Unreal Script - Sprinting and Crouching

Unreal Script - Sprinting and Crouching

Posted on December 13, 2010 by Lucas

Anyone who has played a first person shooter game knows the importance of sprinting and crouching – in some cases, it’s the difference between getting shot and not. In theory, setting up a sprint or crouch function in the UDK is quite simple – you basically need to change the speed/height of the pawn while a key is pressed (or on a toggle if the player desires)

Fortunately, the UDK already includes a “crouch” function, which is horribly (in my opinion) bound to ‘C’ – I know, most people like this, I prefer Left CTRL. So to fix it in my bindings, I needed to change

.Bindings=(Name="LeftControl",Command="GBA_Jump")

to read

.Bindings=(Name="LeftControl",Command="GBA_Duck")

For sprinting, this is a little more involved, as most games employ a mechanic that allows a player to tire when running – additionally, a player cannot fire while running as they’d spray bullets everywhere. In effect, this is really simple to do, and involves adding the following to your Pawn class (which I assume you have already extended from UTPawn)

//Sprint handling variables
var float SprintSpeed;
var float WalkSpeed;

var float Stamina;
var float SprintTimer;
var float SprintRecoverTimer;
var float Empty;
var bool bSprinting;

exec function startSprint()
{
GroundSpeed = SprintSpeed;
bSprinting = true;
if(GroundSpeed == SprintSpeed)
{
StopFiring();
setTimer(SprintTimer, false, 'EmptySprint');
}
}

exec function stopSprint()
{
GroundSpeed = WalkSpeed;
}

simulated function EmptySprint()
{
Stamina = Empty;
GroundSpeed = WalkSpeed;
bSprinting = true;
setTimer(SprintRecoverTimer, false, 'ReplenishStamina');
}

simulated function ReplenishStamina()
{
Stamina = 10.0;
bSprinting = false;
}

defaultproperties
{
GroundSpeed=200.0
AirSpeed=200.0

//Overrides for Zombies game
WalkSpeed=280.0
SprintSpeed=500.0
SprintTimer=6.0
SprintRecoverTimer=4.0
Stamina=6.0
Empty=1
}

This relies on a key binding change in the DefaultInput.ini file, where you can add this line:

.Bindings=(Name="LeftShift",Command="StartSprint | OnRelease StopSprint")

Once compiled, you can hold the Left Shift key to sprint, or Left Control to crouch. This example is pretty noticeable, mainly as I don’t have any animations for my first person weapons, but if you do, just change the SprintSpeed and WalkSpeed properties to whatever you like and see the difference.