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UE3 Home > Input & Output Home > Key Binds

Key Binds

Overview

Key binding in Unreal Engine 3 is very flexible, and is mostly defined in the configuration file. It is works with Unrealscript, but it also has a very handy features to make things easier.

Definition

Key binds are defined within several properties.

  • Name - Name of the key bind. This can either be an alias or a mapped key.
  • Command - Command to execute when this key bind is activated.
  • Control - Control needs to be held down for this key bind to activate.
  • Shift - Shift needs to be held down for this key bind to activate.
  • Alt - Alt needs to be held down for this key bind to activate.
  • bIgnoreCtrl - If control is being held down, then this key bind is ignored.
  • bIgnoreShift - If shift is being held down, then this key bind is ignored.
  • bIgnoreAlt - If alt is being held down, then this key bind is ignored.

Key bind aliasing

Key binds are aliased when the Name doesn't match any mapped keys. Aliased key binds can then be used as a command. This was designed so that multiple keys could map to an alias (or multiple aliases). This is especially useful when the alias's command is reasonably complex or is duplicated often.

In this aliased key bind, the key bind controls how ducking / crouching is performed. The alias is called GBA_Duck, and when activated it will call Duck and set the input variable aUp to -1.0 with an absolute axis to 100. When the alias is deactivated it will call UnDuck and set the input variable aUp to -1.0 with an absolute axis of 100. 

Bindings=(Name="GBA_Duck",Command="Duck | onrelease UnDuck | Axis aUp Speed=-1.0 AbsoluteAxis=100")

Thus, to map this alias to several keys, it is done like so. In this example, crouch is mapped to the key "C" on the keyboard and the "A" button on the XBox 360 controller. 

Bindings=(Name="C",Command="GBA_Duck")
Bindings=(Name="XboxTypeS_A",Command="GBA_Duck")

Key bind chaining

Key binds defined in the configuration file can be chained to execute several commands. The pipe separator allows you to chain several exec functions together, thus binding all of these exec function to the same key. 

Bindings=(Name="BackSpace",Command="TurnAround | SwitchToRocketLauncher | StartFire")

The following commands do not have to be exec functions, and because of this you will be able to create more event based code. This key bind will execute StartFire when the left mouse button is pressed, and then execute StopFire when the left mouse button is released. This would allow you to to detect when any key is pressed and released. 

Bindings=(Name="LeftMouseButton",Command="StartFire | onrelease StopFire")

Key bind onrelease modifier

The onrelease modifier allows the key bind to only activate the following command when the key / button is released.

Key bind variables

Axis

The axis modifier sets a float variable usually within the range of -1.f and 1.f. The main exception to this range rule is if the analogue device is a mouse. They are best used for analogue style controls such as a joy stick. This variable should be defined in either Controller, Input or any of their subclasses such as PlayerController or PlayerInput. The variable should be defined as: 

var input float aMouseX; // Where aMouseX is the name of the axis

This variable can then be used like this: 

Bindings=(Name="MouseX",Command="Axis aMouseX")

Axis also has a few properties that you can append after the variable name.

  • AbsoluteAxis - This is a preprocessor to scale the input value by this multiplier over delta time. Defined as an integer.
  • DeadZone - If the absolute difference on the input has not changed by a least this value, then input is ignored.
  • Invert - This is a preprocessor to invert the input value by this amount.
  • Speed - This is the speed at which this axis is changed by.

Button

The button modifier sets a byte variable to either 0 or 1 depending on the keys status. This variable should be defined in either Controller, Input or any of their subclasses such as PlayerController or PlayerInput. The variable should be defined as: 

var input byte bAltFire; // Where bAltFire is the name of the button

This variable can then be used like this: 

Bindings=(Name="RightMouseButton",Command="Button bAltFire")

Count

This is mostly used for analogue style controls as it counts the number of samples gathered from this control and sets a byte variable to this value. The variable should be defined as: 

var input byte bXAxis; // Where bXAxis is the name of the sample count

This variable can then be used like this: 

Bindings=(Name="MouseX",Command="Count bXAxis")

This is mostly useful for performing control smoothing, such as mouse smoothing.

Toggle

This allows to automatically create a toggle using a byte as the target variable. The variable should be defined as: 

var input byte bLook; // Where bLook is the name of the variable

This variable can then be used like this: 

Bindings=(Name="L",Command="Toggle bLook")

Key bind toggle trick

You can use key binds to set new key binds. Because of this, you can create a simple toggle using just key binds. When V is first pressed, it will execute SwitchToWireframe which sets the key bind to SwitchToLit. Then when V is pressed, it will execute SwitchToLit which sets the key bind back to SwitchToWireframe. This creates a toggle-able key. 

Bindings=(Name="SwitchToWireframe",Command="viewmode wireframe | SetBind V SwitchToLit")
Bindings=(Name="SwitchToLit",Command="viewmode lit | SetBind V SwitchToWireframe")
Bindings=(Name="V",Command="SwitchToWireframe")

Key binding to Unrealscript functions

These are called exec functions. Simply put, this system allows you to map functions written in Unrealscript directly to a key. A simple exec function sample involves putting an exec function in your custom player controller.

YourPlayerController.uc 
exec function MyCustomExecFunction(int ParameterA)
{
  `Log("User executed my custom exec function with "$ParameterA);
}

Then to create a bind in the configuration file. 

Bindings=(Name="K",Command="MyCustomExecFunction")

How to set key binds in Unrealscript

You can dynamically create or reset key binds at run time within Unreal Engine 3. There are three functions inside Input that facilitate this feature.

