Flash - random motion and rotation - Actionscript 2
Back again, my pet tadpoles (they still haven't grown into frogs yet!). This time I am going to explain the actionscript that makes them move, turn and run from the mouse. Firstly, heres an example of what they do (move your mouse over them and watch 'em swim away):
The first thing is to create 2 movie clips, one which is the tadpole itself the other is the movie that the mouse drags with it, in my example it is a transparent square 20 pixels height / width. Drag them to the stage. Give the mouse movie an instance name, for example 'mouse_mc', and on the first frame of your flash project include the following actionscript:
var mouseListener:Object = new Object();
mouseListener.onMouseMove = function() {
mouse_mc._x = _xmouse;
mouse_mc._y = _ymouse;
}
Mouse.addListener(mouseListener);
This script basically attaches the movie to the mouse, so the mouse drags it around. This is used later for the hitTest which causes the tadpole to swim away when the mouse_mc touches it. OK, now for the tadpole. Open the tadpole movie and on it's first frame enter this actionscript:
acceleration = 20; // speed of the tadpole
newpos = function ()
{
ranx = random(600); // width of the area you want your tadpole to stay within
rany = random(400); // height of the area
};
newpos();
this.onEnterFrame = function()
{
// figure direction of movement, relative to current position
var dx = ranx-this._x;
var dy = rany-this._y;
// figure angle in radians
var ar = Math.atan2(dy,dx);
// convert to rotation in degrees
this._rotation = ar*180/Math.PI;
this._x += dx/acceleration;
this._y += dy/acceleration;
if (Math.abs(dx) < 1 || Math.abs(dy) < 1) {
newpos(); // move the tadpole
}
// if the mouse movie colides with it move in a different direction
if(this.hitTest(_root.mouse_mc)){ this.newpos();}
}
Once you have done this you can duplicate the tadpole movie clip as many times as you want, to create a whole swarm of tadpoles! Be sure to give each duplicate a unique instance name eg. t1, t2, t3 etc.
This is very cool, thank you for sharing. I can't wait to try it
Hi, I tried this out and am having trouble getting it to work. Am I supposed to have 2 different layers, one for tadpole and one for mouse_mc? Also, my transparent pixels don't seem to be attached to my mouse…
Hi Sherry
They can be on separate layers, or both the same layer, it shouldn’t matter. Did you give the movie clips instance names in the ‘properties’ panel?
Sam
Hi there, just wondering if you’d have an tips on converting this to AS3. I’m very new to Flash and have been trying to do it all day!
Thanks in advance,
bex.
very nice !!!!!!!!!!
Hi, I know this is a little late in the game and not sure if anyone is still answering questions but…
What I’m looking to do is have the sprite (tadpole) freeze on mouse over; basically a button, and resume it’s motion on rollout.
Any help is appreciated.
Thanks,
Gray
i tried it and it worked! tnx
BUT i dont understand something. The tadpoles move quite smooth with an “ease out” first of all this looks nice but i dont understand why it moves like that. Second thing is… How can i also make an “ease in” So that they start moving slowly, then get to speed, then slow down en eventually stop… ?? can anyone help??
the function called newpos() basically does the following:
1. choose a rondom point on the stage
2. rotate to face the direction of that point
3. Move toward the point while decelerating to a stop
4. Once it is not moving repeat the process
@gray
to stop them moving try changing:
if(this.hitTest(_root.mouse_mc)){ this.newpos();}
to:
if(this.hitTest(_root.mouse_mc)){
this._x = this._x;
this._y = this._y;
}
@viezzz
sorry i don’t have time to code it and test it at the moment, but you need to look at these lines of code:
this._x += dx/acceleration;
this._y += dy/acceleration;
this is the code for the deceleration.
My idea would be to calculate a halfway point between the start and end position and make the tadpole accelerate towards the halfway point, and then deccelerate away from it.
Hope this helps!
where can i get copy of whole script?
Hi.. nice work. I wanted to increase the acceleration value, but the motion stops after a while if a higher value is used.
I just don’t get it why? maybe someone can give me a hint
Sweet little function man, cheers for the explanation!