Pfthb

I develop an android application with ArCore library. I need make two points, draw a line between they and set a text labels near each line.

The text labels need to be rotated face-to-camera and have positions along the line.

1) Add a line between 2 points:

AnchorNode previousPoint = /* point 0 */
AnchorNode currentPoint = /* point 1 */

Vector3 previousPosition = previousPoint.getWorldPosition();
Vector3 currentPosition = currentPoint.getWorldPosition();

Quaternion rotation = currentPoint.getWorldRotation();

float f1 = new floatcurrentPosition.x, currentPosition.y, currentPosition.z;
float f2 = new floatrotation.x, rotation.y, rotation.z, rotation.w;

Vector3 difference = Vector3.subtract(previousPosition, currentPosition);
Vector3 directionFromTopToBottom = difference.normalized();
Quaternion rotationFromAToB = Quaternion.lookRotation(directionFromTopToBottom, Vector3.up());

ModelRenderable model = ShapeFactory.makeCube(new Vector3(.0025f, .0025f, difference.length()), Vector3.zero(), /* material */ );

Anchor anchor = getSession().createAnchor(new Pose(f1, f2));

AnchorNode anchorNode = new AnchorNode(anchor);
anchorNode.setParent(getScene());

Vector3 lineCenter = Vector3.add(previousPosition, currentPosition).scaled(.5f);
Node lineNode = new Node();
lineNode.setParent(anchorNode);
lineNode.setRenderable(model);
lineNode.setWorldPosition(lineCenter);
lineNode.setWorldRotation(rotationFromAToB);

2. Add a text label

 Quaternion cameraRotation = getCamera().getWorldRotation();

 float distance = Vector3.subtract(cameraPosition, lineCenter).length();

 String result = String.format(Locale.ENGLISH, "%.3f", difference.length()) + ".m";

 ViewRenderable textRenderable = mArModelCreator.getTextView();
 ((TextView)textRenderable.getView()
 .findViewById(R.id.textLabel)).setText(result);

 Node textNode = new Node(); 
 textNode.setParent(lineNode);
 textNode.setRenderable(textRenderable); 
 textNode.setWorldScale(new Vector3(1f, 1f, 1f).scaled(distance));
 textNode.setWorldRotation(Quaternion.multiply(rotationFromAToB, cameraRotation));

But I do not have correct result.

My current labels:

What I need:

Please help me.

For resolving the issue I have make a line between vectors by cylinder.

private void addLineBetweenPoints(Scene scene, Vector3 from, Vector3 to) 
 // prepare an anchor position
 Quaternion camQ = scene.getCamera().getWorldRotation();
 float f1 = new floatto.x, to.y, to.z;
 float f2 = new floatcamQ.x, camQ.y, camQ.z, camQ.w;
 Pose anchorPose = new Pose(f1, f2);

 // make an ARCore Anchor
 Anchor anchor = mCallback.getSession().createAnchor(anchorPose);
 // Node that is automatically positioned in world space based on the ARCore Anchor.
 AnchorNode anchorNode = new AnchorNode(anchor);
 anchorNode.setParent(scene);

 // Compute a line's length
 float lineLength = Vector3.subtract(from, to).length();

 // Prepare a color
 Color colorOrange = new Color(android.graphics.Color.parseColor("#ffa71c"));

 // 1. make a material by the color
 MaterialFactory.makeOpaqueWithColor(getContext(), colorOrange)
 .thenAccept(material -> 
 // 2. make a model by the material
 ModelRenderable model = ShapeFactory.makeCylinder(0.0025f, lineLength,
 new Vector3(0f, lineLength / 2, 0f), material);
 model.setShadowReceiver(false);
 model.setShadowCaster(false);

 // 3. make node
 Node node = new Node();
 node.setRenderable(model);
 node.setParent(anchorNode);

 // 4. set rotation
 final Vector3 difference = Vector3.subtract(to, from);
 final Vector3 directionFromTopToBottom = difference.normalized();
 final Quaternion rotationFromAToB =
 Quaternion.lookRotation(directionFromTopToBottom, Vector3.up());
 node.setWorldRotation(Quaternion.multiply(rotationFromAToB,
 Quaternion.axisAngle(new Vector3(1.0f, 0.0f, 0.0f), 90)));
 );
 

and add a TextNode:

public ViewRenderable getTextView() 
 // return current and make new;
 ViewRenderable renderable = mTextView.makeCopy();
 makeTextModel();
 return renderable;
 

private void makeTextModel() 
 ViewRenderable.builder()
 .setView(LvgApplication.getContext(), R.layout.view_ar_text)
 .build()
 .thenAccept(renderable -> 
 renderable.setShadowCaster(false);
 renderable.setShadowReceiver(false);
 DpToMetersViewSizer viewSizer = new DpToMetersViewSizer(500);
 renderable.setSizer(viewSizer);
 renderable.setHorizontalAlignment(ViewRenderable.HorizontalAlignment.CENTER);
 renderable.setVerticalAlignment(ViewRenderable.VerticalAlignment.CENTER);
 mTextView = renderable;
 );
 

private void addTextNodeToLine(Node node, float length) 
 // make model
 String result = String.format(Locale.ENGLISH, "%.3f", length) + ".m";
 ViewRenderable textRenderable = mArModelCreator.getTextView();
 ((TextView) textRenderable.getView().findViewById(R.id.textLabel)).setText(result);

 Node textNode = new Node();
 textNode.setParent(node);
 textNode.setRenderable(textRenderable);
 textNode.setWorldScale(new Vector3(1f, 1f, 1f).scaled(0));

 textNode.setLocalPosition(new Vector3(
 /* x - width from parent (left/right) */ -0.025f,
 /* y - depth from parent (forward/back) */ length / 2,
 /* z - height from parent (top/down) */ -0.002f));

 Quaternion alongLine = Quaternion.axisAngle(new Vector3(0.0f, 0.0f, 1.0f), -90);
 textNode.setLocalRotation(alongLine);