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Pygame - Completely Removing a Sprite from Memory


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#1 PaladinJohn   Members   -  Reputation: 130

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Posted 16 January 2013 - 02:23 PM

Hello!

I'm working on a Breakout style game, and after much testing I've pinpointed my exact problem. Sprites that I've given the .kill() command to and removed from all groups are still persistent in memory and causing issues. Below are a few excerpts of my code, and I'd appreciate if someone could point me in the direction of a better command to use, or perhaps a logic error in my coding.

 

(Note:

spell = ball

shield = paddle)

 

The root of the problem

 

I decided to add some simple items to enhance gameplay. This particular item is supposed to split your ball into three:

 

def itemEffects(self):
    if len(self.spellSprites) == 1:
        if self.spell.angle == 30 or self.spell.angle == 45 or self.spell.angle == 60:
            tempSpellx = self.spell.rect.x
            tempSpelly = self.spell.rect.y
            tempSpellSpeed = self.spell.speed
            tempSpellAngle = self.spell.angle
            self.spellSprites.empty()
            j = 30
            for i in range (0,3):
                self.spell = Spell(self.shield)
                self.spell.setStats(True, tempSpellx, tempSpelly, tempSpellSpeed, j)
                self.spell.setVelX(self.spell.angle)
                self.spell.setVelY(self.spell.angle)
                self.spellSprites.add(self.spell)
                j += 15

Directional movement is locked on 12 seperate angles, 3 for each quadrant. This code checks the quadrant, saves the current balls relevant stats to a temporary variable, clears the entire ball sprite group, then creates three new balls given the saved stats with the three angles for that quadrant. I believe the problem is that the first sprite created in this group remains in memory even after it's .kill() function is invoked.

 

Ball Death

 

Here is the code for when a ball meets it's untimely demise:

 

for theSpell in self.spellSprites:
    if theSpell.rect.centery > 540:
        if len(self.spellSprites) <= 1:
            LIVES -= 1
            self.loadLives()
            self.shield.reset()
            theSpell.kill()
            self.spellSprites.empty()
            self.spell = Spell(self.shield)
            self.spellSprites.add(self.spell)
            self.itemSprites.empty()
            if LIVES < 0:
                SCORE = 0
                LIVES = 2
                self.showTextScreen('Game Over!', 'Press Escape to Quit or Any Key to Play Again.', 2)
        else:
            theSpell.kill()

I thought this would be sufficient to destroy a ball and make everything work ok. Instead, it would appear that the first ball stays in memory.

 

I came to this conclusion because when there is one ball remaining, and the length of the spellSprites group is equal to 1, occasionally when I obtain a power up to split the balls, the current ball will disappear and a life will be lost as if the ball was out of bounds. It is my belief that the extra balls are spawning off of the primary spell who's location is far below paddle, thus instantly trigerring a loss of life as all balls are lost.

 

The Question

 

Is there a way to permenantly delete a sprite out of memory? If not, is there a way that I can access specific sprite objects within the sprite group when they all share the same name? If that's not possible either, is there some other way I can go about trying to solve this problem that I may have overlooked?

 

If there is any other information or code necessary to provide in order to solve this issue, let me know. Thank you for your time and I greatly appreciate any help you are able to give!



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#2 smr   Members   -  Reputation: 1556

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Posted 16 January 2013 - 04:14 PM

Edit: I realized everything I said before was based on the assumption spellSprites is a list. It's not. It's a pygame sprite group. Sorry!

 

In any case, check to make sure you're not tucking away any references to these sprite instances anywhere else in your code. If you are, then this could be the source of your leak. As a diagnostic, call gc.collect() after your clean-up method. If the sprites are gone out of memory after a collection, then you could have created a circular reference somewhere between the sprite and some other object. Python uses reference counting to know when to clean up an object, but it also has a garbage collector that runs periodically that can recognize and collect objects lingering only due to circular references.


Edited by smr, 16 January 2013 - 05:09 PM.


#3 smr   Members   -  Reputation: 1556

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Posted 16 January 2013 - 04:55 PM

Edit: Removed misleading information. What happened to deleting posts?


Edited by smr, 16 January 2013 - 04:59 PM.





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