First time poster and totally newbie, easy on me please.
I have an rgb texture. I’d like to read in every single row and rearrange it’s texels in y based on a given function. Add them together and get a new texture.
Could you tell me please what functions should I use?
Suggestion: Start with shader programming - GLSL and also read about 2D samplers.
Else if you do not wish to do shader programming, then do what ever operations you wish in a buffer. Then use that buffer data to load as a texture in texture unit with GL_RGB format. Details are covered in chapter related to texture in red book.
More information on your requirements are needed. The given question mentions nothing about showing something on a screen, which means OpenGL is not needed.
I think this is best done outside of OpenGL. Use any programming language you prefer.
Or is it that you want to show the result on screen, with changes every frame?