Super dooper pulsating circle object that DOES work. http://youtu.be/bB02W9DUqJE For Processing.

pulseSquare.pde

// init
pulseSquare follower = new pulseSquare(160, height/2, 50, 50, 50);
boolean going = true; // false is left, true is right

void setup() {
  size(640, 360);
  noStroke();
  ellipseMode(CENTER);
}

void draw() {
  background(0); // black

  // Loops the circle left and right in the range of 160-480
  if (going) {
    if (follower.getX() < 480) {
      going = true;
    } else if (follower.getX() >= 480) {
      going = false;
    }
  } else {
    if (follower.getX() <= 160) {
      going = true;
    }
  }
  
  if (going) {
    follower.updatePosition(follower.getX()+1, height/2);
  } else if (!going) {
    follower.updatePosition(follower.getX()-1, height/2);
  }

  follower.render();
}

class pulseSquare {
  // init
  float x, y;
  float w, h;
  float angle;
  
  // constructor
  pulseSquare (float x, float y, float w, float h, float angle) {
    // do not use temp vars, just use this.*
    this.x = x;
    this.y = y;
    this.w = w;
    this.h = h;
    this.angle = angle;
  }
  
  float getX() {
    return this.x;
  }
  
  float getY() {
    return this.y;
  }
  
  // slowly change color
  void oscillate() {
    angle += 0.05;
  }
  
  void updatePosition(float x, float y) {
    this.x = x;
    this.y = y;
  }
  
  // create color
  void render() {
    // this.updatePosition(mouseX, mouseY);
    this.oscillate();
    fill(127+127*sin(angle));
    ellipse(x, y, w, h);
  }
}