Make A Copy Of A Exist Texture

Hi everyone, how should I make a sub-copy of exist textures ? It seems that the OpenGL does not supply a routine to do this, how should I do this ? Readback or bind to a offscreen buffer, then use glCopySubTexImage ?

Thanks !

You can use one FBO in combination with glTexSubimage like you said, or you can use two FBOs in combination with framebuffer blitting. The latter is a bit more flexible as it allows mirroring/stretching…