Integrator.pde

class Integrator {

  final float DAMPING = 0.5f;
  final float ATTRACTION = 0.2f;

  float value;
  float vel;
  float accel;
  float force;
  float mass = 1;

  float damping = DAMPING;
  float attraction = ATTRACTION;
  boolean targeting;
  float target;


  Integrator() { }


  Integrator(float value) {
	this.value = value;
	this.target = value;
  }


  Integrator(float value, float damping, float attraction) {
	this.value = value;
	this.damping = damping;
	this.attraction = attraction;
  }


  void set(float v) {
	value = v;
	target = v;
  }

  void tick() {
	if (targeting) {
	  force += attraction * (target - value);	   
	}

	accel = force / mass;
	vel = (vel + accel) * damping;
	value += vel;

	force = 0;
  }


  void target(float t) {
	targeting = true;
	target = t;
  }


  void noTarget() {
	targeting = false;
  }
}