hi,
i'm trying to figure out how to put this code in to a class, and then call it several times, based on random coordinates, where each class representation will act as it should.

Code:

float easing = 0.05;    // Numbers 0.0 to 1.0
float division = 0.4;   // line length in percentage
float x, y;

void setup() {
  size(400, 400);
  stroke(255);
}

void draw() {
  background(0);
  float targetX = (mouseX-(width/2))*division;
  float targetY = (mouseY-(height/2))*division;
  x += (targetX-x) * easing;
  y += (targetY-y) * easing;
  pushMatrix();
  translate(width/2, height/2);
  line(0, 0, x, y);
  ellipse(x, y, 2, 2);
  popMatrix();
}
 

now, i've been trying to do it like this, but it still doesn't seem to work. all the lines get attracted by the same coordinate - i want them to be attracted individually, based on their individual "0,0,0" ... don't know if it makes sense?

Code:

// GLOBAL -------------------------------------------------------
int boidsNumber = 50;      // number of boids
float easeVar = 0.05;      // Numbers 0.0 to 1.0
float divisionVar = 0.2;   // line length in percentage
float horizontal = 80;     // horizontal offset from screen (l/r)
float vertical = 100;      // vertical offset from screen (t/b)
float x, y;

float[] ptsX = new float[boidsNumber];    // array for start-pt X
float[] ptsY = new float[boidsNumber];    // array for start-pt Y

Boid boid1;

// SETUP --------------------------------------------------------
void setup() {
  size(500, 800);
  smooth();
  stroke(255);
  ellipseMode(CENTER);
  
  for (int i = 0; i < boidsNumber; i++) {
    ptsX[i] = random(horizontal, float(width)-horizontal);
    ptsY[i] = random(vertical, float(height)-vertical);
    x = ptsX[i];
    y = ptsY[i];
  }
  
  boid1 = new Boid(easeVar, divisionVar, x, y);
}

// DRAW ---------------------------------------------------------
void draw() {
  background(0);
  for (int i = 0; i < boidsNumber; i++) {
    pushMatrix();
    translate(ptsX[i], ptsY[i]);
    boid1.display();
    popMatrix();
  }
}

// CLASS --------------------------------------------------------
class Boid {
  float x_boid, y_boid, targetX, targetY, ease_boid, division_boid;
  
  Boid(float ease_constr, float division_constr, float x_constr, float y_constr) {
    ease_boid = ease_constr;
    division_boid = division_constr;
    x_boid = x_constr;
    y_boid = y_constr;
  }
  
  void display() {
    targetX = (mouseX-(x_boid/2))*division_boid;
    targetY = (mouseY-(y_boid/2))*division_boid;
    x += (targetX-x) * ease_boid;
    y += (targetY-y) * ease_boid;
    line(0, 0, x, y);
    ellipse(x, y, 2, 2);
  }
}
 

any ideas? thanks in advance.
/claus

One other point:  If you're passing the same easeVar and divisionVar value to all Boids you might as well leave it as a global variable and remove it from the Boid object; unless of course this is going to change in a later incarnation

More or less - it's just a habit I picked up.  I don't like to write different parameter names in the class Constructor, so the 'this' is required to reference the class variable as opposed to the parameter being passed.  Here's a demonstration:

Code:

// I've added these global variables for demonstration purposes:
float x = 1;
float y = 2;

MyClass myClassInstance;

void setup() {
  size(100,100);
  myClassInstance = new MyClass(50,30);
  myClassInstance.printMe();
}

class MyClass{
  // class properties
  float x;
  float y;

  // constructor
  MyClass(float x, float y) {
    // so 'this.x' is the class variable x and 'x' is the parameter passed in the constructor (NOT the global variable x)
    this.x = x;
    this.y = y;
  }
  
  // methods...
  void printMe() {
    // note that you don't need to use 'this.x' outside of the constructor to reference the class variable 'x'
    // (So global variable names that need to be used inside a class shouldn't clash with class variable names.)
    println("x: " + x + "  y: " + y);
  }
  
} 

I'm still fairly new to all this class-based stuff, but I'm getting there.  TBH on a large project I don't know whether I'd rely on global variables (i.e. declared before setup).  Instead I might create a class to hold them and create an instance of this class and reference the variables in the instance, even possibly passing a reference to it to other classes if necessary.  That way you know exactly where the variables are coming from and I imagine that's the approach you have to take in pure Java...

I wouldn't say I've done everything 'the right way' but my Asteroids game was built to test these principles so might be useful for reference (though I'm sure there's far better reference material out there ).