DirectInput

In computing, DirectInput is a legacy Microsoft API for collecting input from a computer user, via input devices such as the mouse, keyboard, or a gamepad. It also provides a system for ''action mapping,'' which allows the user to assign specific actions within a game to the buttons and axes of the input devices. Additionally it handles '' haptic feedback'' (input/output) devices. Microsoft introduced a new input library called XInput specifically for the Xbox 360 controller.

DirectInput and XInput provide benefits over normal Win32 input events:

* they enable an application to retrieve data from input devices even when the application is in the background
* they provide full support for any type of input device, as well as for ''haptic feedback''
* through ''action mapping'', applications can retrieve input data without needing to know what kind of device generated that input

While DirectInput forms a part of the DirectX library, it has not been significantly revised since DirectX 8 (2001–2002). Microsoft recommends that new applications make use of the Windows message loop for keyboard and mouse input instead of DirectInput (as indicated in the Meltdown 2005 slideshow), and to use XInput instead of DirectInput for Xbox 360 controllers.

History

DirectX included DirectInput from version 1.0 (1995). It initially offered true support only for joysticks, as the mouse and keyboard modules simply provided wrappers to the standard Win32 API. DirectX version 3.0 (1996) added support for keyboards and mice; it also improved joystick support. DirectX 5.0 (1997) included greatly improved joystick support, including adding haptic feedback, increasing the number of buttons, changing the underlying device-driver model and incorporating a COM-based API. Mouse support also increased the number of buttons seen from four to eight. In DirectX 7.0 (1999- ), DirectInput added a long-promised feature of seeing individual mice much like individual joysticks, but the feature didn't work with the later released Windows XP, even though it works with Windows 98/Me and DirectX 9. DirectX 8.0 (2000), the last version with major changes, included action mapping and broader support for different types of devices.

While Microsoft initially intended that DirectInput would handle all inputs, this didn't work out. Microsoft no longer recommends using DirectInput for keyboards or mice, and has started pushing the newer XInput for Xbox 360 controllers. In Windows Vista, Windows 7 and later Windows versions, the in-built action mapping UI has been removed. DirectInput is not available for Windows Store apps.

XInput

XInput, an API for "next generation" controllers, was introduced in December 2005 alongside the launch of the Xbox 360. This specification provided support for Xbox 360 controllers in Windows XP SP1 and subsequent operating systems, and is described by Microsoft as being easier to program for and requiring less setup than DirectInput. XInput is compatible with DirectX version 9 and later.

Xbox 360 Controller support

An ''Xbox 360 Controller'', with the default Microsoft driver, has the following limitations with DirectInput, compared to XInput:

* the left and right triggers will act as a single axis representing the signed difference between the triggers, not as independent analog axis
* vibration effects will not operate
* querying for headset devices will not operate, XInput 1.4 as part of Windows 8 introduced Xbox headset support.

According to MSDN, "the combination of the left and right triggers in DirectInput is by design. Games have always assumed that DirectInput device axes are centered when there is no user interaction with the device. However, the Xbox 360 controller was designed to register minimum value, not center, when the triggers are not being held." MSDN proffered the "solution" of combining the triggers, setting one trigger to a positive direction and the other to a negative direction, so no user interaction is indicative to DirectInput of the "control" being at center.

The above, however, ignores the fact that many DirectInput controllers, such as gamepads with dual analog sticks and racing-wheel controller sets, already map triggers and pedals independently. In addition, many DirectInput devices also have vibration effects. At least one 3rd-party driver, XBCD, gives the Xbox 360 controllers the vibration support, dead zones and (optionally) independent analog/digital triggers through DirectInput its XInput driver possesses. This suggests that Microsoft's Xbox 360 controller driver was given ''intentionally'' weaker DirectInput support, rather than due to any differences between DirectInput and XInput APIs. On the other hand, Xbox 360 controllers using XInput support only very basic control of vibration motors in contrast with greater palette of effects supported via DirectInput.

DirectInput vs XInput

Advantages of DirectInput over XInput:
* XInput supports only controllers that work with the Microsoft Xbox console
* XInput supports a maximum of four controllers at a time. DirectInput has no such limit
* XInput does not support keyboards, mice, or mouse-type devices. While this mirrors Microsoft's recommendation not to use DirectInput with these devices, programmers can use DirectInput with these devices.
* XInput supports maximum of 4 axes, 10 buttons, 2 triggers and 8-direction digital pad per controller, compared to DirectInput's support for 8 axes, 128 buttons, and full-range POV. (The number of axes, buttons and triggers XInput supports corresponds directly to the Xbox 360 controller.)

Advantages of XInput over DirectInput:
* Currently supported by Microsoft

References

External links

Microsoft's DirectInput documentation

XInput and DirectInput

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