Moving Platform Tutorial

programming flash
1

1: First, open up flash. size doesn’t matter.

2: make a character. size doesn’t matter. make it a movie clip and give it the instance name “char” without quotes.

3: now make a rectangle with the rectangle tool. i usually turn off the border color. i’m using this size: W: 88.0, H: 25.00. but, size doesn’t matter here either. make it a movie clip and give it the instance name “pm1”, again, without quotes.

4: make another rectangle, this is going to be a regular platform. convert a movie clip and give it an instance name “p1”.

5: now then, add this code to the frame:

stop();
speed = 0;
maxspeed = 8;
jumpspeed = 0;
jumpheight = 15;
fall = 0;
maxgravity = 15;
platforms = 2
movplats = 1
platdistance = 0
maxdistance = 330
pxspeed = 2
restspeed = 0
_root.onEnterFrame = function() {
charx = _root.char._x;
chary = _root.char._y;
charh = _root.char._height;
charw = _root.char._width;
_root.char._x += speed;
_root.char._y += fall;
if(charx > Stage.width/2) {
_root._x = -charx+stagecentrex;
} else {
_root._x = 0;
}
if(chary < Stage.height/2) {
_root._y = -chary+stagecentrey;
} else {
_root._y = 0;
}
fall++
if(fall >= maxgravity) {
fall = maxgravity;
}
if(Key.isDown(Key.LEFT)) {
speed–;
if(speed <= maxspeed*-1) {
speed = maxspeed*-1;
}
if(_root.char._xscale > 0) {
_root.char._xscale *= -1;
}
} else if(Key.isDown(Key.RIGHT)) {
speed++;
if(speed >= maxspeed) {
speed = maxspeed;
}
if(_root.char._xscale < 0) {
_root.char._xscale *= -1;
}
} else {
if(speed > restspeed) {
speed–;
if(speed <= restspeed) {
speed = restspeed;
}
} else if(speed < restspeed) {
speed++;
if(speed >= restspeed) {
speed = restspeed;
}
}
}
if(Key.isDown(Key.SPACE) && jump == false && fall <= 1) {
jump = true;
restspeed = 0
}
if(jump == true) {
if(jumpspeed > 0) {
jumpspeed–;
fall = 0;
_root.char._y -= jumpspeed;
} else {
jump = false;
}
} else {
jumpspeed = jumpheight;
}
for(i3=1; i3<=movplats; i3++) {
mplat = _root[“pm”+i3];
_root.mplat._x += pxspeed
platdistance += pxspeed
if(platdistance >= maxdistance){

        pxspeed = -pxspeed
    }
    if(platdistance &lt;= 0){
        
        pxspeed = -pxspeed
    }
    if(_root.char.hitTest(mplat)) {
        if(chary+charh/2-1 &lt; mplat._y-mplat._height/2) {
            _root.char._y = mplat._y-mplat._height/2-charh/2-.1;
            jumpspeed = jumpheight;
            fall = 0;
            jump = false;
            restspeed = pxspeed
        }
    }
}
for(i=1; i&lt;=platforms; i++) {
    plat = _root["p"+i];
    if(_root.char.hitTest(plat)) {
        restspeed = 0
        if(charx+charw/2 &lt; plat._x-plat._width/2) {
            _root.char._x = plat._x-plat._width/2-charw/2-.1; 
            speed = 0;
        } else if(charx-charw/2 &gt; plat._x+plat._width/2) {
            _root.char._x = plat._x+plat._width/2+charw/2+.1;
            speed = 0;
        }
        if(chary+charh/2-1 &lt; plat._y-plat._height/2) {
            _root.char._y = plat._y-plat._height/2-charh/2-.1;
            jumpspeed = jumpheight;
            fall = 0;
            jump = false;
        } else if(chary-charh/2+1 &gt; plat._y+plat._height/2) {
            _root.char._y = plat._y+plat._height/2+charh/2+.1
            jumpspeed *= -1;                
        }
    }
}

}

Code Explained:

speed = 0;
maxspeed = 8;
jumpspeed = 0;
jumpheight = 15;
fall = 0;
maxgravity = 15;
: this is for the char.

platforms = 2 : this how many regular platforms you have.
umm, the more platforms you have, the instance name number goes up, like so: p1, p2, p3 etc.
this goes for the moving platforms, too.

movplats = 1 : this is how many moving platforms you have.

platdistance = 0 : this is where the moving platform starts.

maxdistance = 330 : this where the moving platform stops and starts coming back.

pxspeed = 2 : this is the speed of the moving platform.

for(i3=1; i3&lt;=movplats; i3++) {
    mplat = _root["pm"+i3];
    _root.mplat._x += pxspeed
    platdistance += pxspeed
    if(platdistance &gt;= maxdistance){
        
        pxspeed = -pxspeed
    }
    if(platdistance &lt;= 0){
        
        pxspeed = -pxspeed
    }
    if(_root.char.hitTest(mplat)) {
        if(chary+charh/2-1 &lt; mplat._y-mplat._height/2) {
            _root.char._y = mplat._y-mplat._height/2-charh/2-.1;
            jumpspeed = jumpheight;
            fall = 0;
            jump = false;
            restspeed = pxspeed : this is for the moving platform... i don't know that much about it. sorry.

i hope you can figure out the rest.

basically, i set up my scene like this.

P: means where the player is positioned.
PL: platform
MPL: where the moving platform is.

P
PL_MPL________PL

somethin like that…

once again, my first tut…
my friend taught me this on msn.