Using Unity player/engine to load 3d in existing Android application

Have created a Augment Reality app using Vuforia which would play video on recognition. Now, just need the ability to show 3D objects as well. I did follow the video tutorial from Vuforia on this and able to get the 3D models showing on targets using Unity engine. But, when I exported the project as android (eclipse) project I could locate only 3 activity classes. The challenge here is how to integrate these two projects together.

The component that loads 3D model using unity player is abstracted and not exposed. I was thinking I could just simply use the unity player API to load the 3D models within my existing project.

Is there a way the 3D model loading code be exposed to the Java (android) part? As I need to dynamically load the models and might need to download it from the server and load it.

Since we have done so much work on the UI part of our existing application it will be really helpful if we can just plug the Unity player and manage the model inside our app.

Thanks in advance.

Ok, I have made some progress. As a POC I created a simple android application and after some struggles I’m able to bring in the Unity player inside the android app.

I’m able to trigger a method on Unity C# from android which would download and load the model on the empty GameObject. Now here is my question

Currently the Unity player has a solid background (Main Camera from Unity). How do I make this background transparent so that I could show the 3D object on the surface/camera view in the android app?