Rendering multiple spheres by taping on a detected plane in ARCore

Question

I am trying to make an application where I can render multiple spheres with on tap on a plane in a certain layout. I want it to be in the shape of a certain molecule, the spheres being the composing atoms. I need every individual sphere to be separate entity (separate node) so I can add OnTouchListeners to them and after it to make bonds between selected spheres. I am a little stuck. Does someone have an idea how can I approach this? I am working in android studio with Java and using ARCore and Sceneform.

Answer 1

You can add renderables and anchors when you detect a tape event, or when the user presses a button.

So long as you know the relative positions that you want to add them, you can set the position for each node you add individually by setting a Pose translation.

See below an example of adding a node 1M in front of the centre point of the preview screen:

            // Place the anchor 1m in front of the camera. 
            Frame frame = arFragment.getArSceneView().getArFrame();
            Session session = arFragment.getArSceneView().getSession();
            Anchor newMarkAnchor = session.createAnchor(
                        frame.getCamera().getPose()
                                .compose(Pose.makeTranslation(0, 0, -1f)) //This will place the anchor 1M in front of the camera
                                .extractTranslation());
            AnchorNode addedAnchorNode = new AnchorNode(newMarkAnchor);
            addedAnchorNode.setRenderable(andyRenderable);

You can add multiple AnchorNodes with different renderables, and apply a different translation for each to position it where you want.

The documentation for Pose.makeTranslation is here: https://developers.google.com/ar/reference/java/com/google/ar/core/Pose#makeTranslation(float,%20float,%20float)

You can check on any touch event to see if any individual renderable has been touched and you can add lines between nodes also - see this repo for an example of detecting a renderable being touched and drawing a line between renderables:

• https://github.com/mickod/LineView

Note the above repository used the older release of Sceneform which has been deprecated, but the same principles still apply.