I am writing a sketch that displays a grid of circles that interact with the mouse cursor to change the size of the circles depending on the location of the mouse x and y. I have two classes: one for the circles and one for the force that manipulates the circles. Right now it does what I want it to do with a single force and then the up and down arrows control the range of the force. But I want to be able to use multiple forces at once. So I want to be able to click the mouse and lock the force in its current position and then get a new force that can be put anywhere in the field of circles and locked in its position with a mouse click and then get a new force and so on.

I am new to Processing and I finding it difficult to understand how this would be structured exactly. I have tried numerous ways using mousePressed() (within void draw, within the Force class, as void mousePressed, etc.) but I am not sure if I am doing it correctly or if I am even writing the sketch in a way that will make it do what I want.

So here is the sketch and any help would be greatly appreciated. You will see mousePressed the sketch but it is not doing anything at the moment.

Circle [] cir = new Circle [900];
Force fr;

void setup() {
 size(870 ,870);
 smooth();
 for(int i = 0; i < cir.length; i++) {
 cir[i] = new Circle((i % 30) * 30, (i / 30) * 30, 30);
 fr = new Force(2,2);
 }
}

void draw() {
 background(220);
   for(int i = 0; i < cir.length; i++){
 cir[i].display();
 fr.force();
 if (mousePressed) {
   fr.force();
 }
   }
}


class Circle {
 float x, y, diameter;
 float d = 10;
 
 Circle(float xpos, float ypos, float dia) {
   x = xpos;
   y = ypos;
   diameter = dia;
 }
   void display() {
   fill(255);
   stroke(1);
   ellipse(x,y,diameter,diameter);
   diameter = (dist(fr.a, fr.b, x, y)/d);
   if (keyPressed) {
     if (keyCode == UP) {
       d+=1;
     } else if (keyCode == DOWN) {
       d-=1;
     } if (d < 1) {
       d = 1;
     }
   }
 }
}

class Force {
 float a, b;
 
 Force(float apos, float bpos) {
   a = apos;
   b = bpos;
 }
 
 void force() {
   fill (255,0,0);
    noStroke();
     ellipse (a, b, 10, 10);
   
   a = mouseX;
   b = mouseY;
 }
}

Thank you. It does run with a little less lag now.