X9

This is a short chapter. To make the player follow the mouse when the mouse button is held, we need to go back to the PlayerTick function. Determining if the mouse is hold and not clicked is tricky, we need to specify a time interval  for mouse down and mouse up. Replace the content of the PlayerTick function with this one :

/******************************************************************
 *
 *  TUTORIAL FUNCTION
 *
 *  PlayerTick is called once per frame
 *
 ******************************************************************/
event PlayerTick( float DeltaTime )
{
	super.PlayerTick(DeltaTime);

	//Set the location of the 3d marker that moves with the mouse.
	MouseCursor.SetLocation(MouseHitWorldLocation);	

	//We use the right mouse button to move, change it to suit your need !
	if(bRightMousePressed)
	{
		//accumulate the time for knowing how much time the button was pressed.
		DeltaTimeAccumulated += DeltaTime;

		//Update destination so that while holding the mouse down the destination changes
		//with the mouse move.
		SetDestinationPosition(MouseHitWorldLocation);

		//If its not already pushed, push the state that makes the pawn run to destination
		//until mouse is unpressed. Make sure we do it after the allocated time for a single
		//click or else two states could be pushed simultaneously
		if(DeltaTimeAccumulated >= 0.13f)
		{
			if(!IsInState('MoveMousePressedAndHold'))
			{
				`Log("Pushed MoveMousePressedAndHold state");
				PushState('MoveMousePressedAndHold');
			}
			else
			{
				//Specify execution of current state, starting from label Begin:, ignoring all events and
				//keeping our current pushed state MoveMousePressedAndHold. To better understand why this
				//continually execute each frame from our Begin: label, see
				//http://udn.epicgames.com/Three/MasteringUnrealScriptStates.html,
				//11.3 - BASIC STATE TRANSITIONS
				GotoState('MoveMousePressedAndHold', 'Begin', false, true);
			}
		}
	}

	//DumpStateStack();
}

Notice now that if DeltaTimeAccumulated is after the time taken into account in StopFire, we have a mouse button held down. Now because this executes each frame, we need to pop the next state only once to make the player move.

The use of !IsInState is handy to check if we are already in the said state. Remember this function is called each frame. Now the GotoState here is trycky. Since we are already in the MoveMousePressedAndHold state. We need to execute each frame from the begin label, else we are going to push a tremendous amount of states and at some point the player stop doing what you want and go in a straight line.

So to prevent this we simply instruct to jump to the Begin label, keeping the current stack the way it is and we do not fire state transitions events. I suggest you look up the function yourself to learn more. I commented the DumpStateStack() function. Its very usefull to debug stack of states at a given frame.

Add the related state :

/******************************************************************
 *
 *  TUTORIAL STATE (MoveMousePressedAndHold)
 *
 *  MoveMousePressedAndHold is the state when a mouse button is pressed
 *  and kept to move the pawn freely.
 *
 *
 ******************************************************************/
state MoveMousePressedAndHold
{
Begin:
	if(!bPawnNearDestination)
	{
		`Log("MoveMousePressedAndHold at pos"@GetDestinationPosition());
		MoveTo(GetDestinationPosition());
	}
	else
	{
		PopState();
	}
}

• Compile and execute and voila !

Get chapter 4 source code.

Chapter 5 – Pathfinding for the champions