Understanding this piece of code

Hi all,

I have got some code, but don't quite understand all the lines, any chance of helping me out?

Code

var grav:Number = 0;

var speed:Number = 5;

var jumpHeight:Number = 13;

}

//initalise variables to be used to move and jump

onClipEvent (enterFrame) {
grav++;

_y += grav;

while (_root.ground.hitTest(_x, _y, true)) {
_y--;

grav = 0;
}

// don't quite understand what this does

if (Key.isDown(Key.RIGHT)) {
_x += speed; //move to the right

} else if (Key.isDown(Key.LEFT)) {
_x -= speed; //move to the left

}
if (Key.isDown(Key.UP) && _root.ground.hitTest(_x, _y+3, true)) {  // what does y+3 do?

grav = -jumpHeight;
_y -= 4;  // if y-=4 is removed it makes no effect

}
}

• 1. Re: Understanding this piece of code

Code

var grav:Number = 0;

var speed:Number = 5;

var jumpHeight:Number = 13;

}

//initalise variables to be used to move and jump

onClipEvent (enterFrame) {
grav++;

_y += grav; // with above line accerlates this movieclip towards stage bottom

while (_root.ground.hitTest(_x, _y, true)) {  // if this movieclip "hits" _root.ground
_y--; // move up.  this repeats until this movieclip no longer "hits" _root.ground

grav = 0;
}

// in total this stops your movieclip's acceleration towards stage-bottom and prevents it from being below ground

if (Key.isDown(Key.RIGHT)) {
_x += speed; //move to the right

} else if (Key.isDown(Key.LEFT)) {
_x -= speed; //move to the left

}

//this hittest checks if this movieclip is within 3px above the ground.  ie, almost hitting
if (Key.isDown(Key.UP) && _root.ground.hitTest(_x, _y+3, true)) {  // what does y+3 do?

grav = -jumpHeight;

// if you don't see the effect of the below, it's because other code continues moving this movieclip up
_y -= 4;  // if y-=4 is removed it makes no effect

}
}