Can I share a external texture between 2 OpenGL contexts, Android

Question

I'm creating 2 threads. Each thread has its own EGL contexts. One thread is in native, where I will render to a texture, another thread is in Java, in which I want to sample from that texture and render to the screen / to an encoder (doesn't matter). I can't make it work. I've tried generating the texture on either of the threads. What I noticed is the texture Ids are duplicated on both threads (I have other textures that are not meant to be shared).

My question is, is it possible to share a texture between 2 threads (and contexts)?

EDIT: SOLUTION

Thanks to Andon and some Googling, I was able to make it work. I created one context in Java on thread one, and the called eglGetCurrentContext() to get the EGLContext in C++. Later, I created the second context in C++ on the second thread with:

eglCreateContext(mEglDisplay, mEglConfig, sharedContext, contextAttribs);

Where sharedContext is the first context.

Answer 1

Yes, resource sharing between contexts is possible.

The command streams in shared contexts are not synchronized though; if you upload data in one thread and use it in another you have to be extra careful that the upload is actually finished first (glFinish (...) followed by some synchronization construct of your own, like a semaphore, will do).

Now, the million dollar question—do you have any control over the creation of these contexts? That is necessary to do resource sharing in EGL. You only need to create one yourself; if you have the other given to you already, you can use it as your share context when creating the second.