constrain dragging to 45 degree line

[durks]

how would i constrain dragging an object along a 45 degree angle

ive seen tutorials on how to duplicate mc's and position the dragged object that way, but i thought this would be easier seeing that the object follows a constant path

thanks

[^1letser]

I think something like this would do:

on the movie clip you want to drag, place this action
onClipEvent (load) {
x1 = _x;
}
onClipEvent (enterFrame) {
x2 = _x;
this._y += (x1-x2);
}



^1letser

[durks]

hmmm, i placed a mc on the stage and placed this code on the mc

onClipEvent (load) {
x1 = _x;
}
onClipEvent (mouseDown) {
if (hitTest( _root._xmouse, _root._ymouse, false)) {
startDrag ("");
}
}
onClipEvent (enterFrame) {
x2 = _x;
this._y += (x1-x2);
}


when i clicked on the mouse it shot straight up and vanished, although playing with it a little longer a managed to keep it on screen when i moved the mouse a lot slower

thanks for you help so far

[Leo Lima]

First, it will depend on where your 45 is, in which quadrant. But let's assume that you are on the first on, y>0, x>0, so your 45 graph is y = x. With that in mind, you can build something like

onClipEvent (load) {
  x0 = this._x;
  y0 = this._y;
  angle = 1;     // to switch the direction change to -1

  function YinX(x) {
    //will return the Y position about the X that enters.
    return (angle * (x - x0) + y0);
  }
}

onClipEvent (enterFrame) {
  if (drag) {
    this._x = _root._xmouse;
    this._y = YinX(this._x);
  }
}

onClipEvent (mouseDown) {
  if (this.hitTest(_root._xmouse, _root._ymouse)) 
    drag = true;
}

onClipEvent (mouseUp) {
  drag = false;
}

This works just fine.

Regards,
Leo Lima

[^1letser]

I see the problem but I haven't got much time to solve it. you can use the code by Leo Lima, it will work just fine.

sorry about the code,
^1letser

[Leo Lima]

You just forgot to consider y0. That's a simple algebra problem, about finding the equation of a straight line.

Regards,
Leo Lima

[durks]

nice one Leo Lima!!!

that works a treat, much faster than the one ive developed myself.

i ended up duplicating a load of mcs to create the 45 degree line and then positioning the draggable object to them....tedious and messy

thanks