectX are

[edit] 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 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 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 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 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 Windows CE for the 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 4.09.00.0900 Windows Server 2003 December 19, 2002
DirectX 9.0a 4.09.00.0901   March 26, 2003
DirectX 9.0b 4.09.00.0902 (RC2)   August 13, 2003
DirectX 9.0c 4.09.00.0904 (RC0) Windows XP SP2, Windows Server 2003 SP1, and Xbox 360. Last pure 32-bit release. December 13, 2004
DirectX 9.0c 4.09.00.0904 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 4.09.00.0904 The December '05, and February '06 updates also add the XML format to some classes. Usually released bimonthly from August 2005 until present; Latest version: February 2, 2007
DirectX 10.0 Windows Vista exclusive November 30, 2006

[edit] Compatibility

Hardware manufacturers have to write drivers for 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.

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.

With Windows Vista and the radically changed Direct3D 10, this is no longer possible for handling 3D graphics. DirectX 10 therefore also supplies the Direct3D 9 API so older games and applications can still use graphics hardware..

[edit] 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. 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.[citation needed]

[edit] Direct3D

A major new feature of DirectX 10 is Direct3D 10 (originally called Windows Graphics Foundation). By using the new Windows Display Driver Model, Shader Model 4 and new, more strict requirements for GPU manufacturers to claim Direct3D 10 compatibility,[1] version 10 of Direct3D represents a departure from the practices of previous versions. In order to achieve backwards compatibility with previous versions of Direct3D, DirectX 10 actually contains three versions of Direct3D:[2]

  • Direct3D 9: this API emulates all Direct3D 9 on Windows XP behavior (and its quirks) in order to achieve full compatibility with older applications. All the 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 (previously known as 9.0L): allows full access to the new capabilities of WDDM while maintaining compatibility for existing Direct3D applications by putting it in a separate API. The transparency ("Glass") effects in Windows Aero rely on the D3D 9Ex code path. When 9Ex was still codenamed 9.0L, there were rumors that this would be Direct3D 10 for Windows XP.[3] It was quickly pointed out that this was not the case, mainly due to lack of support for WDDM in Windows XP.[4]
  • Direct3D 10 Currently, the only graphics hardware compatible with Direct3D 10 is the NVIDIA GeForce 8 Series which has thus far limited the advent of Direct3D 10-capable applications. Contrary to rumors surrounding the issue, Direct3D 10 will not be released on the Xbox 360 via a firmware update due to incompatibilities with its graphics hardware.[5]

[edit] Other information

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 still 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" (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 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, 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, 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

[edit] Alternatives

There are alternatives to this framework, some more complete than others. While there is no unified solution that will do everything DirectX does, with a combination of libraries - OpenGL, OpenAL, SDL, openML, 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.

[edit] History of DirectX logo

DirectX 1.0 - 6.0

DirectX 7.0

DirectX 8.0

DirectX 9.0

DirectX 9.0c

DirectX 10.0

[edit] See also

Portal:Microsoft
 Microsoft Portal

[edit] References

  1. ^ http://www.extremetech.com/article2/0,1697,2000442,00.asp
  2. ^ Chuck Walbourn (August 2006). Graphics APIs in Windows Vista. MSDN. Retrieved on 2007-02-26.
  3. ^ Fuad Abazovic (October 16, 2006). DirectX 9.L will be a DirectX 10 for Windows XP, apparently. Retrieved on 2007-02-26.
  4. ^ David Weller (October 17, 2006). DirectX 10 for Windows XP? Repeat after me: No. No. No.. Let's Kill Dave!. Retrieved on 2006-12-31.
  5. ^ Patrick Klepek (August 23, 2006). Xbox 360 Not Upgradable to DirectX 10. 1UP.com. Retrieved on 2006-12-31.

[edit] External links

[edit] Programmer resources


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