Stamina Script causes Crashing?

Questions & Answers
1

I’ve been trying to implement a Stamina system to my Sprint Script (JavaScript) but for some reason it causes my game to crash. I’ve pinpointed two instances that causes it to crash:

  1. In the following lines of code:
while (stamina < 100)//if stamina is less than 100%
	{
		while (walking)//when walking
		{
			stamina = stamina + 0.25 * Time.deltaTime;//stamina increases at 1/4th the rate it depletes
		}
	}

Whenever I try to sprint, Unity crashes.

  1. If the block above is commented out, in the following lines of code:
    switch (stamina)
	{
		case 0://if stamina fully depletes
		recover = true;//recovery mode is enabled
		break;
	}
	
	if (recover)//if in recovery mode
	{
		while (stamina < 25)//while stamina is less than 25%
		{
			speed = walkSpd;//walking speed is the max speed
			
			if (stamina >= 25)//if stamina is equal to or greater than 25%
			{
				recover = false;//recovery mode is disabled
			}
		}
	}

Unity crashes when Stamina reaches zero.

Here is my entire script:

#pragma strict

private var walkSpd : float = 4; //Walking speed value
private var jogSpd : float = 6; //Jogging speed value

private var charMotor : CharacterMotor;
private var charController : CharacterController;
var stamina : int;
private var recover : boolean;
private var walking : boolean;

function Start () 
{
	charMotor = GetComponent(CharacterMotor);
	charController = GetComponent(CharacterController);
	stamina = 100;
	recover = false;
	walking = true;
}

function Update () 
{
	var speed = walkSpd;//sets default speed to walking speed
	
	if (charController.isGrounded && Input.GetKey(KeyCode.LeftShift) || charController.isGrounded && Input.GetKey(KeyCode.RightShift))
	{	//if the player's character is on the ground AND he/she is pressing a SHIFT key
			
			speed = jogSpd; //the player moves at jogging speed
			stamina = stamina - 1 * Time.deltaTime; //stamina decreases over time
			walking = false; //the player is not walking
	}
	else //if the player is NOT on the ground AND holding a SHIFT key
	{
		/*speed = walkSpd;*/ //the player's speed is walking speed
		walking = true; //the player is walking
	}
	
	switch (stamina)
	{
		case 0://if stamina fully depletes
		recover = true;//recovery mode is enabled
		break;
	}
	
	if (recover)//if in recovery mode
	{
		while (stamina < 25)//while stamina is less than 25%
		{
			speed = walkSpd;//walking speed is the max speed
			
			if (stamina >= 25)//if stamina is equal to or greater than 25%
			{
				recover = false;//recovery mode is disabled
			}
		}
	}
	
	while (stamina < 100)//if stamina is less than 100%
	{
		while (walking)//when walking
		{
			stamina = stamina + 0.25 * Time.deltaTime;//stamina increases at 1/4th the rate it depletes
		}
	}
	charMotor.movement.maxForwardSpeed =  speed; //Setting new speed variable under appropriate conditions
}

What am I doing wrong?

2

Yep, this will hang. So you start sprinting, the stamina drops below 100, so you do the while (stamina < 100) loop. But you are not walking, so stamina is never incremented, so you are stuck in the outer loop.

The solution is to not use the while() loops. In fact the way you have it structured, stamina will in a single frame go to 100. Update() gets called every frame, so you just want to do a bit of work each frame:

if (stamina < 100) {
    if (walking) {
        stamina += 0.25 * Time.deltaTime;
    }
}

And you want to do the same for your other while loop:

if (stamina < 25) {
    ...

}
3

You should read up on Coroutines. http://docs.unity3d.com/Documentation/ScriptReference/index.Coroutines_26_Yield.html I try to have all my while loops in coroutines, because then my editor won’t crash if I happen to have made an infinite loop (happens a lot).

I would start a coroutine to decrease stamina whenever a character starts moving, and another to regenerate stamina whenever it’s appropriate. But all put together the coroutine would look something like this (untested)

function UpdateStamina(){
	if (stamina <= 0)//if stamina fully depletes
	{
		recover = true;//recovery mode is enabled
		yield;
	}
	
	if (recover)//if in recovery mode
	{
		while (stamina < 25)//while stamina is less than 25%
		{
			speed = walkSpd;//walking speed is the max speed
			
			if (stamina >= 25)//if stamina is equal to or greater than 25%
			{
				recover = false;//recovery mode is disabled
			}
			yield;
		}
	}
	
	while (stamina < 100 && walking)//if stamina is less than 100%
	{
		stamina = stamina + 0.25 * Time.deltaTime;//stamina increases at 1/4th the rate it depletes
		yield;
	}
}

Remove that section in Update and put StartCoroutine("UpdateStamina"); in Start()