ARCore + Unity + Augmented Images - Load different prefabs for different Images

Question

How do I assign different prefabs to different images?

right now, I have all my prefabs loading in on top of each other but how do I get it so each prefab loads in only once on top of one image so each image has a different prefab?

I've modified the sample code (the frame corners) to load in my own prefab and used a dictionary to pair the prefabs with images from the database but when the program runs it instatiates all the prefabs in the same place rather than putting one prefrab on each image it puts all the prefabs on every image - this is the code I've been using:

        public GameObject obj1, obj2, obj3, obj4;
    Dictionary<int, GameObject> imagePrefabPairs;
    public AugmentedImage Image;

    void Start()
    {
        instantiateDictionary();
    }

    // TODO: make initialisation dynamic, to match the size of the db.
    public void instantiateDictionary()
    {
        imagePrefabPairs = new Dictionary<int, GameObject>
        {
            { 0, obj1 },
            { 1, obj2 },
            { 2, obj3 },
            { 3, obj4 }
        };
    }

    public void Update()
    {
        if (Image == null || Image.TrackingState != TrackingState.Tracking)
        {
            obj1.SetActive(false);
            obj2.SetActive(false);
            obj3.SetActive(false);
            obj4.SetActive(false);
            return;
        }
        Pose _centerPose = Image.CenterPose;
        imagePrefabPairs[Image.DatabaseIndex].transform.localPosition = _centerPose.position;
        imagePrefabPairs[Image.DatabaseIndex].transform.localScale = new Vector3(0.1f, 0.1f, 0.1f);
        imagePrefabPairs[Image.DatabaseIndex].SetActive(true);
    }

I figure that I need to have some kind of if statement to ask if one prefab is loaded in and then just choose to load in the next one and have them instantiate one at a time but I am not sure how to do that, or if there is a more direct way to make that happen...?

Answer 1

I assign different prefabs to different images by this way:

• I modified the AugmentedImageExampleController.cs:.
• I added a list for prefabs:

public List<AugmentedImageVisualizer> prefabs = new List<AugmentedImageVisualizer>();

• For the related image for the prefab I did a reference by using the image.DatabaseIndex in the visualizer:

visualizer = (AugmentedImageVisualizer)Instantiate(prefabs[image.DatabaseIndex], anchor.transform);

In the inspector of ExampleController you can put in the prefabs (AugmentedImageVisualizer) now.

That's it, and its working fine!

Answer 2

You could change your AugmentedImageVisualizer prefab, so that at the start all your different objects are inactive (.SetActive(false);) For changing a prefab you can add it to your hierarchy, set all the objects inactive and then apply the changes. After apply you can delete the prefab from your game hierarchy.

Img 1: Add existing prefab to game hierarchy

Img 2: set all the attached objecty to inactive (1) and apply the changes to the prefab (2)

So when you detect a image from your imagedatabase the AugmentedImageVisualizer prefab is attached and only the object with the given index is set to active. Then your code should work.

Because at the start all your objects are inactive you could change this part of your code:

if (Image == null || Image.TrackingState != TrackingState.Tracking)
    {
        obj1.SetActive(false);
        obj2.SetActive(false);
        obj3.SetActive(false);
        obj4.SetActive(false);
        return;
    }

so that you only deactivate the active object:

if (Image.TrackingState != TrackingState.Tracking)
        {
            imagePrefabPairs[Image.DatabaseIndex].SetActive(false);
            return;
        }