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DirectX
 

DirectX is a collection of APIs for easily handling tasks related to game programming on the Microsoft Windows operating system. It is most widely used in the development of computer games for Microsoft Windows. The DirectX SDK is available free from Microsoft. 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. DirectX 9.0c is the latest release version of DirectX. Direct3D 10 Beta is available as of Windows Vista build 5238. The latest versions of DirectX are still usually included with PC games because the API is often updated.

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, it is rumored that DirectInput will be replaced with XInput, from the Xbox team. Likewise, DirectSound will be replaced with 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.

History

Originally targeted at the game development industry, DirectX has 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.

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.

The first release version of DirectX was shipped September of 1995 as the Windows Games SDK. It was the Win32 replacement for poorly designed, ill-conceived 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 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 *.

Release history

DirectX version Logo Version number Operating system Date released
4.02.0095 September 30, 1995
DirectX 2.0 / 2.0a 4.03.00.1096Windows 95 OSR2 and NT 4.0June 5, 1996
DirectX 3.0 / 3.0a 4.04.0068 / 69Windows 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 (RC55)Available as a beta for Windows NT 5.0 that would install on Windows NT 4.0July 16, 1997
DirectX 5.0 4.05.01.1721 / 1998Windows 98???, 1998
DirectX 6.0 4.06.00.0318 (RC3)Windows 98 SE
last version of DirectX Media for Windows NT 4.0		August 7, 1998
DirectX 6.1 4.06.02.0436 (RC0) February 3, 1999
4.07.00.0700 (RC1)Windows 2000September 22, 1999
DirectX 7.0a 4.07.00.0716 (RC1) ???, 1999
DirectX 7.1 4.07.00.????Windows MESeptember 16, 1999
4.08.00.???? (RC0) September 30, 2000
DirectX 8.04.08.00.0400 (RC14)Xbox
 		November 3, 2000
DirectX 8.0a4.08.00.0400 (RC14) + installer fixesLast supported version
for Windows 95		November 7, 2000
DirectX 8.1 4.08.01.0810
4.08.01.0881 (RC7)		Windows XPNovember 12, 2001
4.09.0000.0900Windows Server 2003December 24, 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 SP2August 9, 2004
DirectX 9.0c 4.09.0000.0904Compatible with all Windows OS versions that 9.0c (RC0) was compatible with
First version to include D3DX DLL's		December 9, 2005
DirectX 9.0c - August, December, February, April 4.09.0000.0904Windows XP
Compatible with all Windows OS versions that 9.0c (RC0) was compatible with
The updates offered Major Security Fixes, and speed improvements.
The December, and February updates also add the XML format to some classes. These updates are primarily to D3DX and only affected developers and redistributable packages, but not the core runtime. They come bimonthly and should not be downloaded unless a piece of software specifically asks for them.
(?)New version of Direct3D only for Windows Vista 

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, you must install DirectX before you 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. But DirectX is backward compatible, which means that newer versions support the older versions. For example, if one has DirectX 9 installed on one's system and runs a game that was written for DirectX 6, it should still work. The game will use what is called the DirectX 6 "interface." Every version of DirectX must support every previous version of DirectX. This is a positive consequence of the COM model used for this API.

The future of DirectX

Microsoft has several development projects related to DirectX underway.

Microsoft is currently 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 will appear as part of Windows Vista. Version 10 will represent 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 will define 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 will incorporate Microsoft Shader Model 4.0.

Microsoft is also developing XNA, which is 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, and April 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. There is no announced release date for the XNA framework.

DirectX 10 is available exclusively to Vista, which means that machines that aren't running Vista technically will not be able to run later games which require DirectX 10. This pushes the debate of whether people are forced to upgrade, or go for alternative solutions.

See also

External links

Programmer resources

Application programming interfaces | Microsoft APIs | Microsoft Windows

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This article is licensed under the GNU Free Documentation License. It uses material from the "DirectX".

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