interactive "sun" and "planets"?

Unity Engine
1

hey folks!
i try to do the following in 3D.

the middle is draggable and the “planets” are connected to it. the problem are the connections. right now i have cylinders but i don’t know how to tell unity to scale these cylinders so that they stay connected to the middle (sun).

http://chris-site.de/orbital/

i have a script in aftereffects that works the same way in 2D. unfortunately my programming skills are very limited so i don’t how to translate the afx script into unity syntax.

the only thing i know is that the cylinder has to know the distance between him and the middle sphere and convert this information into an appopriate scale command.

any suggestions?

cheers.chris

2

Why not use the line renderer? Then you can just hand it the transform.position of the middle object as an end point.

3

The distance between two points is calculated by subtracting the two locations and getting the magnitude of the resulting vector:

    var distance = (pos1 - pos2).magnitude;

Unity also has a convenience function called Vector3.Distance that does the same thing:

    var distance = Vector3.Distance(pos1, pos2);

You should probably base the local scale of one of the axis of the cylinder object on this distance. Something like this:

    // this goes somewhere inside a behaviour 
    //  attached to the cylinder
    var centerBall : Transform ; // drag the center ball onto this variable
    var outerBall : Transform ; // and the other one here

    var origLength = 2.0; // the original length of the cylinder

    function Update() {
       var distance = Vector3.Distance(centerBall.position, outerBall.position);
       

       transform.localScale.z = distance / origLength;
       // You might need to change the above line 
       // to one of the below depending on how the
       // cylinder is orientated:
       //   transform.localScale.y = distance / origLength;
       //   transform.localScale.x = distance / origLength;
    }
4

hey freyr!

great! thank you for the script. it works kinda but unfortunately the cylinder gets scaled in the middle?how do i tell it to scale from the end/beginning?

right now my hierarchy is the following:

(outer)sphere:gameobject:cylinder

i use the gameobject because the “lookat” function didn’t work correctly with the cylinder. so i dropped the cylinder in the gameobject and rotated it accordingly?

is it possible to drag the middle ponit of the cylinder to the end like in standard 3d packages?

cheers.chris