Android용 인스턴트 게재위치 개발자 가이드

Instant Placement API를 사용하는 방법 알아보기 활용할 수 있습니다.

기본 요건

기본 AR 개념을 이해합니다. ARCore 세션을 구성하는 방법을 알아보세요.

순간 게재위치에서 새 세션 구성

새 ARCore 세션에서 즉시 배치 모드를 사용 설정합니다.

// Create the ARCore session.
public void createSession() {
  session = new Session(applicationContext);
  Config config = new Config(session);
  // Set the Instant Placement mode.
  config.setInstantPlacementMode(InstantPlacementMode.LOCAL_Y_UP);
  session.configure(config);
}

// Create the ARCore session.
fun createSession() {
  session = Session(applicationContext);
  val config = Config(session)
  // Set the Instant Placement mode.
  config.instantPlacementMode = Config.InstantPlacementMode.LOCAL_Y_UP
  session.configure(config)
}

객체 배치

Frame.hitTestInstantPlacement() 사용 를 사용하여 화면 탭 위치에 따른 추적 가능한 인스턴트 게재위치 포인트를 만드세요. getPose() 메서드를 사용하여 현재 포즈를 가져옵니다.

private placementIsDone = false;

public void onDrawFrame(GL10 gl) {
  Frame frame = session.update();

  // Place an object on tap.
  if (!placementIsDone && didUserTap()) {
    // Use estimated distance from the user's device to the real world, based
    // on expected user interaction and behavior.
    float approximateDistanceMeters = 2.0f;
    // Performs a ray cast given a screen tap position.
    List<HitResult> results =
      frame.hitTestInstantPlacement(tapX, tapY, approximateDistanceMeters);
    if (!results.isEmpty()) {
      InstantPlacementPoint point = (InstantPlacementPoint) results.get(0).getTrackable();
      // Create an Anchor from the point's pose.
      Anchor anchor = point.createAnchor(point.getPose());
      placementIsDone = true;
      disableInstantPlacement();
    }
  }
}

var placementIsDone = false;

fun onDrawFrame(gl: GL10) {
  val frame = session.update();

  // Place an object on tap.
  if (!placementIsDone && didUserTap()) {
    // Use estimated distance from the user's device to the real world, based
    // on expected user interaction and behavior.
    val approximateDistanceMeters = 2.0f;
    // Performs a ray cast given a screen tap position.
    val results = frame.hitTestInstantPlacement(tapX, tapY, approximateDistanceMeters)
    if (results.isNotEmpty()) {
      val point = results[0].trackable as InstantPlacementPoint
      // Create an Anchor from the point's pose.
      val anchor = point.createAnchor(point.pose)
      placementIsDone = true
      disableInstantPlacement()
    }
  }
}

인스턴트 게재위치 지원 대략적인 거리로 화면 공간 추적 인스턴트 게재위치 포인트가 전환되면 전체 추적으로 자동 전환됩니다. 실생활에 얽매여 있습니다. 다음 명령어로 현재 포즈를 가져옵니다. getPose() 다음과 같이 현재 추적 방법을 가져옵니다. getTrackingMethod()

ARCore는 모든 방향의 표면에 대해 즉시 배치 히트 테스트를 실행할 수 있지만, 히트 결과는 항상 +Y가 위쪽이고 중력 방향과 반대인 포즈를 반환합니다. 수평면에서는 히트 테스트가 정확하게 반환됨 훨씬 더 빠르게 위치를 잡을 수 있습니다.

추적 메서드 전환 매끄럽게

실제 깊이를 사용할 수 있게 되면 ARCore는 InstantPlacementPoint의 추적 메서드를 FULL_TRACKING까지 SCREENSPACE_WITH_APPROXIMATE_DISTANCE 점의 포즈도 실제 깊이를 반영하도록 변경됩니다. 이로 인해 객체가 갑자기 커지거나 작아질 수 있습니다. 이러한 갑작스러운 변경을 방지하려면 InstantPlacementPoint 래퍼를 추가합니다.

// Wrapper class to track state to reduce sudden visual changes in object size
class WrappedInstantPlacement {
  public InstantPlacementPoint point;
  public InstantPlacementPoint.TrackingMethod previousTrackingMethod;
  public float previousDistanceToCamera;
  public float scaleFactor = 1.0f;

  public WrappedInstantPlacement(
      InstantPlacementPoint point,
      InstantPlacementPoint.TrackingMethod previousTrackingMethod,
      float previousDistanceToCamera) {
    this.point = point;
    this.previousTrackingMethod = previousTrackingMethod;
    this.previousDistanceToCamera = previousDistanceToCamera;
  }
}

// Wrapper class to track state to reduce sudden visual changes in object size
class WrappedInstantPlacement(
  var point: InstantPlacementPoint,
  var previousTrackingMethod: InstantPlacementPoint.TrackingMethod,
  var previousDistanceToCamera: Float,
  var scaleFactor: Float = 1.0f
)

그런 다음 활동에 다음을 추가합니다.

