step method

@override void step(double dt, { int collisionSteps = 1, })

Advances the simulation by dt seconds, in collisionSteps passes (one per 1/60 s is plenty). Characters move in moveCharacter, before it.

Implementation

@override
void step(double dt, {int collisionSteps = 1}) {
  if (_disposed || dt <= 0) return;
  steps++;
  lastStep = dt;
  final all = bodies.values.toList(growable: false);
  for (final b in all) {
    if (!b.awake) continue;
    if (b.type == BodyType3D.kinematic) {
      final target = b._kinematicTarget;
      if (target != null) {
        b.position.setFrom(target);
        b._kinematicTarget = null;
      } else {
        b.position.addScaled(b.linearVelocity, dt);
      }
      // A sensor makes no contact, so it wakes nothing (Jolt wakes bodies
      // only as it makes contacts).
      if (collisions && !b.isSensor && b.linearVelocity.lengthSquared > 0) {
        _wakeTouched(b, all);
      }
      // Still for long enough, it sleeps, as in Jolt.
      if (b.allowSleeping &&
          target == null &&
          b.linearVelocity.lengthSquared < 0.05 * 0.05) {
        if (++b._restSteps > _sleepSteps) _fallAsleep(b);
      } else {
        b._restSteps = 0;
      }
      continue;
    }
    if (b.type != BodyType3D.dynamic) continue;
    final v = b.linearVelocity;
    // Moving before this step's gravity: at rest, it wakes nothing.
    final moving = v.lengthSquared >= 0.05 * 0.05;
    v.addScaled(_gravity, b.gravityFactor * dt);
    v.addScaled(b.force, dt / b.mass);
    b.force.setZero();
    b.torque.setZero();
    v.scale(math.max(0.0, 1 - b.linearDamping * dt));
    b.position.addScaled(v, dt);
    if (collisions) _resolve(b, all, wake: moving);
    if (b.allowSleeping && v.lengthSquared < 0.05 * 0.05) {
      if (++b._restSteps > _sleepSteps) _fallAsleep(b);
    } else {
      b._restSteps = 0;
    }
  }
  if (collisions) _findContacts(all);
}