What's the state of Open Source softwares for AR/VR?

[arthurgretta]

I know good alternatives will come up eventually, but how far away are we? Are there any good Open Source frameworks to rival ARCore, ARKit and Vuforia under development? How far away are we in getting Open source AR frameworks with 6DoF positional tracking ?

Because I don't trust these proprietary software like vuforia and it's paid but it's the only option which is cross platform.