List<WrappedInstantPlacement> wrappedPoints = new ArrayList<>();

public void onDrawFrame(GL10 gl) {
  Frame frame = session.update();
  Camera camera = frame.getCamera();

  // Place an object on tap.
  if (didUserTap()) {
    // Instant Placement should only be applied if no results are available through hitTest.
    List<HitResult> results = frame.hitTest(tapX, tapY);
    if (results.isEmpty()) {
      // Use the estimated distance from the user's device to the closest
      // available surface, based on expected user interaction and behavior.
      float approximateDistanceMeters = 2.0f;

      // Returns a single result if the hit test was successful.
      results =
          frame.hitTestInstantPlacement(tapX, tapY, approximateDistanceMeters);
      if (!results.isEmpty()) {
        // Instant placement was successful.
        InstantPlacementPoint point = (InstantPlacementPoint) results.get(0).getTrackable();
        wrappedPoints.add(new WrappedInstantPlacement(point, point.getTrackingMethod(),
          distance(camera.getPose(), point.getPose())));
      }
    } else {
      // results contain valid hit tests which can be used directly, so instant placement is not required.
    }
  }

  for (WrappedInstantPlacement wrappedPoint : wrappedPoints) {
    InstantPlacementPoint point = wrappedPoint.point;
    if (point.getTrackingState() == TrackingState.STOPPED) {
      wrappedPoints.remove(wrappedPoint);
      continue;
    }
    if (point.getTrackingState() == TrackingState.PAUSED) {
      continue;
    }

    if (point.getTrackingMethod() == TrackingMethod.SCREENSPACE_WITH_APPROXIMATE_DISTANCE) {
       // Continue to use the estimated depth and pose. Record the distance to
       // the camera for use in the next frame if the transition to full
       // tracking happens.
       wrappedPoint.previousDistanceToCamera = distance(point.getPose(), camera.getPose());
    }
    else if (point.getTrackingMethod() == TrackingMethod.FULL_TRACKING) {
      if (wrappedPoint.previousTrackingMethod == TrackingMethod.SCREENSPACE_WITH_APPROXIMATE_DISTANCE) {
        // Change from the estimated pose to the accurate pose. Adjust the
        // object scale to counteract the apparent change due to pose jump.
        wrappedPoint.scaleFactor = distance(point.getPose(), camera.getPose()) /
            wrappedPoint.previousDistanceToCamera;
        // Apply the scale factor to the model.
        // ...
        wrappedPoint.previousTrackingMethod = TrackingMethod.FULL_TRACKING;
      }
    }
  }
}

float distance(Pose p, Pose q) {
  return Math.sqrt(Math.pow(p.tx() - q.tx(), 2) + Math.pow(p.ty() - q.ty(), 2) + Math.pow(p.tz() - q.tz(), 2));
}

var wrappedPoints = mutableListOf<WrappedInstantPlacement>()

fun onDrawFrame(gl: GL10?) {
  val frame = session.update()
  val camera = frame.camera

  // Place an object on tap.
  if (didUserTap()) {
    // Instant Placement should only be applied if no results are available through hitTest.
    var results = frame.hitTest(tapX, tapY);
    if (results.isEmpty()) {
      // Use the estimated distance from the user's device to the closest
      // available surface, based on expected user interaction and behavior.
      val approximateDistanceMeters = 2.0f;

      // Returns a single result if the hit test was successful.
      results = frame.hitTestInstantPlacement(tapX, tapY, approximateDistanceMeters);
      if (results.isNotEmpty()) {
        // Instant placement was successful.
        val point = results[0].trackable as InstantPlacementPoint
        val wrapped = WrappedInstantPlacement(point, point.trackingMethod, point.pose.distance(camera.pose))
        wrappedPoints.add(wrapped)
      }
    } else {
      // Results contain valid hit tests which can be used directly, so Instant Placement 
      // is not required.
    }
  }

  loop@ for (wrappedPoint in wrappedPoints) {
    val point = wrappedPoint.point
    when {
      point.trackingState == TrackingState.STOPPED -> {
        wrappedPoints.remove(wrappedPoint)
        continue@loop
      }
      point.trackingState == TrackingState.PAUSED -> continue@loop
      point.trackingMethod == TrackingMethod.SCREENSPACE_WITH_APPROXIMATE_DISTANCE -> {
        // Continue to use the estimated depth and pose. Record the distance to
        // the camera for use in the next frame if the transition to full
        // tracking happens.
        wrappedPoint.previousDistanceToCamera = point.pose.distance(camera.pose)
      }
      wrappedPoint.previousTrackingMethod == TrackingMethod.SCREENSPACE_WITH_APPROXIMATE_DISTANCE &&
      point.trackingMethod == TrackingMethod.FULL_TRACKING -> {
        // Change from the estimated pose to the accurate pose. Adjust the
        // object scale to counteract the apparent change due to pose jump.
        wrappedPoint.scaleFactor =
          point.pose.distance(camera.pose) / wrappedPoint.previousDistanceToCamera
        // Apply the scale factor to the model.
        // ...
        wrappedPoint.previousTrackingMethod = TrackingMethod.FULL_TRACKING
      }
    }
  }
}

fun Pose.distance(other: Pose) = sqrt(
  (tx() - other.tx()).pow(2.0f) + (ty() - other.ty()).pow(2.0f) + (tz() - other.tz()).pow(2.0f)
)

객체 배치 후 효율성 향상

객체가 올바르게 배치되면 즉시 배치를 사용 중지하여 CPU 주기와 전력을 절약합니다.

void disableInstantPlacement() {
  Config config = new Config(session);
  config.setInstantPlacementMode(Config.InstantPlacementMode.DISABLED);
  session.configure(config);
}

fun disableInstantPlacement() {
  val config = Config(session)
  // Set the Instant Placement mode.
  config.instantPlacementMode = Config.InstantPlacementMode.DISABLED
  session.configure(config)
}