Processing N1

// Main
Animal a1;

void setup() {
  size(500, 400);
  background(0, 0, 0);
  a1 = new Animal(new PVector(3, 6));
  a1.applyGravity(new PVector(0, 9));
}

void draw() {
  clear();
  a1.update();
}

void mouseClicked() {
  a1.applyVecodity(new PVector(mouseX, mouseY));
}

// Animal (class)
class Animal {

  PVector position;
  PVector speed;
  PVector acceleration;

  // TODO add mass

  void applyVecodity(PVector mouseClickPosition) {
     PVector newVelocity = mouseClickPosition.sub(position);
     speed.x += newVelocity.x;
     speed.y += newVelocity.y;
  }

  void checkBounds() {
    if (position.x > width) {
      speed.x *= -1f;
      position.x = width-1;
    }
    if (position.x < 0) {
      speed.x *= -1f;
      position.x = 0;
    }
    if (position.y > height) {
      speed.y *= -1f;
      position.y = height-1;
    }
    if (position.y < 0) {
      speed.y *= -1f;
      position.y = 0;
    }
  }

  void applyGravity(PVector g) {
      acceleration.x = g.x;
      acceleration.y = g.y;
  }

  void update() {
    checkBounds();
    speed = speed.add(acceleration);
    position = position.add(speed);
    pushMatrix();
    translate(position.x, position.y);
    stroke(255, 0, 0);
    ellipse(0, 0, 30, 30);
    popMatrix();
  }

  Animal(PVector initialSpeed) {
    speed = new PVector();
    acceleration = new PVector();
    position = new PVector();
    speed.x = initialSpeed.x;
    speed.y = initialSpeed.y;
  }


}