If we modify the paint volume to make it larger and include the blur
radius, we should also use the gained size and draw something there.
Since the framebuffers are only the size of the actor to blur, we're not
doing that right now anyway, so remove the vfunc override.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/991
Use the shader for linear sampling and incremental calculation of the
gaussian kernel values as it was implemented by Patrick Walton in
webrender.
The sigma value for the blur (the standard deviation) is calculated by
taking the blur radius and dividing it by 3, this value is used by most
implementations of gaussian blurs since it covers a high percentage of
the gaussian shape.
The linear sampling optimization is implemented by skipping every second
texel (i += 2) in the for-loop that's sampling adjacent texels.
https://github.com/servo/webrender/blob/master/webrender/res/cs_blur.glsl38ec7db6f1https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/991
Floor the downscaled size of the new framebuffer to make sure we don't
initialize a framebuffer with a floating point value that might be
interpreted wrong by `cogl_texture_2d_new_with_size` and end up with a
slightly wrong aspect ratio of the framebuffer.
This fixes situations where the widths or heights of downscaled
framebuffers sometimes miss some pixels at the border.
While at it, remove the `downscale_factor` argument from
`setup_projection_matrix` since that function doesn't need the initial
size of the actor anyway.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/991
The brightness property of ShellBlurEffect is of float type, but
we are calling g_value_set_int() in the GObject::get_property()
handler, which throws warnings when trying to set the property
via g_object_set() and family.
Use g_value_set_float() instead.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/924
This is a moderately fast two-pass gaussian blur implementation.
It downscales the framebuffer dynamically before applying the
gaussian shader, which cuts down rendering time quite considerably.
The blur shader takes 2 uniforms as input: the blur radius; and
whether to blur vertically or horizontally.
The blur radius is treated as an integer in C land to simplify
calculations. The vertical parameter is treated as an integer by
the shader simply due to Cogl not having proper boolean support
in snippets.
At last, brightness is also added to avoid needing to use an extra
effect to achieve that. Brightness is applied in a different pipeline
than blur, so we can control it more tightly.
ShellBlurEffect also implements a "background" mode, where the contents
beneath the actor are blurred, but not the actor itself. This mode is
performance-heavy.
Related: https://gitlab.gnome.org/GNOME/gnome-shell/issues/1848https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/864
