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147's picture

Initialization of OpenGL without Window

Posted Sunday, 11 November, 2012 - 17:54 by 147 in

I hope I make no mistake in asking this question, if please say and I will remember it for the future.
I want to use OpenGL for image processing and computer vision, and therefore I use OpenTK.
The problem I have, is that I have to create a Context, but I have no windows?
How can I initialize a context without having a window?

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lid6j86's picture

Re: Initialization of OpenGL without Window

Posted Tuesday, 13 November, 2012 - 19:54 by lid6j86

I'm not sure I understand what you are looking to do

golkeeper's picture

Re: Initialization of OpenGL without Window

Posted Wednesday, 14 November, 2012 - 14:19 by golkeeper

Theoretically, there is one way: http://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_surfaceless_c...

Practically, it is only available under Linux with Mesa drivers, since IHVs rarely bother themselves with implementing EGL in their drivers, not to mention EGL extensions.
It will be easier to make hidden window of any kind to workaround this, or destroy window right after context creation.

147's picture

Re: Initialization of OpenGL without Window

Posted Wednesday, 14 November, 2012 - 15:52 by 147

@ lid6j86 I want to use OpenGL for a Image processing library and I think from the Point of programming a class library shouldn't create a window.
Perhaps it is a Little bit of Topic, but would OpenCL be a good alternative? Can I send a Picture to the GPU with OpenCL and process it?

golkeeper's picture

Re: Initialization of OpenGL without Window

Posted Friday, 16 November, 2012 - 15:12 by golkeeper

Yes you can. But I'd suggest you to take a look at opengl 4.3 compute shaders, it's simpler and suited exactly to solve image processing tasks.

147's picture

Re: Initialization of OpenGL without Window

Posted Friday, 16 November, 2012 - 17:43 by 147

Can ComputeShaders be used without initialization of a device? And are ComputeShaders allready implemented in OpenTK, and is there a Little good tutorial about them?
And a question which may also interesting.
Is it possible to Transfer a Image to the GPU with OpenCL so that it can be used by DirectX or OpenGL?

golkeeper's picture

Re: Initialization of OpenGL without Window

Posted Monday, 19 November, 2012 - 07:56 by golkeeper
Quote:

Can ComputeShaders be used without initialization of a device?

No, you still need window to get OpenGL context.

Quote:

And are ComputeShaders allready implemented in OpenTK, and is there a Little good tutorial about them?

Probably not, AFAIK OpenTK does not support OpenGL4.3.

Quote:

Is it possible to Transfer a Image to the GPU with OpenCL so that it can be used by DirectX or OpenGL?

You can share resources (incl images stored in GPU memory) between OpenCL and OpenGL. If your IHV is Nvidia, you may read/write DirectX resources from OpenGL via their DirectX interop OpenGL extension.