如何在不点击屏幕的情况下放置对象

Question

我正在尝试使用 ARCore 在不点击屏幕的情况下显示对象。 Google提供的ARCore Sceneform基础示例中，检测到表面后需要点击屏幕

我想实现它，AR 无需点击屏幕即可显示对象。

Anchor newAnchor;

    for (Plane plane : mSession.getAllTrackables(Plane.class)) {
        if (plane.getType() == Plane.Type.HORIZONTAL_UPWARD_FACING
                && plane.getTrackingState() == TrackingState.TRACKING)
        {
            newAnchor = plane.createAnchor(plane.getCenterPose());
            break;
        }
    }

我试过不用点击屏幕就可以显示。

如果有人知道如何做到这一点，请帮助我。提前致谢

Answer 1

虽然我建议您在用户点击时放置对象以及 s/he 在屏幕上点击的位置，但您的要求可以像这样实现。（这个例子是在 Kotlin 中）

在开始放置对象之前，您需要创建一个 ModelRenderable。全局声明一个@Nullable。

private var modelRenderable: ModelRenderable? = null

//Create the football renderable
ModelRenderable.builder()
                //get the context of the ARFragment and pass the name of your .sfb file
                .setSource(fragment.context, Uri.parse("FootBall.sfb"))
                .build()

                //I accepted the CompletableFuture using Async since I created my model on creation of the activity. You could simply use .thenAccept too.
                //Use the returned modelRenderable and save it to a global variable of the same name
                .thenAcceptAsync { modelRenderable -> this@MainActivity.modelRenderable = modelRenderable }

编程的主要部分必须在框架的 onUpdate 方法上完成。所以你像这样为帧更新附加一个监听器

 fragment.arSceneView.scene.addOnUpdateListener(this@MainActivity) //You can do this anywhere. I do it on activity creation post inflating the fragment

现在您可以处理在侦听器上添加对象。

 override fun onUpdate(frameTime: FrameTime?) {
    //get the frame from the scene for shorthand
    val frame = fragment.arSceneView.arFrame
    if (frame != null) {
        //get the trackables to ensure planes are detected
        val var3 = frame.getUpdatedTrackables(Plane::class.java).iterator()
        while(var3.hasNext()) {
            val plane = var3.next() as Plane

            //If a plane has been detected & is being tracked by ARCore
            if (plane.trackingState == TrackingState.TRACKING) {

                //Hide the plane discovery helper animation
                fragment.planeDiscoveryController.hide()


                //Get all added anchors to the frame
                val iterableAnchor = frame.updatedAnchors.iterator()

                //place the first object only if no previous anchors were added
                if(!iterableAnchor.hasNext()) {
                    //Perform a hit test at the center of the screen to place an object without tapping
                    val hitTest = frame.hitTest(frame.screenCenter().x, frame.screenCenter().y)

                    //iterate through all hits
                    val hitTestIterator = hitTest.iterator()
                    while(hitTestIterator.hasNext()) {
                        val hitResult = hitTestIterator.next()

                        //Create an anchor at the plane hit
                        val modelAnchor = plane.createAnchor(hitResult.hitPose)

                        //Attach a node to this anchor with the scene as the parent
                        val anchorNode = AnchorNode(modelAnchor)
                        anchorNode.setParent(fragment.arSceneView.scene)

                        //create a new TranformableNode that will carry our object
                        val transformableNode = TransformableNode(fragment.transformationSystem)
                        transformableNode.setParent(anchorNode)
                        transformableNode.renderable = this@MainActivity.modelRenderable

                        //Alter the real world position to ensure object renders on the table top. Not somewhere inside.
                        transformableNode.worldPosition = Vector3(modelAnchor.pose.tx(),
                                modelAnchor.pose.compose(Pose.makeTranslation(0f, 0.05f, 0f)).ty(),
                                modelAnchor.pose.tz())
                    }
                }
            }
        }
    }
}

我使用了一种扩展方法

//A method to find the screen center. This is used while placing objects in the scene
private fun Frame.screenCenter(): Vector3 {
    val vw = findViewById<View>(android.R.id.content)
    return Vector3(vw.width / 2f, vw.height / 2f, 0f)
}

这是最终结果

Answer 2

如果您不想使用 hit-testing 或 button's action 方法在真实环境中放置对象，您可以使用例如相机的 Pose 进行自动放置（记住，你必须在ARCamera前面添加一个ARAnchor，它对应的Node和一个Renderable，即沿着-Z方向）：

if (this.anchorNode == null) {

    Session session = arFragment.getArSceneView().getSession();

    float[] position = { 0, 0, -0.75 };       // 75 cm away from camera
    float[] rotation = { 0, 0, 0, 1 };

    Anchor anchor =  session.createAnchor(new Pose(position, rotation));

    anchorNode = new AnchorNode(anchor);
    anchorNode.setRenderable(yourModelRenderable);
    anchorNode.setParent(arFragment.getArSceneView().getScene());
}

希望对您有所帮助。

Answer 3

如果你只想放置一个对象，这里是代码片段。谢谢@clinkz

override fun onUpdate(frameTime: FrameTime?) {
    arFragment?.let { fragment ->
        fragment.arSceneView?.let { sceneView ->
            sceneView.arFrame?.let { frame ->
                if (!placed) {
                    val trackable = frame.getUpdatedTrackables(Plane::class.java).iterator()
                    if (trackable.hasNext()) {
                        val plane = trackable.next() as Plane
                        if (plane.trackingState == TrackingState.TRACKING) {
                            fragment.planeDiscoveryController?.hide()
                            val hitTest =
                                frame.hitTest(frame.screenCenter().x, frame.screenCenter().y)
                            val hitTestIterator = hitTest.iterator()
                            if (hitTestIterator.hasNext()) {
                                val hitResult = hitTestIterator.next()
                                val modelAnchor = plane.createAnchor(hitResult.hitPose)
                                val anchorNode = AnchorNode(modelAnchor)
                                anchorNode.setParent(sceneView.scene)

                                val transformableNode =
                                    TransformableNode(fragment.transformationSystem)
                                transformableNode.setParent(anchorNode)
                                transformableNode.renderable = this@ARActivity.modelRenderable

                                transformableNode.worldPosition = Vector3(
                                    modelAnchor.pose.tx(),
                                    modelAnchor.pose.compose(
                                        Pose.makeTranslation(
                                            0f,
                                            0.05f,
                                            0f
                                        )
                                    ).ty(),
                                    modelAnchor.pose.tz()
                                )
                                placed = true
                            }
                        }
                    }
                }
            }
        }
    }
}

private fun Frame.screenCenter(): Vector3 {
    val vw = findViewById<View>(android.R.id.content)
    return Vector3(vw.width / 2f, vw.height / 2f, 0f)
}

如何在不点击屏幕的情况下放置对象

How to place a object without tapping on the screen

android

arcore