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From: rritchey on 5 May 2008 09:58
I recently downloaded a collision detection class from gskinner.com for an
interaction that I am making in AS2 where I needed some REAL hitTesting with 2
transparent PNG's. The class works fine testing locally by itself, but for
final release, the SWF will be loaded into a Flash interface via a Loader
component. Lockroot is set to false by default in the interface for other
reasons, but I am able to change it on the fly via a function in the interface.
Regardless of the lockroot settings, when the interaction is loaded into the
interface, the hit detection does not work. I am thinking this may have
something to do with the following 2 lines in the class:

var bounds1:Object = p_clip1.getBounds(_root);
var bounds2:Object = p_clip2.getBounds(_root);

I am wondering if the (_root) pass into getBounds is causing problems with the
different roots in the final interface. This is broken even with lockroot set
to true. I have tried changing the _root to _parent, this, and removing it
altogether. It only works outside of the interface when the _root is there,
and it doesn't work inside the interface at all. Any thoughts?

From: dzedward on 5 May 2008 10:15
what happens if you trace _root. Do you get the expected results?
From: rritchey on 5 May 2008 10:25
Why do I never think to trace things like _root.....

I traced it out, and with lockroot set to true, I do get the correct path.
(In my instance that is "_level0.loaderClip.currentPage.my_loader") But the
hit detection still breaks.

Here is my code, and the collision detection class from gskinner



my code:

function checkCollision() {

// check for collisions:
var collisionRect:Rectangle =
CollisionDetection.checkForCollision(gauge,smFront,120);

// if there is a collision:
if (collisionRect) {

drawin.clear();

with (drawin) {
beginFill(0x00FF00,20);
lineStyle(0,0x00FF00,40);
moveTo(collisionRect.x,collisionRect.y);
lineTo(collisionRect.x+collisionRect.width,collisionRect.y);

lineTo(collisionRect.x+collisionRect.width,collisionRect.y+collisionRect.heig
ht);
lineTo(collisionRect.x,collisionRect.y+collisionRect.height);
lineTo(collisionRect.x,collisionRect.y);
}

if(smFront._x > 250 && smFront._x < 390 && collisionRect.height <= 33){
smFront._x = smBack._x = 318.95;

zoomGauge._visible = bubble._visible = lgFront._visible = lgBack._visible =
true;

lgFront._y = lgBack._y = smBack._y+47;
}else if(smFront._x > 250 && smFront._x < 390 && collisionRect.height > 33){
smFront._x = smBack._x = 318.95;
smFront._y = smBack._y = 290;

zoomGauge._visible = bubble._visible = lgFront._visible = lgBack._visible =
true;

lgFront._y = lgBack._y = smBack._y+47;
}

if(smFront._x < 310){
smFront._x -= collisionRect.width;
smBack._x -= collisionRect.width;

zoomGauge._visible = bubble._visible = lgFront._visible = lgBack._visible =
false;

lgFront._y = lgBack._y = -25;
}

if(smFront._x > 330){
smFront._x += collisionRect.width;
smBack._x += collisionRect.width;

zoomGauge._visible = bubble._visible = lgFront._visible = lgBack._visible =
false;

lgFront._y = lgBack._y = -25;
}
}else{
zoomGauge._visible = bubble._visible = lgFront._visible = lgBack._visible =
false;
lgFront._y = lgBack._y = -25;
}

//match position of the back piece of the O-Ring to the front piece
smBack._x = smFront._x;
smBack._y = smFront._y;

}

smFront.onPress = function() {
this.startDrag();

interval = setInterval(checkCollision,1);

this.onMouseUp = function() {
this.stopDrag();
delete(this.onMouseUp)
clearInterval(interval);
i = 0;
while(i < 10){
this._parent.checkCollision();
i++;
}
}
}





collision detection script:

import flash.display.BitmapData;
import flash.geom.ColorTransform;
import flash.geom.Matrix;
import flash.geom.Rectangle;

class com.gskinner.sprites.CollisionDetection {
static public function
checkForCollision(p_clip1:MovieClip,p_clip2:MovieClip,p_alphaTolerance:Number):R
ectangle {

// set up default params:
if (p_alphaTolerance == undefined) { p_alphaTolerance = 255; }

_level0.debug.text = _root;

// get bounds:
var bounds1:Object = p_clip1.getBounds(_root);
var bounds2:Object = p_clip2.getBounds(_root);

// rule out anything that we know can't collide:
if (((bounds1.xMax < bounds2.xMin) || (bounds2.xMax < bounds1.xMin)) ||
((bounds1.yMax < bounds2.yMin) || (bounds2.yMax < bounds1.yMin)) ) {
return null;
}

// determine test area boundaries:
var bounds:Object = {};
bounds.xMin = Math.max(bounds1.xMin,bounds2.xMin);
bounds.xMax = Math.min(bounds1.xMax,bounds2.xMax);
bounds.yMin = Math.max(bounds1.yMin,bounds2.yMin);
bounds.yMax = Math.min(bounds1.yMax,bounds2.yMax);

// set up the image to use:
var img:BitmapData = new
BitmapData(bounds.xMax-bounds.xMin,bounds.yMax-bounds.yMin,false);

// draw in the first image:
var mat:Matrix = p_clip1.transform.concatenatedMatrix;
mat.tx -= bounds.xMin;
mat.ty -= bounds.yMin;
img.draw(p_clip1,mat, new
ColorTransform(1,1,1,1,255,-255,-255,p_alphaTolerance));

// overlay the second image:
mat = p_clip2.transform.concatenatedMatrix;
mat.tx -= bounds.xMin;
mat.ty -= bounds.yMin;
img.draw(p_clip2,mat, new
ColorTransform(1,1,1,1,255,255,255,p_alphaTolerance),"difference");

// find the intersection:
var intersection:Rectangle = img.getColorBoundsRect(0xFFFFFFFF,0xFF00FFFF);

// if there is no intersection, return null:
if (intersection.width == 0) { return null; }

// adjust the intersection to account for the bounds:
intersection.x += bounds.xMin;
intersection.y += bounds.yMin;

return intersection;
}


}

From: dzedward on 5 May 2008 10:43
what happens if you trace out the bounds?
for(var i in bounds1){
trace(i:+" "+bounds1[i]);
};

You may be grabbing the bounds of the wrong object?
From: rritchey on 5 May 2008 11:35
My trace outside of the interface:

yMax: 495.9
yMin: 45.9
xMax: 463
xMin: 157

My trace inside of the interface:

yMax: 495.9
yMin: 45.9
xMax: 463
xMin: 157

So, the bounds appear to be getting set properly.

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