  • GetBind(const out Name Key) - This returns a string which is the command that is currently bound to this key.
  • SetBind(const out name BindName, string Command) - This sets a key to the new command and saves it to the config.

However, these functions require access to the player input object instance. To get this, you could use. 

local PlayerController PlayerController;
local WorldInfo WorldInfo;

WorldInfo = class'WorldInfo'.static.GetWorldInfo();

if (WorldInfo != None)
{
  PlayerController = WorldInfo.GetALocalPlayerController();
  if (PlayerController != None && PlayerController.PlayerInput != None)
  {
    // You now have access to the input object instance for the local player controller
    PlayerController.PlayerInput.SetBind('J', "MyCustomExecFunction 1");
  }
}

Mappable keys

Here is a list of the keys that are mapped to Unreal Engine 3.

Keyboard

Function keys

  • F1 - Function one.
  • F2 - Function two.
  • F3 - Function three.
  • F4 - Function four.
  • F5 - Function five.
  • F6 - Function six.
  • F7 - Function seven.
  • F8 - Function eight.
  • F9 - Function nine.
  • F10 - Function ten.
  • F11 - Function eleven.
  • F12 - Function twelve.

Alphanumerical keys

  • A - Letter A.
  • B - Letter B.
  • C - Letter C.
  • D - Letter D.
  • E - Letter E.
  • F - Letter F.
  • G - Letter G.
  • H - Letter H.
  • I - Letter I.
  • J - Letter J.
  • K - Letter K.
  • L - Letter L.
  • M - Letter M.
  • N - Letter N.
  • O - Letter O.
  • P - Letter P.
  • Q - Letter Q.
  • R - Letter R.
  • S - Letter S.
  • T - Letter T.
  • U - Letter U.
  • V - Letter V.
  • W - Letter W.
  • X - Letter X.
  • Y - Letter Y.
  • Z - Letter Z.

Special keys

  • Escape - Escape.
  • Tab - Tab.
  • Tilde - ~.
  • ScrollLock - Scroll lock.
  • Pause - Pause.
  • one - One.
  • two - Two.
  • three - Three.
  • four - Four.
  • five - Five.
  • six - Six.
  • seven - Seven.
  • eight - Eight.
  • nine - Nine.
  • zero - Zero.
  • Underscore - _.
  • Equals - =.
  • Backslash - \.
  • LeftBracket - [.
  • RightBracket - ].
  • Enter - Enter or Numpad enter.
  • CapsLock - Caps lock.
  • Semicolon - ;.
  • Quote - '.
  • LeftShift - Left shift.
  • Comma - ,.
  • Period - ..
  • Slash - /.
  • RightShift - Right Shift
  • LeftControl - Left control.
  • LeftAlt - Left alt.
  • SpaceBar - Space bar.
  • RightAlt - Right alt.
  • RightControl - Right control.
  • Left - Left.
  • Up - Up.
  • Down - Down.
  • Right - Right.
  • Home - Home.
  • End - End.
  • Insert - Insert.
  • PageUp - Page up.
  • Delete - Delete.
  • PageDown - Page down.
  • NumLock - Num lock.
  • Divide - Numpad /.
  • Multiply - Numpad *.
  • Subtract - Numpad -.
  • Add - Numpad +.
  • PageDown - Page down.
  • NumPadOne - Numpad one.
  • NumPadTwo - Numpad two.
  • NumPadThree - Numpad three.
  • NumPadFour - Numpad four.
  • NumPadFive - Numpad five.
  • NumPadSix - Numpad six.
  • NumPadSeven - Numpad seven.
  • NumPadEight - Numpad eight.
  • NumPadNine - Numpad nine.
  • NumPadZero - Numpad zero.
  • Decimal - Numpad decimal.

Mouse

  • LeftMouseButton - Left mouse button.
  • RightMouseButton - Right mouse button.
  • ThumbMouseButton - Primary mouse thumb button.
  • ThumbMouseButton2 - Secondary mouse thumb button.
  • MouseScrollUp - Mouse wheel scrolling up.
  • MouseScrollDown - Mouse wheel scrolling down.
  • MouseX - Mouse movement on the X axis.
  • MouseY - Mouse movement on the Y axis.

XBox360 Controller

  • XboxTypeS_LeftThumbStick - Left thumb stick when pressed as a button.
  • XboxTypeS_RightThumbStick - Right thumb stick when pressed as a button.
  • XboxTypeS_DPad_Up - Directional pad up.
  • XboxTypeS_DPad_Left - Directional pad left.
  • XboxTypeS_DPad_Right - Directional pad right.
  • XboxTypeS_DPad_Down - Directional pad down.
  • XboxTypeS_Back - Back button.
  • XboxTypeS_Start - Start button.
  • XboxTypeS_Y - Y button.
  • XboxTypeS_X - X button.
  • XboxTypeS_B - B button.
  • XboxTypeS_A - A button.
  • XboxTypeS_LeftShoulder - Left shoulder button.
  • XboxTypeS_RightShoulder - Right shoulder button.
  • XboxTypeS_LeftTrigger - Left trigger when pressed as a button.
  • XboxTypeS_RightTrigger - Right trigger when pressed as a button.
  • XboxTypeS_LeftTriggerAxis - Left trigger when semi depressed.
  • XboxTypeS_RightTriggerAxis - Right trigger when semi depressed.
  • XboxTypeS_LeftX - Left thumb stick horizontal position when used as an analogue control.
  • XboxTypeS_LeftY - Left thumb stick vertical position when used as an analogue control.
  • XboxTypeS_RightX - Right thumb stick horizontal position when used as an analogue control.
  • XboxTypeS_RightY - Right thumb stick vertical position when used as an analogue control.