How to return value from a class, derived from an array in Processing

Question

I'm new to Processing. I want to learn how to graph some modelling I am doing so I'm using gwoptics to do it. They have an example called RollingGraph. This basically plots out whatever you want along a time dependent scrolling x axis.

The problem is that I don't quite understand how I get it to plot what I want.

I have an array, let's say which plots ellipses randomly on a canvas and these rotate randomly every frame. How can I get the Rolling Graph to plot the sum of all the rotations, which could be circle.rot?

So far I have the best MCVE I could get:

import org.gwoptics.graphics.graph2D.Graph2D;
import org.gwoptics.graphics.graph2D.traces.ILine2DEquation;
import org.gwoptics.graphics.graph2D.traces.RollingLine2DTrace;



  class eq implements ILine2DEquation{
      public double computePoint(double x,int pos) {
       return mouseX;    //////HOW DO I GET THIS TO RETURN THE SUM OF circle.rot?????? 
      }
    }
    
    class eq2 implements ILine2DEquation{
      public double computePoint(double x,int pos) {
        return mouseY;
      }    
    }
    
    class eq3 implements ILine2DEquation{
      public double computePoint(double x,int pos) {
        if(mousePressed)
          return 400;
        else
          return 0;
      }    
    }
    
    RollingLine2DTrace roll,roll2,roll3;
    Graph2D g;


class Circle{
   public float x1; 
   public float y1;
   public float x2;
   public float y2;
   public color cB;
   public float rot;
   public float authority;
   public float fert = 1;
   public float r = x1; //radius


   public Circle(float x1, float y1, float x2, float y2, color tempcB, float rot, float authority, float fert){
          this.x1 = x1;
          this.y1 = y1;
          this.x2 = x2;
          this.y2 = y2;
          this.cB = tempcB;
          this.authority = random(255);
          this.fert = random(1);
          this.rot= random(360);
       }
    }

    public ArrayList<Circle> circles = new ArrayList<Circle>();
    
    void setup(){
      size(1000, 1000);
      frameRate(6);
      rectMode(CENTER);
      ellipseMode(CENTER);
      
      int sec = second();
      
      roll  = new RollingLine2DTrace(new eq() ,100,0.01f);
      roll.setTraceColour(0, 255, 0);
    
      
      roll2 = new RollingLine2DTrace(new eq2(),100,0.01f);
      roll2.setTraceColour(255, 0, 0);
      
      roll3 = new RollingLine2DTrace(new eq3(),100,0.05f);
      roll3.setTraceColour(255, 255, 255);
       
      g = new Graph2D(this, 400, 200, false);
      g.setYAxisMax(600);
      g.addTrace(roll);
      g.addTrace(roll2);
      g.addTrace(roll3);
      g.position.y = 50;
      g.position.x = 100;
      g.setYAxisTickSpacing(100);
      g.setXAxisMax(5f);
      smooth();
      background(204);
    
      noStroke();
      fill(255, 204,100);
           for(int i = 1; i < 48; i++){
           float r = random(100,height-200);
           float s = random(100,width-200);
           float t = 20;
           float u = 20;
           circles.add(new Circle(r,s,t,u,color(100,14,14),random(360),color(100,14,14),random(10)));
       }
    }
    
    void draw() {
      background(204);
      g.draw();
    
    for(Circle circle : circles){
      pushMatrix();
            translate(circle.x1, circle.y1);
            rotate(random(360));
            translate(-circle.x1, -circle.y1);
            fill(circle.authority);
            strokeWeight(0);
            stroke(100,0,0);
            rect(circle.x1, circle.y1, 24, 36,0, 0, 12, 18);
            popMatrix();
      }
    }

Community · Accepted Answer · 2017-05-23 11:59:29Z

If I understand your question, all you have to do is iterate over the instances and calculate the total.

First, you're going to need a data structure that holds all of your instances. You've said you're using an array, so it sounds like you've go that covered. You have to make sure that this array is in scope for the next step, so this probably means declaring it at the sketch level (not inside a function or class).

Secondly, you're going to need a for loop that iterates over the instances in the data structure. You can use a variable to add up the total. Something like this:

float total = 0;
for(Circle c : yourCircleArray){
   total += c.rot;
}

You might put that into a function so that you can call it whenever you want.

Edit: Looking at your code more closely, you actually have an ArrayList, not an array. It looks like it's already initialized at the sketch level, so all you need to do is this:

 public double computePoint() {
    float total = 0;
    for(Circle c : circles){
       total += c.rot;
    }
    return total;
 }

If you can't get that working, try creating an MCVE by eliminating your dependencies on whatever library you're importing at the top of your sketch. Remember that an MCVE is supposed to narrow it down to one specific problem (how to get a total from an array), not do your whole end goal.

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