Actionscript 2 - hitTesting multiple instances - actionscript

Question

I'm making a platformer using Actionscript 2. I got the jumping and gravity and everything going, but I'm limited to one "ground". As one might imagine, platformers require multiple "grounds" for jumping onto and falling off of. I tried editing the "ground" movie clip so that it was several blocks with nothing between them, but when I try this, my character will jump, land at the peak of its jump, and repeat the process until it lands on the top of the ground movie clip, then behave regularly, jumping and landing on top of the ground movieclip, even if there's no part of the ground movieclip to land on.
Here's my ground-gravity code.
if(this.hitTest(_root.ground))
{
this._y -= gravity;
gravity = 0;
jumping = false;
}

Answer 1

When you use hitTest between two MovieClips, it doesn't matter if there's nothing inside the movieclip, as long as the hittesting movieclip is INSIDE the bounding box (the blue outer rectangle of a movieclip when you select it) of the other movieclip.
To solve your problem, but still have many grounds in the same MovieClip, you have to use the second usage of hitTest, hitTest(x, y, shapeFlag) -- this will not check if two movieclips are hittesting each other, but rather if a MovieClip is touching a POINT (just an x and a y coordinate). But the real advantage of using this is the third parameter, shapeFlag, which is a Boolean value (either true or false) -- if it's false, then the hitTest will take the whole movieclip into account, meaning that even if there are empty spaces, those will be included in the hitTest, WHILE, if it's true, then only the actual shape of the MovieClip will be considered during the hitTest.
First of all, you have to get inside your Character's MovieClip and move him so that the registration point of the movieclip (you know that small plus sign), is at the BOTTOM of your character. Then, change your code to this:
if(_root.ground.hitTest(this._x, this._y, true))
{
this._y -= gravity;
gravity = 0;
jumping = false;
}
This will check if the SHAPE of the ground MovieClip (meaning only the platforms, NOT the empty spaces between them) are touching the registration point of your MovieClip, which is located at the bottom, at the feet, of your character. So, whenever the feet of your character are touching any of the platforms inside the ground movieclip, the code will be executed and your character wil stop.
Hope this helps :)