Pushes the given
gles2_ctx onto a stack associated with
ctx so that the OpenGLES 2.0 api can be used instead of
the Cogl rendering apis to read and write to the specified framebuffers.
Usage of the api available through a
CoglGLES2Vtable is only allowed between push_gles2_context
and pop_gles2_context calls.
If there is a runtime problem with switching over to the given
gles2_ctx then this function will return
false and return an error through throws.
A Framebuffer to access to read operations such as glReadPixels. (must be a
A Framebuffer to access for drawing operations such as glDrawArrays. (must
true if operation was successfull or false otherwise and throws will be updated.