hitTests and getBounds... can't grasp it...

Most of you probably have seen the code below. I just can't figure out what it does exactly... and that makes it kinda hard to implement...

Code:

---

if (walls.hitTest(getBounds(_root).xMax, _y, true)) {
trace('hit');
}
if (walls.hitTest(getBounds(_root).xMin, _y, true)) {
trace('hit');
}
if (walls.hitTest(_x, getBounds(_root).yMax, true)) {
trace('hit');
}
if (walls.hitTest(_x, getBounds(_root).yMin, true)) {
trace('hit');
}

---

Now what I understand is that it does a hitTest of something on a mc called walls. So if the something hits walls you'll get the alert 'hit'. I believe the _x and _y values are the ones of the something.... and true is set so that it tests on shape in stead of boundry, right? But what does: getBounds(_root).yMax and so on do? Please explain...

Cheers

Hi,

getBounds returns properties that are the minimum and maximum and coordinate values of the instance specified by MovieClip for the targetCoordinateSpace parameter.

Sounds confusing huh?...... straight out of the AS help file.

Anyway,......basically, it returns the property values of the movieclips coordinate space. This means that whereever the movieclip is on stage, it occupies a certain amount of coordinate space. This can be determined by the right edge of the clip(xMax) subtacted from the left edge of the clip(xMin). Same thing for height or yMax and yMin. To see an example of this, create a movieclip on stage named "clip"......

code:

---

//assign an identifier to the clip so

//you can trace individual properties

clipBounds = clip.getBounds(_root);

//trace the horizontal coordinate space

trace(clipBounds.xMax-clipBounds.xMin);

//demo trace to show clip property matches clipBounds

trace(clip._width);

---

What is the advantage of this method? You can get the bounds of oddly shaped objects with the coordinate space they occupy. The following code tests the boundary of an oddly shaped lake movieclip and stops the boat motion if a hit is detected......

code:

---

onClipEvent (enterFrame) {

	with (_root.boat) {

		if (_root.map.hitTest(getBounds(_root).xMax, _y, true)) {

			_x -= 5;

			Speed = 0;

		}

		if (_root.map.hitTest(getBounds(_root).xMin, _y, true)) {

			_x += 5;

			Speed = 0;

		}

		if (_root.map.hitTest(_x, getBounds(_root).yMax, true)) {

			_y -= 5;

			Speed = 0;

			_root.character._y -= 5;

		}

		if (_root.map.hitTest(_x, getBounds(_root).yMin, true)) {

			_y += 5;

		} 

	}

}

---

boat bounds demo
http://ntdesigns.net/quickDemo/boatBounds.swf

Thanx for that... It was more or less what I thought...

Found a good tutorial here as well:
http://www.newgrounds.com/bbs/topic.php?id=293660

The problem was, which resulted in me thinking I didn't get the whole concept, was that I was doing a hittest between a parent and child mc... It's getting late here! 4.47am... need to go to bed... it'll come to me tomorrow!

Thanx again, and happy holidays!

Cheers