Move to point?

How to i move a mc to a specific point from any ponit on the stage.

That i want to for the mc to move at the same speed to the destination ?

i know how to make it ease in but thats not what i want. What i want is to move at a steady speed.

FOR EASING: i used this

targetx = 0;
targety = 400;

_x += (targetx - _x)/speed;
_y += (targety - _y)/speed;

That eases into the position. What i want is to move at say a speed of 5.

I believe that I have a solution for this problem.

It sounds like what you're wanting to do is move an object along a unit vector of magnitude 5.
I don't know much flash code (hardly any really) so bear with me.

Xpos=Xpos-"speed"*(Xpos/(sqrt(("target x position"-Xpos)^2+("target y position"-Ypos)^2)))

Ypos=Ypos-"speed"*(Ypos/(sqrt(("target x position"-Xpos)^2+("target y position"-Ypos)^2)))

Disclaimer: Xpos or Ypos cannot=0 otherwise your unit vector will equal zero and your MC will go nowhere. Also your MC cannot actually reach it's destination otherwise you'll be diving by 0 and that's bad.

I hope this helps.
-Swim'nSasquatch

Calculate once when target is specified:
speed = 5;
distance_x = target._x - this._x; //find horizontal distance
distance_y = target._y - this._y; //find vertical distance
initial_distance = Math.sqrt(dx*dx+dy*dy);
step_x = distance_x/initial_distance;
step_y = distance_y/initial_distance;

While moving:
onEnterFrame = new Function()
{
var dx = target._x - this._x;
var dy = target._y - this._y;
var current_distance = Math.sqrt(dx*dx+dy*dy);
if(Math.floor(current_distance) > 0)
{
this._x += step_x*speed;
this._y += step_y*speed;
}
else
{
delete this.onEnterFrame;
}

}

I think the "initial_distance" variable in artyom_ch's post above should contain distance_x's instead of dx's. And with the y's as well, so...

Code:

---

(all on one line)

initial_distance = Math.sqrt
(distance_x*distance_x+distance_y*distance_y);

---

That makes it move towards the point in question at a constant speed.

However, it doesn't stop when it gets there. You are assuming that when it get's there the Math.floor(current_distance) inside the onEnterFrame if statement will be 0. But most likely it'll be some 'orrible floating point number.

Not quite figured out the best way to check if gone past point yet, but if i do before anyone else i'll let you guys know...

Duh! Simplest version i think would be this

Code:

---

onMouseDown = function() {
        speed = 5;
        targetx = _root._xmouse;
        targety = _root._ymouse;
        distance_x = targetx - this._x; //find horizontal distance
        distance_y = targety - this._y; //find vertical distance
       
        hyp = distance_x*distance_x+distance_y*distance_y;
        initial_distance = Math.sqrt(hyp);
       
        step_x = speed*distance_x/initial_distance;
        step_y = speed*distance_y/initial_distance;
};

onEnterFrame = function()
{
        this._x += step_x;
        this._y += step_y;
       
        if ((Math.abs(this._x - targetx) < step_x) || (Math.abs(this._y - targety) < step_y)) {
                this._x = target_x;    // just to make sure it ends up where we want :D
                this._y = target_y;
                // or, ya know, just stop. Otherwise it'll never move again!
                delete this.onEnterFrame;
        }
       
};

---

That should work. (I hope!)


[EDIT] Sorry, just a quick notE, i used the mouse (x,y) to test this, so that's why there's a onMouseDown. Change that to whatever is choosing the point [/EDIT]

to jonmack: quite right about initial_distance - its' spelling bug, in fact i ment those.

Quote:

---

However, it doesn't stop when it gets there. You are assuming that when it get's there the Math.floor(current_distance) inside the onEnterFrame if statement will be 0. But most likely it'll be some 'orrible floating point number

---

It won't in fact since Math.floor() returns it integer.

Quote:

---

this._x = target_x; this._y = target_y; // just to make sure it ends up where we want

---

Nice. Makes it pixel-perfect :D

Quote:

---

// or, ya know, just stop. Otherwise it'll never move again!

---

I've used 'delete' just to prevent unnesessary usage of system resourses. May be used like follows:

//encapsulated function
function Move(target_x,target_y)
{
...
}

onMouseDown = function()
{
//we only assign, when reaches the destination - automatically cleans up
this.onEnterFrame = Move(_xmouse,_ymouse);
}
While your method will produce constant slow-down.

:D Bug in your version:
((Math.abs(this._x - targetx) < step_x) || (Math.abs(this._y - targety) < step_y)) won't work.
Should be:

((Math.abs(this._x - targetx)) < step_x) || (Math.abs(this._y - targety)) < step_y))
:D

[[[You've lost brakets]]]

Oh yeah - you're right about the Math.floor. Silly me. But when i tried it it never seemed to stop, so something was still not quite right.

About the delete onEnterFrame; - yeah, i see what you meant now, you're idea is better for system resources. I thought you meant permanently delete it when it get's to the point - so it'll never move again. Good idea. ;)

And finally - Re: last post. Are you sure that my {}()b r[acket)]['s don't work? I'm normally good with them :D I'm sure my version works too. In fact i know they do, it works every time on my computer. Your extra brackets just makes it absolutely sure what happens first, that's all. Mine's still good, mine's still good! :)

Right, so between us we got it all working and system resource friendly then??

P.S. - more system resource (ever so slight) - my variable "hyp" doesn't need to be there really - i thought i might have needed it later, but i didn't in the end. Can get rid of that out of memory i guess.

Thanks Heaps guys it works like a charm.I hope to have the current project finished in the next week or so so i can show you how much you helped :).