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holyll
01-17-2013, 10:57 AM
Hi,
I want to compute FFT using opengl and shaders.
I have seen that some people have done this using the fragment shader like this one GPU GEMS 2 (http://http.developer.nvidia.com/GPUGems2/gpugems2_chapter48.html)

But I think of using the Transform FeedBack Buffer. However, it is really difficult to find a simple example of it.
I already have the OpenGl superbible book in which this method is explaned but the example is highly difficult (flocking ).

So I wonder if using the Transform feedback is a good idea and if so do you know some basic tutorials of how to use it?


Thank you.

Dark Photon
01-17-2013, 06:00 PM
For how to use it, check out these links:

* Modern OpenGL (http://github.prideout.net/modern-opengl-prezo/modern-opengl.pdf)
* Tutorial 28 (OGLDev) (http://ogldev.atspace.co.uk/www/tutorial28/tutorial28.html)

As to if it's a good idea, I'm no GPGPU guru, but a brief look at the data flow suggest you probably need some way to do feedback. Could do with transform feedback and vtx shader only, or could do with point fragments scattered to the appropriate places in a destination rendertarget by setting gl_Position. There are probably other way too though. You may want to do a literature search. This kind of thing has been done for 10 years or more using GPUs and it might save you from re-inventing the wheel.