Sprint Stamina

Newbie & Debugging Questions
#1

Hello, I’m new here, but I’ve been trying to get a sprint stamina system to work for a while now. I don’t think I’m going about it the correct way.

What I’ve been trying is to create a boolean method that returns true while the meter isn’t 0. What I’m having issues coming up w/ is how to design the method to count down and where to call it. I am currently trying to call the boolean method (sprintStamina()) in an if statement inside of my update method where my movement code is, like this:


if (input.run && input.right) {
	if (sprintStamina()) {
		xa = xa + 1;
	}
}

and my sprintStamina() method is where I’m having trouble coming up w/ the correct code to accomplish this. My sprintStamina() method is in shambles and very broken. I’m having trouble figuring this problem out. If anyone can help me, I’d appreciate it. If you need more detail as to what I’m trying to do, please ask.

#2

First of all, if you boolean method returns your stamina value, shouldn’t you name it more adequately? like getStamina() or hasStamina() ?

And you can set up a void method changeStamina(int value) to account for stamina changes (like grabbing some kind of stamina pill to refill it, or deplete it by running, or whatever magic you want to do)


if (/*Im pressing run, ho ho!*/) {
	//Hey, do i have enough stamina to run?
	if(hasStamina()) {
		//I DO! YAY!
		changeStamina(/*Stamina deducted for running*/);
		xa = xa + 1; //whatever this does... o_o
	}
}
#3

I would like to add that usually in a game cycle every time based event (things working over an arbitrary amount of time like slow movement from one point to another or fading out…) needs to have a momentary calculated event state. In order to do the calculation, the amount of time that has been spend since the last frame is needed. This is often called “delta”.

What that means for you: if you want to know how much stamina is used in one single frame, you have to take the time between the last frame and the current frame. Then you need to multiply this (maybe about 10 milliseconds) with a value of your choice that fits into the equation: staminaLost = milliseconds * staminaConsumptionPerMS

You need a similar equation for restoring the stamina on a time base, if this is what you like to do.

#4

This may not be entirely correct in the way someone with more experience than I would do it, but I got it to work.

Here’s what I did in my Player class:


public void update() {
	int xa = 0, ya = 0;
	if (anim < 7500) {
		anim++;
	} else {
		anim = 0;
	}
	if (input.up) ya--;
	if (input.down) ya++;
	if (input.left) xa--;
	if (input.right) xa++;
	if (input.run && input.right) {
		if (hasStamina()) {
			xa = xa + 1;
			changeStamina(1);
		}
	}
	if (input.run && input.left) {
		if (hasStamina()) {
			xa = xa - 1;
			changeStamina(1);
		}
	}
	if (input.run && input.up) {
		if (hasStamina()) {
			ya = ya - 1;
			changeStamina(1);
		}
	}
	if (input.run && input.down) {
		if (hasStamina()) {
			ya = ya + 1;
			changeStamina(1);
		}
	}
	if (xa != 0 || ya != 0) {
		move(xa, ya);
		walking = true;
	} else {
		walking = false;
	}
}
	
public int getStamina() {
	return stamina;
}

private boolean hasStamina() {
	if (stamina > 0) {
		return true;
	} else {
		return false;
	}
}

public void changeStamina(int changeAmt) {
	stamina -= changeAmt;
	System.out.println(stamina);
}

and in my main Game class I added a few lines to my run() method: To get it to update once every frame was rendered I figured it would need to be called from here so I initialized a new regenTimer and had it add to the stamina every half second in increments of 2. I bolded the lines that got the program working correctly for me.


public void run() {
	long lastTime = System.nanoTime();
	long timer = System.currentTimeMillis();
	long regenTimer = System.currentTimeMillis(); //The new regenTimer I initialized
	final double ns = 1000000000.0 / 60.0;
	double delta = 0;
	int frames = 0;
	int updates = 0;
	requestFocus();
	while (running) {
		long now = System.nanoTime();
		delta += (now - lastTime) / ns;
		lastTime = now;
		while (delta >= 1) {
			update();
			updates++;
			delta--;
		}
		render();
		frames++;

		if (System.currentTimeMillis() - timer > 1000) {
			timer += 1000;
			frame.setTitle(title + " | " + updates + " ups, " + frames + " fps");
			frames = 0;
			updates = 0;
		}

                //Added this part for the regeneration of Stamina
		if (System.currentTimeMillis() - regenTimer > 500) {
			regenTimer += 500;
			if (player.getStamina() < 100) {
				player.changeStamina(-2);
			}
		}
	}
	stop();
}

This might not be the best way for this, but I got it working, so I’m glad for that. What would be a better method to do this?

#5

Just as a suggestion for optimization purposes… I would check to see if you have stamina first before even checking the inputs…since if you don’t have stamina, your character can’t move anyways.

secondly, I would put in “else if” statements since you can’t run both left and right, and up and down… If you don’t mind, I restructured it a bit :slight_smile:

Please Note: I wrote this in notepad since I don’t have an editor here, so there’s a very real possiblity that there’s a syntax error lol.

public void update() {   
  int xa = 0, ya = 0;   

  if (anim < 7500) {      
    anim++;   
  }else{
    anim = 0;   
  }   
// -- if you don't have the stamina, don't bother checking movement inputs.   
if(hasStamina()){
  // -- check either up or down since you can move up and down at the same time.
  if (input.up){
    ya--;   
  }else if (input.down){
    ya++;
  }
  // -- check either left or right since you can't move left and right at the same time.   
  if (input.left){
    xa--;
  }else if (input.right){
    xa++;
  }

  if (input.run && input.right){     
	xa = xa + 1;         
	changeStamina(1); 
  }else if (input.run && input.left) {         
	xa = xa - 1;         
	changeStamina(1);
  }   

  if (input.run && input.up){           
	ya = ya - 1;         
	changeStamina(1);   
  }else if (input.run && input.down) {
	ya = ya + 1;
	changeStamina(1);
  }
}

if (xa != 0 || ya != 0) {
    move(xa, ya);      
    walking = true;   
} else {      
    walking = false;   
}

}

-Pickle

#6

If it works, and you know HOW it works, it’s all good. You can always refactor everything later, once you get a good grab of the code.

#7

Thanks for the help guys!! I got it working to my liking and added some of your suggestions into it. I appreciate all of your time!

#8

Rorkien is 100% right… disregard what I posted previously :slight_smile:

-Pickle

#9

Don’t! What i said actually never worked for me.
I’m the kind of person that gets depressed when he knows some piece of code isn’t on the way he likes… ;D