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UE3 Home > User Interfaces & HUDs > Scaleform GFx > bCaptureInput, AddCaptureKey and AddFocusIgnoreKey Guide

bCaptureInput, AddCaptureKey and AddFocusIgnoreKey Guide


Input needs to be filtered so that when the player does press a button or move an analogue stick the correct response is given. This improves the usability of the user interface dramatically.


Setting this to true in the default properties of your class will send all input (mouse, keyboard, and game controller) to the Flash class/SWF, instead of the game. Setting it to false allows all input to go to the game instead.

  bCaptureInput=true or false


If you set bCaptureInput to true, you can exclude individual keys from being capture by the SWF file and instead allow them to pass through to the game using AddFocusIgnoreKey.



If you set bCaptureInput to false, you can include individual keys to be captured by the SWF file, instead of allowing them to pass through to the game.


Example List of Capturable Keys

The following list should be used when capturing or ignoring keys:

  • 1 - 0, A - Z, F1 - F12
  • Up, Down, Left, Right
  • Spacebar, Enter, Escape
  • BackSpace, LeftControl, RightControl
  • LeftShift, RightShift, PageUp
  • PageDown, Home, Insert
  • Equals, Minus, Tab
  • LeftAlt, RightAlt

In Kismet, however, when using the Set GFx Captured Keys node, you may need to use the spelled out names of numbers, instead of the digits:

  • one, two, three, ...

Intercepting Input in ActionScript

Once you are capturing a key(s) via UnrealScript or Kismet, you can listen for those keys in ActionScript with the following code:

import flash.external.ExternalInterface;

var keyboardInput:Object = new Object(); // creates a new object to hold keyboard input.
Key.addListener(keyboardInput); // uses the object to listen for keyboard input.

/* when a key is pressed, execute this function. */
keyboardInput.onKeyDown = function()
    /* store the keyboard input ASCII code inside 'keyPressed'. */
    var keyPressed:Number = Key.getCode();
    trace("Key Pressed" + keyPressed);

    /* Call the UnrealScript function 'KeyPressed' and send it the 'keyPressed' value. */
    ExternalInterface.call("KeyPressed", keyPressed);

The code stored in keyPressed is an ASCII value.

ALERT! Note: The preferred path for keyboard input is usually going to be binding keys to functions defined in the DefaultInput.ini file. Then these UnrealScript functions can tell Flash movie clips what to do. There are, however, some situations where you'll want specific keys at specific times to go to the Flash file instead.