앱에서 Instant Placement API를 사용하는 방법을 알아봅니다.
기본 요건
계속 진행하기 전에 기본 AR 개념과 ARCore 세션 구성 방법을 이해해야 합니다.
인스턴트 게재위치를 사용하여 새 세션 구성
새 ARCore 세션에서 인스턴트 게재위치 모드를 사용 설정합니다.
Java
// 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);
}
Kotlin
// 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()
를 사용하여 화면 탭 위치가 지정된 추적 가능한 인스턴트 게재위치 포인트를 만듭니다.
getPose()
메서드로 현재 포즈를 가져옵니다.
Java
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();
}
}
}
Kotlin
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 게재위치는 대략적인 거리로 화면 공간 추적을 지원하며 인스턴트 게재위치 포인트가 실제 세계에 고정되면 자동으로 전체 추적으로 전환됩니다. getPose()
를 사용하여 현재 포즈를 가져옵니다.
getTrackingMethod()
를 사용하여 현재 추적 메서드를 가져옵니다.
ARCore는 모든 방향의 표면에서 인스턴트 게재위치 히트 테스트를 실행할 수 있지만 히트 결과에서는 항상 중력 방향을 기준으로 +Y가 위로 향하는 포즈를 반환합니다. 가로 표면에서는 히트 테스트가 정확한 위치를 훨씬 더 빠르게 반환합니다.
원활한 추적 방법 전환
실제 깊이를 사용할 수 있게 되면 ARCore는 InstantPlacementPoint
의 추적 메서드를 SCREENSPACE_WITH_APPROXIMATE_DISTANCE
에서 FULL_TRACKING
로 변경합니다.
점의 포즈도 실제 깊이를 반영하도록 변경됩니다.
이로 인해 객체가 갑자기 커지거나 축소되는 것처럼 보일 수 있습니다.
이 갑작스러운 변경을 방지하려면 InstantPlacementPoint
래퍼를 추가합니다.
Java
// 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;
}
}
Kotlin
// 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.
Java
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));
}
Kotlin
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
CPU 주기 및 전원을 절약하기 위해 객체가 올바르게 배치된 경우 인스턴트 게재위치를 사용 중지합니다.
Java
void disableInstantPlacement() {
Config config = new Config(session);
config.setInstantPlacementMode(Config.InstantPlacementMode.DISABLED);
session.configure(config);
}
Kotlin
fun disableInstantPlacement() {
val config = Config(session)
// Set the Instant Placement mode.
config.instantPlacementMode = Config.InstantPlacementMode.DISABLED
session.configure(config)
}