DirectX

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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. DirectX 9.0c is the latest release version of DirectX. DirectX 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.

Contents

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DirectX APIs

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

The components comprising DirectX are :

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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). 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 yet in itself include all of DirectX's functionality (such as sound or joystick support). Previous attempts to address this have failed but a new draft of OpenGL aims to provide all of DirectX's functionality and device 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 supposed to be named DirectXbox, but was shortened to Xbox.

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 [1].

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Release history

DirectX version Logo Version number Operating system Date released
DirectX 1.0Image:Directx1.gif4.02.0095 September 30th, 1995
DirectX 2.0 / 2.0a 4.03.00.1096Windows 95 OSR2 and NT 4.0June 5th, 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 15th, 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 16th, 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) ???, 1999
DirectX 7.0Image:Dx7logo.gif4.07.00.0700 (RC1)Windows 2000 and MESeptember 22, 1999
DirectX 7.0a 4.07.00.0716 (RC1) ???, 1999
DirectX 8.0Image:Dx8logo.gif4.08.00.0400 (RC14)Xbox
Last supported version
for Windows 95		November 8, 2000
DirectX 8.1 4.08.01.0810
4.08.01.0881 (RC7)		Windows XPNovember 12, 2001
DirectX 9.0Image:Directx9.jpg4.09.0000.0900Windows 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.
D3D 10 (coming with Windows Vista) (?)New version of Direct3D only for Windows Vista 
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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.

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The future of DirectX

Template:Future software 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 more quickly 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, 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 the December 2005 and February 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, it should be noted that .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, of which this 2.0 version will be a major part and which will allow for the execution of managed code on the XBox360.

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See also

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External links

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Programmer resources

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