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hittest y position

  • ryrocks
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Post February 16th, 2009, 1:36 pm

Hey,
I have 2 movieclip class's.
-A ball which you control
-a series of rectangles that the ball "lands" on.

using a hittest, when the ball "hits" the rectangle movieclip it stops directly on top of that rectangle.

I have 3 rectangles all linked to the same class containing the hittest.

My problem is that when I move the ball across each rectangle, it does not land in the same place each time. I believe this is because since I'm using an ENTER_FRAME event, the hitCheck doesn't coincide with the ball's true first contact, and sometimes makes the ball move a little lower than desired.

I've uploaded the .swf: http://www.activ8-3d.co.uk/ryan/test/floor.swf
(use arrow keys to control)

To overcome this I added to the hittest:
[as]
if (_ball_mc.hitTestObject(this))
{
_ball_mc.onGround = true;
}
....
if (_ball_mc.onGround)
{
_ball_mc.y = this.y - this.height - 13;
}
[/as]

_ball_mc.y = this.y - this.height - 13; is the correct position I want the ball to land each time, I thought this would have cracked it, but alas! Its such a minor problem that I didn't want to ask for help on it, but I just can't take it no more!

Here's the full code:

Ball.as document class controls the ball:

Code: [ Select ]
package
{
    import flash.ui.Keyboard;
    import flash.events.*;
    import flash.display.*;

    public class Ball extends MovieClip
    {     
        public var leftDown:Boolean = false;
        public var rightDown:Boolean = false;
        public var jump:Boolean = false;
        public var velocity:Number = 20;
        public var falling:Boolean = true;
        public var speed:int = 5;
        public var onGround:Boolean = false;
    
        public function Ball()
        {         
            stage.addEventListener(KeyboardEvent.KEY_DOWN, downDetect);
            stage.addEventListener(KeyboardEvent.KEY_UP, upDetect);
            stage.addEventListener(Event.ENTER_FRAME, moveChar);
        }
        
        public function downDetect(event:KeyboardEvent):void
        {
            if(event.keyCode == Keyboard.LEFT)
            {
                leftDown = true;
            }
            if(event.keyCode == Keyboard.RIGHT)
            {
                rightDown = true;
            }
            if(event.keyCode == Keyboard.UP && !falling)
            {
                jump = true;
            }
        }
        
        
        public function upDetect(event:KeyboardEvent):void
        {
            if(event.keyCode == Keyboard.LEFT)
            {
                leftDown = false;
            }
            if(event.keyCode == Keyboard.RIGHT)
            {
                rightDown = false;
            }
        }
        
        public function moveChar(event:Event):void
        {
            if (leftDown)
            {
                this.x -= speed;
            }
            if (rightDown)
            {
                this.x += speed;
            }
            if (jump)
            {
                this.y -= velocity;
                velocity -= 1.5;
            }
        }
    }
}
  1. package
  2. {
  3.     import flash.ui.Keyboard;
  4.     import flash.events.*;
  5.     import flash.display.*;
  7.     public class Ball extends MovieClip
  8.     {     
  9.         public var leftDown:Boolean = false;
  10.         public var rightDown:Boolean = false;
  11.         public var jump:Boolean = false;
  12.         public var velocity:Number = 20;
  13.         public var falling:Boolean = true;
  14.         public var speed:int = 5;
  15.         public var onGround:Boolean = false;
  16.     
  17.         public function Ball()
  18.         {         
  19.             stage.addEventListener(KeyboardEvent.KEY_DOWN, downDetect);
  20.             stage.addEventListener(KeyboardEvent.KEY_UP, upDetect);
  21.             stage.addEventListener(Event.ENTER_FRAME, moveChar);
  22.         }
  23.         
  24.         public function downDetect(event:KeyboardEvent):void
  25.         {
  26.             if(event.keyCode == Keyboard.LEFT)
  27.             {
  28.                 leftDown = true;
  29.             }
  30.             if(event.keyCode == Keyboard.RIGHT)
  31.             {
  32.                 rightDown = true;
  33.             }
  34.             if(event.keyCode == Keyboard.UP && !falling)
  35.             {
  36.                 jump = true;
  37.             }
  38.         }
  39.         
  40.         
  41.         public function upDetect(event:KeyboardEvent):void
  42.         {
  43.             if(event.keyCode == Keyboard.LEFT)
  44.             {
  45.                 leftDown = false;
  46.             }
  47.             if(event.keyCode == Keyboard.RIGHT)
  48.             {
  49.                 rightDown = false;
  50.             }
  51.         }
  52.         
  53.         public function moveChar(event:Event):void
  54.         {
  55.             if (leftDown)
  56.             {
  57.                 this.x -= speed;
  58.             }
  59.             if (rightDown)
  60.             {
  61.                 this.x += speed;
  62.             }
  63.             if (jump)
  64.             {
  65.                 this.y -= velocity;
  66.                 velocity -= 1.5;
  67.             }
  68.         }
  69.     }
  70. }


