move inside and on edge of circle

I'm having some difficulties with setting this up...

I have two sprites - center (grey box) and target (red box)

target is moving with simple events using WSAD keys (no behaviors)

center is always lerping to target.XY and anglelerping to target.XY

speed of both lerps is based on distance(center.XY,target.XY)

It's fine in the way it works, but I don't like it when it comes to corners.

<img src="http://dl.dropbox.com/u/34375299/Construct%202/bugs%20and%20fixes/move%20around%20circle2.jpg" border="0" />

here distance A is always the same, so center is lerping to target with the same speed

<img src="http://dl.dropbox.com/u/34375299/Construct%202/bugs%20and%20fixes/move%20around%20circle3.jpg" border="0" />

but here distance B ? A and when target is in that area center speed's up and all other things I have looks "boosted".

My question is, how can I limit target distance to move only within green circle and only on the edge of that circle (blue stroke) using WSAD keys.

Would this work?

clamp(distance,0,circle radius)

Yes and no.

I've tried that already. It's indeed making the same distance to every direction, but target movement is very rough.

So, you want to constrain an 8-directional behavior to inside the circle? Why not have an invisible wall on the outside?

sqiddster check your PM ;)

think of "target" as a invisible crosshair for a "center".

Sqiddster's solution works here:

http://dl.dropbox.com/u/5426011/examples14/constrain_to_circle.capx

Yes, it's working now. I had to do some tweaks in my code to make it work.

Thanks sqiddster for idea

Thanks R0J0hound for example :)

Thanks, R0j0. I would have made an example myself but I was at school ;)

Absolute GENIUS!!!!!!!

Fabulous R0J0hound <img src="smileys/smiley20.gif" border="0" align="middle" />

is this possible with a rounded rectangle as the limit ?

same thing , kantin

just make a invisible wall around ..

Thank ou kbdmaster

yes, but rounding is fluid with the technical R0J0hound

You can make a normal rectangle the limit with clamp():

set position clamp(self.x, left,right), clamp(self.y, top,bottom)

So to do a rounded rectangle as the limit do something like this:

1. limit to a rectangle first

2. check if object is in a corner of the rectangle.

3. if it is then limit it to a circle of that corner.

How would this work with a touched object instead of keyboard.

UPDATE:

Never mind I figured it out.

constrain_to_circle_touch.capx