I'm new here.Thanks for your help! I want to create two windows to draw the same picture. I hope to use the same texture to draw the picture in the two windows so that it's unnecessary to copy the pixels from the framebuffer and then copy them into another texture. I need do this step every frame so it cost lots of time. I'm puzzled that since the texture datas have already existed in the memory of GPU, why not using them in different windows? Or are there some other functions or method to realize? Looking forward for answers.Thank you very much!

On Win32, you can take a look at wglShareLists. This function was ment for display lists, but works for all OpenGL objects, as textures.