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Game: Health regeneration?


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#1 Nausea   Members   -  Reputation: 257

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Posted 01 March 2013 - 04:31 PM

Hey!

So I've been working on a health bar which shrinks and grows according to how much health your character has.

The problem is I don't know how to add a smooth increment to health regen. 

Say if I want to gain 600 life over 4 seconds, how would I go about achieving this? Will I have to use float numbers, and in what way? The health bar checks how many pixels the bar should shrink and grow depending on the health value.

 

This is my code right now.

CHealthBart.cpp

void CHealthBar::OnRender(SDL_Surface* _destination)
{

	SDL_FillRect(_destination, &BarBackground, SDL_MapRGB(_destination->format, 0, 0, 0));

	if( (float)Owner->GetCurrentHealth() / Owner->GetMaxHealth() > 0.6f )
	{
		SDL_FillRect(_destination, &Bar, SDL_MapRGB(_destination->format, HighHealth.r, HighHealth.g, HighHealth.b));
	}
	if ( (float)Owner->GetCurrentHealth() / Owner->GetMaxHealth() <= 0.6f && Owner->GetCurrentHealth() / Owner->GetMaxHealth() < 0.25f )
	{
		SDL_FillRect(_destination, &Bar, SDL_MapRGB(_destination->format, AverageHealth.r, AverageHealth.g, AverageHealth.b)); 
	}
	if( (float)Owner->GetCurrentHealth() / Owner->GetMaxHealth() <= 0.25f)
	{
		SDL_FillRect(_destination, &Bar, SDL_MapRGB(_destination->format, LowHealth.r, LowHealth.g, LowHealth.b)); 
	}
	
}

void CHealthBar::OnLoop()
{

	BarBackground.x = Owner->GetX();
	BarBackground.y = ( Owner->GetY() - 5 ); 

	Bar.x = ( Owner->GetX() + 1 );
	Bar.y = ( Owner->GetY() - 4 );

	float tempw = (float)Owner->GetCurrentHealth() / Owner->GetMaxHealth();
	Bar.w = MaxBarLength * tempw;

}

 

Would be great if someone could give a good answer on this.



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#2 MrDaaark   Members   -  Reputation: 3535

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Posted 01 March 2013 - 04:45 PM


I don't 100% understand this, because you are talking about health regeneration, but posting graphics drawing code. If you increase the amount of health in the update logic, your drawing code won't have to know about it. Just draw the amount of health every frame, and it will naturally animate smoothly, because the health is animating smoothly.

const float RecoveryRate = 150.0f; //Health to recover per second (150 * 4 = 600)

Update(dt)
{
Health += (RecoveryRate * dt);
}

dt is delta time. It's the time in seconds since the last update. Every time you update your game, you should measure the time, and get the current delta time.

SDL may have a way to get the delta time automatically... I'll google something... here smile.png http://gameprogrammingtutorials.blogspot.ca/2010/01/sdl-tutorial-series-part-5-dealing-with.html

#3 Paradigm Shifter   Crossbones+   -  Reputation: 4783

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Posted 01 March 2013 - 04:46 PM

Add 600 / ( 4 / time since last frame in seconds) to your health per frame. So if you run at 60fps, add 600 / (4 / (1/60)) = 600 / (4 * 60) = 2.5 health per frame, after 240 frames (4 seconds) you will have added 2.5 * 240 = 600 health.


Edited by Paradigm Shifter, 01 March 2013 - 04:56 PM.

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#4 SiCrane   Moderators   -  Reputation: 9119

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Posted 01 March 2013 - 06:14 PM

Note that if you use these kinds of straightforward regeneration formulas it pretty much requires you to store your health in a floating point type. Otherwise, the fraction will get dropped every time you try adding to your health variable and the effective health regeneration rate will not match the desired rate. Ex: if you try adding 2.5 every frame to an int, it will only add 2, meaning that effective regeneration rate will be only 80% of desired.

#5 Alamar   Members   -  Reputation: 214

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Posted 01 March 2013 - 06:44 PM

The below is how I do this... It assumes you have Owner member variables, as floats, for Regen and Health. A few things to note: AddRegen is cumulative (if you AddRegen( 600, 4 ) as in your example, then two seconds later, do it again, the new value will be 900 over 4 seconds. If you want it to overwrite the current regen, replace += with =), AddRegen should work fine with negative regen (poison, burning, etc).
void Owner::AddRegen( float fValue, float fDuration )
{
  m_fRegenValue += fValue;
  m_fRegenDuration = fDuration;
}

void Owner::Update( float fDeltaTime )
{
  if( m_fRegenValue > 0.0f && m_fRegenDuration > 0.0f )
  {
    float fDeltaRegen = min( fDeltaTime, m_fRegenDuration );

    m_fHealth += m_fRegenValue * fDeltaRegen;
    if( m_fHealth > m_fHealthMax )
      m_fHealth = m_fHealthMax;

    m_fRegenDuration -= fDeltaRegen;
  }
}
-Alamar

#6 Nausea   Members   -  Reputation: 257

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Posted 02 March 2013 - 06:31 AM

Thank you all for your input. I finally with your help got it working. :)



#7 Shannon Barber   Moderators   -  Reputation: 1373

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Posted 02 March 2013 - 03:19 PM

With computers today it's probably faster to use floating-point than do all the shifting required for fixed-point numbers.

Just be aware that you can never use == or != with floating-point numbers as they are always imprecise by a little bit.


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#8 Nausea   Members   -  Reputation: 257

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Posted 02 March 2013 - 04:27 PM

With computers today it's probably faster to use floating-point than do all the shifting required for fixed-point numbers.

Just be aware that you can never use == or != with floating-point numbers as they are always imprecise by a little bit.

I did change my health and regen to float instead of int. :) 






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