kmagiera

function spring(dt, position, velocity, anchor, mass = 1, tension = 300) {
 const dist = sub(position, anchor);
 const acc = divide(multiply(-1, tension, dist), mass);
 return set(velocity, add(velocity, multiply(dt, acc)));
}

kmagiera

set(velocity, add(velocity, multiply(dt, acc)));

kmagiera

const VELOCITY = 50;

function force(dt, position, velocity) {
 return set(velocity, cond(lessThan(position, 0), VELOCITY, -VELOCITY));
}

kmagiera

const POSITION_THRESHOLD = 1;

function stopWhenNeeded(dt, position, velocity, clock) {
 return cond(
   and(
     lessThan(position, POSITION_THRESHOLD),
     lessThan(-POSITION_THRESHOLD, position)
   ),
   [stopClock(clock), set(velocity, 0), set(position, 0)]
 );

kmagiera

set(position, add(position, multiply(velocity, dt)))

kmagiera

set(position, add(position, multiply(velocity, dt)))

kmagiera

const clock = new Clock();
const dt = divide(diff(clock), 1000);

kmagiera

function interaction() {
 let dragging = 0;
 let start = 0;
 let position = 0;

 return (gestureTranslation, gestureState) => {
   if (gestureState === State.ACTIVE) {
     if (dragging === 0) {
       dragging = 1;
       start = position;

kmagiera

function interaction(gestureTranslation, gestureState) {
  const start = new Value(0);
  const dragging = new Value(0);
  const position = new Value(0);

  return cond(
    eq(gestureState, State.ACTIVE),
    [
      cond(eq(dragging, 0), [set(dragging, 1), set(start, position)]),
      set(position, add(start, gestureTranslation)),

kmagiera

constructor(props) {
  super(props);

  const gestureX = new Value(0);
  const state = new Value(-1);

  this._onGestureEvent = event([
    {
      nativeEvent: {
        translationX: gestureX,