This adds cogl_framebuffer_ apis for drawing attributes and primitives
that replace corresponding apis that depend on the default CoglContext.
This is part of the on going effort to adapt the Cogl api so it no
longer depends on a global context variable.
All the new drawing functions also take an explicit pipeline argument
since we are also aiming to avoid being a stateful api like Cairo and
OpenGL. Being stateless makes it easier for orthogonal components to
share access to the GPU. Being stateless should also minimize any
impedance miss-match for those wanting to build higher level stateless
apis on top of Cogl.
Note: none of the legacy, global state options such as
cogl_set_depth_test_enabled(), cogl_set_backface_culling_enabled() or
cogl_program_use() are supported by these new drawing apis and if set
will simply be silently ignored.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
Flushing the clip state no longer does anything that would cause the
journal to flush. The clip state is only flushed when flushing the
framebuffer state and in all cases this ends up flushing the journal
in one way or another anyway. Avoiding flushing the journal will make
it easier to log the clip state in the journal.
Previously when trying to set up a rectangle clip that can't be
scissored or when using a path clip the code would use cogl_rectangle
as part of the process to fill the stencil buffer. This is now changed
to use a new internal _cogl_rectangle_immediate function which
directly uses the vertex array API to draw a triangle strip without
affecting the journal. This should be just as efficient as the
previous journalled code because these places would end up flushing
the journal immediately before and after submitting the single
rectangle anyway and flushing the journal always creates a new vbo so
it would effectively do the same thing.
Similarly there is also a new internal _cogl_clear function that does
not flush the journal.
