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I'm rendering successfully my OpenGL view by drawing an offscreen texture (which is created by an offscreen framebuffer).

draw -> offscreen FBO/Texture ------> onscreen FBO ---> render buffer -> context

Now I want to reuse offscreen texture to render another OpenGL context.

draw -> offscreen FBO/Texture ----> onscreen FBO ---> render buffer -> context
                             \----> onscreen FBO2---> render buffer2 ->context 2

I tried but can not render anything to context 2. Anyone got this issue, and know how to configure to share texture?

Thanks!

UPDATE: I've just created a simple project describing what I'm doing with Framebuffer and double contexts. http://www.mediafire.com/?vxv1bubzvio4q7h

KONG
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2 Answers2

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You will use EAGLSharegroup. You can read about it on these links.

https://developer.apple.com/library/ios/#qa/qa1612/_index.html

https://developer.apple.com/library/ios/#documentation/OpenGLES/Reference/EAGLSharegroup_ClassRef/Reference/EAGLSharegroup.html

https://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/ConcurrencyandOpenGLES/ConcurrencyandOpenGLES.html

Skyler Saleh
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  • I tried to create context2 which is in same sharegroup of context1, then render context2 with a texture identify which is created in context1. But when context1 still render draw normally, I have no result in context2. Both contexts are in main thread, I bind texture before rendering texture, call glFlush after rendering it in each context. – KONG Mar 31 '11 at 04:37
  • Are you making sure to call [EAGLContext setCurrentContext:context]; before rendering in each context. – Skyler Saleh Mar 31 '11 at 04:41
  • I'm sure about that. What I do is subclass current EAGLView sample from apple, and call setFramebuffer (which includes setContext) before calling texture rendering code. Are there any debug way to make sure that I can access texture1 in context2? – KONG Mar 31 '11 at 05:02
  • hey, I updated my question with a sample project. Can you take a look at it? – KONG Mar 31 '11 at 05:20
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I realise that you are trying to share the textures and I am not, but I offer this answer as your symptom seems to be the same as mine...

In my case, I was also getting an GL_INVALID_VALUE when binding the texture. It turned out that I wasn't switching to the second context prior to creating the textures for it. Thus they were being created in the first context. My render, however WAS switching contexts and therefore failing to find the textures.

Hari Honor
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