Currently, Clutter does picking by drawing with Cogl and reading
the pixel that's beneath the given point. Since Cogl has a journal
that records drawing operations, and has optimizations to read a
single pixel from a list of rectangle, it would be expected that
we would hit this fast path and not flush the journal while picking.
However, that's not the case: dithering, clipping with scissors, etc,
can all flush the journal, issuing commands to the GPU and making
picking slow. On NVidia-based systems, this glReadPixels() call is
extremely costly.
Introduce geometric picking, and avoid using the Cogl journal entirely.
Do this by introducing a stack of actors in ClutterStage. This stack
is cached, but for now, don't use the cache as much as possible.
The picking routines are still tied to painting.
When projecting the actor vertexes, do it manually and take the modelview
matrix of the framebuffer into account as well.
CPU usage on an Intel i7-7700, tested with two different GPUs/drivers:
| | Intel | Nvidia |
| ------: | --------: | -----: |
| Moving the mouse: |
| Before | 10% | 10% |
| After | 6% | 6% |
| Moving a window: |
| Before | 23% | 81% |
| After | 19% | 40% |
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/154,
https://gitlab.gnome.org/GNOME/mutter/issues/691
Helps significantly with: https://gitlab.gnome.org/GNOME/mutter/issues/283,
https://gitlab.gnome.org/GNOME/mutter/issues/590,
https://gitlab.gnome.org/GNOME/mutter/issues/700
v2: Fix code style issues
Simplify quadrilateral checks
Remove the 0.5f hack
Differentiate axis-aligned rectangles
https://gitlab.gnome.org/GNOME/mutter/merge_requests/189
A clutter actor might be painted on a stage view with a view scale
other than 1. In this case, to show the content in full resolution, the
actor must use a higher resolution resource (e.g. texture), which will
be down scaled to the stage coordinate space, then scaled up again to
the stage view framebuffer scale.
Use a 'resource-scale' property to save information and notify when it
changes.
The resource scale is the ceiled value of the highest stage view scale a
actor is visible on. The value is ceiled because using a higher
resolution resource consistently results in better output quality. One
reason for this is that rendering is often not perfectly pixel aligned,
meaning even if we load a resource with a suitable size, due to us still
scaling ever so slightly, the quality is affected. Using a higher
resolution resource avoids this problem.
For situations inside clutter where the actual maximum view scale is
needed, a function _clutter_actor_get_real_resource_scale() is provided,
which returns the non-ceiled value.
Make sure we ignore resource scale computation requests during size
requests or allocation while ensure we've proper resource-scale on
pre-paint.
https://bugzilla.gnome.org/show_bug.cgi?id=765011https://gitlab.gnome.org/GNOME/mutter/merge_requests/3
This is an ABI break, hopefully an unimportant one since this signal/vmethod
is barely overridden.
The signal has been added an extra ClutterPaintVolume argument, and has been
given a boolean return value. The recursion to the parents has been taken
out of the default implementation and into the caller, using the returned
boolean parameter to control further propagation.
Passing the ClutterPaintVolume is easier on performance, as we don't need
setting this pointer as gobject data just to retrieve/unset it further
in propagation.
https://bugzilla.gnome.org/show_bug.cgi?id=782344
Mutter (and libmutter users) are the only users of this version of
cogl, and will more or less only use the cogl-1.0, cogl-2.0 and cogl
experimental API variants, and having the possibility of having
different API versions of the same API depending on what file includes
it is error prone and confusing. Lets just remove the possibility of
having different versions of the same API.
https://bugzilla.gnome.org/show_bug.cgi?id=768977