Example #1
0
  /**
   * Take a time step. This performs collision detection, integration, and constraint solution.
   *
   * @param timeStep the amount of time to simulate, this should not vary.
   * @param velocityIterations for the velocity constraint solver.
   * @param positionIterations for the position constraint solver.
   */
  public void step(float dt, int velocityIterations, int positionIterations) {
    stepTimer.reset();
    // log.debug("Starting step");
    // If new fixtures were added, we need to find the new contacts.
    if ((m_flags & NEW_FIXTURE) == NEW_FIXTURE) {
      // log.debug("There's a new fixture, lets look for new contacts");
      m_contactManager.findNewContacts();
      m_flags &= ~NEW_FIXTURE;
    }

    m_flags |= LOCKED;

    step.dt = dt;
    step.velocityIterations = velocityIterations;
    step.positionIterations = positionIterations;
    if (dt > 0.0f) {
      step.inv_dt = 1.0f / dt;
    } else {
      step.inv_dt = 0.0f;
    }

    step.dtRatio = m_inv_dt0 * dt;

    step.warmStarting = m_warmStarting;

    // Update contacts. This is where some contacts are destroyed.
    tempTimer.reset();
    m_contactManager.collide();
    m_profile.collide = tempTimer.getMilliseconds();

    // Integrate velocities, solve velocity constraints, and integrate positions.
    if (m_stepComplete && step.dt > 0.0f) {
      tempTimer.reset();
      solve(step);
      m_profile.solve = tempTimer.getMilliseconds();
    }

    // Handle TOI events.
    if (m_continuousPhysics && step.dt > 0.0f) {
      tempTimer.reset();
      solveTOI(step);
      m_profile.solveTOI = tempTimer.getMilliseconds();
    }

    if (step.dt > 0.0f) {
      m_inv_dt0 = step.inv_dt;
    }

    if ((m_flags & CLEAR_FORCES) == CLEAR_FORCES) {
      clearForces();
    }

    m_flags &= ~LOCKED;
    // log.debug("ending step");

    m_profile.step = stepTimer.getMilliseconds();
  }