/**
 * Class: Particle
 * by: Frederic Green
 * created: 11/1/2006
 * A rudimentary class for representing a particle with
 * its own position, velocity, and acceleration. Accessor
 * and mutator methods are included for these three quantities.
 * 
 * The "move()" method governs the behavior of the particle.
 * 
 * The "render()" method governs its appearance.
 *
 */


public class Particle 
{ 

  private Vector2D position, velocity, acceleration;
  private float size;   //size of particle; in this case, the diameter of a circle
  private float pWidth;
  private float pHeight;
  private float theta = 0;

  /**
   * Default constructor (probably don't want to use this):
   */
  public Particle ()
  {
    position = null;
    velocity = null;
    acceleration = null;
    size = 0;
  }

  /**
   * Parameterized constructor expects values for position, velocity, acceleration,
   * and particle size (in that order).
   */
  public Particle (Vector2D position, Vector2D velocity, Vector2D acceleration, float pWidth, float pHeight)
  {
    this.position = position;
    this.velocity = velocity;
    this.acceleration = acceleration;
    this.pWidth = pWidth;
    this.pHeight = pHeight;
  }

  /**
   * Accessor method for getting position:
   */
  public Vector2D getPosition ()
  {
    return position;
  }

  /**
   * Accessor method for getting x-component of position:
   */
  public float getX()
  {
    return this.position.getX();
  }

  /**
   * Accessor method for getting y-component of position:
   */
  public float getY()
  {
    return this.position.getY();
  }

  /**
   * Accessor method for getting velocity:
   */
  public Vector2D getVelocity ()
  {
    return velocity;
  }

  /**
   * Accessor method for getting acceleration:
   */
  public Vector2D getAcceleration()
  {
    return acceleration;
  }

  /**
   * Reset velocity to 0:
   */
  void resetVelocity ()
  {
    velocity.reset();
  }

  /**
   * Mutator method for setting x-component of position:
   */
  public void setX (float x)
  {
    this.position.setX(x);
  }

  /**
   * Mutator method for setting y-component of position:
   */
  public void setY (float y)
  {
    this.position.setY(y);
  }

  /**
   * Mutator method for setting velocity:
   */
  public void setVelocity (Vector2D velocity)
  {
    this.velocity = velocity;
  }
  
  /**
   * Sets acceleration to 0.
   */
  public void resetAccel ()
  {
    this.acceleration.reset();
  }

  /**
   * Mutator method for setting acceleration:
   */
  public void setAcceleration (Vector2D acceleration)
  {
    this.acceleration = acceleration;
  }

  /**
   * Method for rendering the particle:
   */
  public void render ()
  {
    smooth();

    fill(200, 200, 0);
    stroke(200, 40);
    ellipse(position.getX(), position.getY(), pWidth, pHeight);
        
  } 

  /**
   * Method for moving the particle (assuming it's moving by itself):
   */
  public void move()
  {
    position = position.plus(velocity);
    velocity = velocity.plus(acceleration);
    velocity.detectCollision(position, pWidth, pHeight, width, height);
    position.constrain(pWidth/2.0, width-pWidth/2.0, pHeight/2.0, height-pHeight/2.0);
    velocity.constrain(-5, 5, -5, 5);

  }

}