CoglOffscreennew_with_texture

This creates an offscreen framebuffer object using the given texture as the primary color buffer. It doesn’t just initialize the contents of the offscreen buffer with the texture; they are tightly bound so that drawing to the offscreen buffer effectively updates the contents of the given texture. You don’t need to destroy the offscreen buffer before you can use the texture again.

This api only works with low-level CoglTexture types such as CoglTexture2D and not with meta-texture types such as CoglTexture2DSliced.

The storage for the framebuffer is actually allocated lazily so this function will never return NULL to indicate a runtime error. This means it is still possible to configure the framebuffer before it is really allocated.

Simple applications without full error handling can simply rely on Cogl to lazily allocate the storage of framebuffers but you should be aware that if Cogl encounters an error (such as running out of GPU memory) then your application will simply abort with an error message. If you need to be able to catch such exceptions at runtime then you can explicitly allocate your framebuffer when you have finished configuring it by calling cogl_framebuffer_allocate() and passing in a GError argument to catch any exceptions.