Ground.as class containing the hittest:
Code: [ Select ]
package
{
import flash.display.MovieClip;
import flash.ui.Keyboard;
import flash.events.*;

public class Ground extends MovieClip
{
    private var _ball_mc:MovieClip;
    private var _findStageInstances:Boolean;
    
    public function Ground()
    {
        stage.addEventListener(Event.ENTER_FRAME, hitCheck);
        _findStageInstances = true;
    }
    
    public function hitCheck(event:Event):void
    {
        if (_findStageInstances)
        {
            _ball_mc = parent.getChildByName("ball_mc") as MovieClip;
            _findStageInstances = false;
        }

        if (_ball_mc.hitTestObject(this))
        {
            _ball_mc.jump = false;
            _ball_mc.falling = false;
            _ball_mc.onGround = true;
            _ball_mc.velocity = 20;
            _ball_mc.onGround = true;
            
            stage.addEventListener(KeyboardEvent.KEY_DOWN, downDetect);
            function downDetect(event:KeyboardEvent):void
            {
                if(event.keyCode == Keyboard.UP)
                {
                    stage.removeEventListener(Event.ENTER_FRAME, hitCheck);
                    _ball_mc.jump = true;
                }
            stage.addEventListener(Event.ENTER_FRAME, hitCheck);
            }
        }
        
        if (!_ball_mc.hitTestObject(this))
        {
            _ball_mc.onGround = false;
        }     
        
        if (!_ball_mc.hitTestObject(this) && !_ball_mc.jump && !_ball_mc.onGround)
        {
            _ball_mc.y += 7;
            _ball_mc.falling = true;
        }
        
        if (_ball_mc.onGround)
        {
            _ball_mc.y = this.y - this.height - 13;
        }
    }
}
}
  1. package
  2. {
  3. import flash.display.MovieClip;
  4. import flash.ui.Keyboard;
  5. import flash.events.*;
  7. public class Ground extends MovieClip
  8. {
  9.     private var _ball_mc:MovieClip;
  10.     private var _findStageInstances:Boolean;
  11.     
  12.     public function Ground()
  13.     {
  14.         stage.addEventListener(Event.ENTER_FRAME, hitCheck);
  15.         _findStageInstances = true;
  16.     }
  17.     
  18.     public function hitCheck(event:Event):void
  19.     {
  20.         if (_findStageInstances)
  21.         {
  22.             _ball_mc = parent.getChildByName("ball_mc") as MovieClip;
  23.             _findStageInstances = false;
  24.         }
  26.         if (_ball_mc.hitTestObject(this))
  27.         {
  28.             _ball_mc.jump = false;
  29.             _ball_mc.falling = false;
  30.             _ball_mc.onGround = true;
  31.             _ball_mc.velocity = 20;
  32.             _ball_mc.onGround = true;
  33.             
  34.             stage.addEventListener(KeyboardEvent.KEY_DOWN, downDetect);
  35.             function downDetect(event:KeyboardEvent):void
  36.             {
  37.                 if(event.keyCode == Keyboard.UP)
  38.                 {
  39.                     stage.removeEventListener(Event.ENTER_FRAME, hitCheck);
  40.                     _ball_mc.jump = true;
  41.                 }
  42.             stage.addEventListener(Event.ENTER_FRAME, hitCheck);
  43.             }
  44.         }
  45.         
  46.         if (!_ball_mc.hitTestObject(this))
  47.         {
  48.             _ball_mc.onGround = false;
  49.         }     
  50.         
  51.         if (!_ball_mc.hitTestObject(this) && !_ball_mc.jump && !_ball_mc.onGround)
  52.         {
  53.             _ball_mc.y += 7;
  54.             _ball_mc.falling = true;
  55.         }
  56.         
  57.         if (_ball_mc.onGround)
  58.         {
  59.             _ball_mc.y = this.y - this.height - 13;
  60.         }
  61.     }
  62. }
  63. }


Thank you!
  • Anonymous
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Post February 16th, 2009, 1:36 pm

  • ryrocks
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Post February 17th, 2009, 9:11 am

Screw you guys, I've fixed it! (joke!)

I was close before, I was just overcomplicating things. I needed to remove the eventlistener when the hittest was detected because there was a certain point where flash thought the objects were hitting and wern't hitting at the same time :-\ Therefore it set the ball position to the desired position, but then moved it down 7px as if it were falling.
I then reattached the eventlistener after the hittest true method.

That probably didn't make any sense to you! (hard to explain!)

Anywhoooo, heres the working code:

Code: [ Select ]
public function hitCheck(event:Event):void
    {
        if (_findStageInstances)
        {
            _ball_mc = parent.getChildByName("ball_mc") as MovieClip;
            _findStageInstances = false;
        }

        if (_ball_mc.hitTestObject(this))
        {
            _ball_mc.jump = false;
            _ball_mc.falling = false;
            _ball_mc.y = (this.y);
            _ball_mc.velocity = 17;        
            stage.removeEventListener(Event.ENTER_FRAME, hitCheck);
        }
        stage.addEventListener(Event.ENTER_FRAME, hitCheck);
        
        if (!_ball_mc.hitTestObject(this) && !_ball_mc.jump)
        {
            _ball_mc.y += 4;
            _ball_mc.falling = true;    
        }
    }
  1. public function hitCheck(event:Event):void
  2.     {
  3.         if (_findStageInstances)
  4.         {
  5.             _ball_mc = parent.getChildByName("ball_mc") as MovieClip;
  6.             _findStageInstances = false;
  7.         }
  9.         if (_ball_mc.hitTestObject(this))
  10.         {
  11.             _ball_mc.jump = false;
  12.             _ball_mc.falling = false;
  13.             _ball_mc.y = (this.y);
  14.             _ball_mc.velocity = 17;        
  15.             stage.removeEventListener(Event.ENTER_FRAME, hitCheck);
  16.         }
  17.         stage.addEventListener(Event.ENTER_FRAME, hitCheck);
  18.         
  19.         if (!_ball_mc.hitTestObject(this) && !_ball_mc.jump)
  20.         {
  21.             _ball_mc.y += 4;
  22.             _ball_mc.falling = true;    
  23.         }
  24.     }
  • graphixboy
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Post February 17th, 2009, 10:22 am

Glad you fixed it. I just hadn't gotten this far down the list yet :-)
If at first you don't succeed F1... If that doesn't work try Google!
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