fisica attraction

fabbot

in Contributed Library Questions • 2 years ago

Hi,
I apologize in advance for my question, for it will show you how little my coding skills are.
I am trying to create an attractor in Fisica. That means I create a bunch of fboxes randomly spread over the canvas, and want them to move towards the center of the canvas, as if the center of gravity was there. there they are supposed to collide and build a random shape. I havent found any force fields within the Librarie. I think the "addForce" Method is not what I want here, right?
Any Ideas?
Thanx a lot in Advance

Fabi

Replies(2)

dimitrie

Re: fisica attraction

2 years ago

Hey Fabi,

I've just worked on something quite similar, only with circles. Here's the code:

I created a class which extends FCircle - you can do the same for FBox. It has only one extra method, updateForce() which basically does all the magic.

public class Cell extends FCircle
{
Cell(float _rad, float px, float py)
{
super(random(10, 50));
this.setPosition(px, py);
this.setNoStroke();
this.setFill(255);
updateForce();
}
void updateForce()
{
this.resetForces();
PVector a = new PVector(this.getX(), this.getY());
PVector o = new PVector(width/2, height/2);
PVector dir = PVector.sub(o, a);
if (dir.mag() < 100)
dir.mult(100/dir.mag());
this.addForce(dir.x, dir.y);
}
}

Then in the main PApplet, just remeber to call updateForce for all the "Cells" before the world.step();

import fisica.*;
FWorld world;
ArrayList Cells;
void setup()
{
size(800, 600);
smooth();
Fisica.init(this);
world = new FWorld();
world.setGravity(0,0);
Cells = new ArrayList();
}
void draw()
{
background(50);
for(int i = 0; i < Cells.size(); i++)
{
Cell temp = (Cell) Cells.get(i);
temp.updateForce();
}
world.step();
world.draw();
}
void mousePressed()
{
Cell q = new Cell(50, mouseX, mouseY);
world.add(q);
Cells.add(q);
}

Hope it helps, d

fabbot

Re: Re: fisica attraction

2 years ago

Thanks so much Dimitrie!!!
Cool stuff. In the meantime I achieved a little something too with Distance joints. I worked my way through the "Joints" Example file. But now I have a new Ground to start from.
If youre interested in my approach I will post the code, but with a warning: Nube is producing horribly redundant spaghetticode :)
Thanks again and Cheers from Cologne, Germany
Fabi

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