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Thread: Problem with bounce physics

  1. #1
    The Cheeze to Your Macaroni ColbyCheeze's Avatar
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    Problem with bounce physics

    I am trying to get some decent bounce physics for a game that I am working on however the ball seems to never stop bouncing:
    Ball Bounce Test

    These are defined in another file
    public static const FRICTION:Number = .5;
    public static const WORLD_GRAVITY:Number = .3;
    public static const WORLD_WIND:Number = .05;

    Any ideas on how to fix this? Here is the code:

    Code:
    private function move():void{
    			
    			//APLLY ALL FORCES TO THE GAME OBJECTS
    			//VELOCITY VARIABLE
    			
    			//Apply gravity
    			redCircle.vY += Game.WORLD_GRAVITY;
    			redCircle.vX += Game.WORLD_WIND;
    			
    			//redCircle.springToPoint(stage.mouseX,stage.mouseY);
    			
    			
    			//ADD NEW VELOCITY VECTOR TO COORDS
    			
    			//Circle
    			redCircle.newX += redCircle.vX;
    			redCircle.newY += redCircle.vY;
    			
    			//DO ANY TESTS THAT NEED TO BE DONE
    			
    			//If circle hits ground reverse Y vel
    			//and apply friction
    			if(redCircle.newY >= Game.WORLD_GROUND){
    				redCircle.newY = 400;
    				redCircle.vY *= -1;
    				redCircle.vY *= redCircle.fr;
    				redCircle.vX *= redCircle.fr;
    			}
    			
    			//Wrap circle around to other side
    			//when it hits the edge
    			var halfWidth:int = redCircle.width/2;	
    			if(redCircle.newX > Game.STAGE_WIDTH + halfWidth){
    				redCircle.newX = 0 - halfWidth;
    			}
    			if(redCircle.newX < 0 -  halfWidth){
    				redCircle.newX = Game.STAGE_WIDTH + halfWidth;
    			}
    			
    		}//end move

  2. #2
    FK founder & general loiterer Flashkit's Avatar
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    redCircle.vY *= -1;

    should be something like redCircle.vY *= -0.6 that wil reduce the bounce
    Regards Mark Fennell - Flash Kit Founder, general loiterer
    -------------------------------
    I Hate Zombies - iPhone Game | markfennell.com

  3. #3
    The Cheeze to Your Macaroni ColbyCheeze's Avatar
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    Quote Originally Posted by Flashkit
    redCircle.vY *= -1;

    should be something like redCircle.vY *= -0.6 that wil reduce the bounce
    I did do that. It is afterwards.
    redCircle.vY *= -1;
    redCircle.vY *= redCircle.fr; //redCircle.fr == FRICTION:Number = .5;

  4. #4
    FK founder & general loiterer Flashkit's Avatar
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    do a check for if the vy < say 0.2 vY = 0
    Regards Mark Fennell - Flash Kit Founder, general loiterer
    -------------------------------
    I Hate Zombies - iPhone Game | markfennell.com

  5. #5
    Senior Member tonypa's Avatar
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    You need to detect when the ball has become resting on the ground and stop adding gravity in such case.

    *set up flag ballIsResting=false
    *ball hits the floor
    *reduce vY
    *if vY < less then some number set vY=0 and set ballIsResting = true
    *add gravity only if ballIsResting is false

  6. #6
    the cheesy child bounceboy's Avatar
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    funny!!! I had the opposite problem. i wanted something (it wasn't a ball but it still worked) to continuously bounce. I have solved my problem but if you wnat i can give you my lower bounce script:

    onClipEvent(load){
    bounce = 10;
    fullbounce = 10;
    way = "down";
    wtwo = _width/2;
    htwo = _height/2;
    speed = 10;
    lr = 10;
    take = 1.1;
    wide = 550;
    wide0 = 0;
    moview = wtwo;
    }
    onClipEvent(enterFrame){
    if(way=="down"){
    _y+=bounce;
    bounce+=1;
    }else if(way=="up"){
    _y-=bounce;
    bounce-=take;
    }
    if(bounce<=0){
    way = "down";
    }
    if(_root.ground.hitTest(_x,_y+htwo,true)){
    way = "up";
    }
    }

    make the walls or objects you are bouncing off into a movieclip called "ground".

    what you need to do to mine to make the bounce lower every time is make the variable take higher. at the moment it is 1.1 but if you make it higher you'll lose your bounce and if you make it lower you'll gain bounce (which if that happens, something is wrong with the physics!)

    please tell me if this worked!

  7. #7
    Pumpkin Carving 2008 ImprisonedPride's Avatar
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    Quote Originally Posted by tonypa View Post
    You need to detect when the ball has become resting on the ground and stop adding gravity in such case.

    *set up flag ballIsResting=false
    *ball hits the floor
    *reduce vY
    *if vY < less then some number set vY=0 and set ballIsResting = true
    *add gravity only if ballIsResting is false

    To do it quickly, false and true equate to 0/1, so just do:

    Code:
    vY *= gravity*ballIsResting;
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  8. #8
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    @bounceboy: its not the first time you are bumping a dated thread- why dont you simply create new threads for the things you want to tell or share?

  9. #9
    the cheesy child bounceboy's Avatar
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    ha! last time i did that everybody complained it was pointless to show so i asked for feedback and... you know where that went!

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