When painting, actors rely on semi global state tracked by the state to
get various things needed for painting, such as the current draw
framebuffer. Having state hidden in such ways can be very deceiving as
it's hard to follow changes spread out, and adding more and more state
that should be tracked during a paint gets annoying as they will not
change in isolation but one by one in their own places. To do this
better, introduce a paint context that is passed along in paint calls
that contains the necessary state needed during painting.
The paint context implements a framebuffer stack just as Cogl works,
which is currently needed for offscreen rendering used by clutter.
The same context is passed around for paint nodes, contents and effects
as well.
In this commit, the context is only introduced, but not used. It aims to
replace the Cogl framebuffer stack, and will allow actors to know what
view it is currently painted on.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
Mutter needs to know which framebuffer the paint nodes will be
drawn into, and using cogl_get_draw_framebuffer() directly is
not an option since ClutterRootNode only pushes the draw fb
at draw time.
Expose clutter_paint_node_get_framebuffer().
https://gitlab.gnome.org/GNOME/mutter/merge_requests/409
The ClutterRootNode paint node is theoretically the
top-most node of a paint nodes tree, except that we
are not in the point of having full rendering trees
in Clutter (all rendering performed by paint nodes
is still local and immediate).
When controlling the rendering tree, MetaShapedTexture
may need to paint into an offscreen framebuffer under
some circumstations.
Expose ClutterRootNode so that MetaShapedTexture can
use it to render to offscreen framebuffers.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/405
When painting to an offscreen framebuffer, MetaShapedTexture will
need to have full control of the painting routines of paint nodes.
As such, expose clutter_paint_node_paint() to allow forcing a
paint nodes paint from MetaShapedTexture.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/405
The multitexture API is not a shortcut for multiple calls
to the single texture API. It is meant to wrap calls to
cogl_framebuffer_draw_multitexture_rectangle(), which
uses the passed texture coordinates at different layers of
the pipeline.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/405
