Remove Darkening Around Kawase'd Windows

[ghost]

Platform

Arch Linux

GPU, drivers, and screen setup

Intel Graphics, xf86-video-intel

name of display: :0
display: :0  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: Intel Open Source Technology Center (0x8086)
    Device: Mesa DRI Intel(R) Ivybridge Mobile  (0x166)
    Version: 19.3.2
    Accelerated: yes
    Video memory: 1536MB
    Unified memory: yes
    Preferred profile: core (0x1)
    Max core profile version: 4.2
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.0
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile 
OpenGL core profile version string: 4.2 (Core Profile) Mesa 19.3.2
OpenGL core profile shading language version string: 4.20
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 3.0 Mesa 19.3.2
OpenGL shading language version string: 1.30
OpenGL context flags: (none)

OpenGL ES profile version string: OpenGL ES 3.0 Mesa 19.3.2
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

Environment

Awesome Window Manager

picom version

picom feature/dual_kawase vgit-f92eb

Configuration:

# Shadow
shadow = false;
shadow-radius = 7;
shadow-offset-x = -7;
shadow-offset-y = -7;
log-level = "warn";
# log-file = "/path/to/your/log/file";
shadow-opacity = 0.0;
# shadow-red = 0.0;
# shadow-green = 0.0;
# shadow-blue = 0.0;
shadow-exclude = [
	"name = 'Notification'",
	"class_g = 'Conky'",
	"class_g ?= 'Notify-osd'",
	"class_g = 'Cairo-clock'",
	"_GTK_FRAME_EXTENTS@:c"
];
# shadow-exclude = "n:e:Notification";
# shadow-exclude-reg = "x10+0+0";
# xinerama-shadow-crop = true;

# Opacity
# inactive-opacity = 0.8;
# active-opacity = 0.8;
# frame-opacity = 0.7;
# inactive-opacity-override = false;
# inactive-dim = 0.2;
# inactive-dim-fixed = true;

blur: {
  method = "dual_kawase";
  strength = 2.0;
  # deviation = 1.0;
  # kernel = "11x11gaussian";
}

# blur-background = true;
# blur-background-frame = true;
blur-kern = "3x3box";
# blur-kern = "5,5,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1";
# blur-background-fixed = true;
blur-background-exclude = [
	"window_type = 'dock'",
	"window_type = 'desktop'",
	"_GTK_FRAME_EXTENTS@:c"
];
# opacity-rule = [ "80:class_g = 'URxvt'" ];

# max-brightness = 0.66

# Fading
fading = true;
# fade-delta = 30;
fade-in-step = 0.03;
fade-out-step = 0.03;
# no-fading-openclose = true;
# no-fading-destroyed-argb = true;
fade-exclude = [ ];

# Other
backend = "glx";
mark-wmwin-focused = true;
mark-ovredir-focused = true;
# use-ewmh-active-win = true;
detect-rounded-corners = true;
detect-client-opacity = true;
refresh-rate = 0;
vsync = true;
# sw-opti = true;
# unredir-if-possible = true;
# unredir-if-possible-delay = 5000;
# unredir-if-possible-exclude = [ ];
focus-exclude = [ "class_g = 'Cairo-clock'" ];
detect-transient = true;
detect-client-leader = true;
invert-color-include = [ ];
# resize-damage = 1;

# GLX backend
# glx-no-stencil = true;
# glx-no-rebind-pixmap = true;
# xrender-sync-fence = true;
use-damage = true;

# Window type settings
wintypes:
{
  tooltip = { fade = true; shadow = false; opacity = 0.75; focus = true; full-shadow = false; };
  dock = { shadow = false; }
  dnd = { shadow = false; }
  popup_menu = { opacity = 0.8; }
  dropdown_menu = { opacity = 0.8; }
};

Steps of reproduction

1. Enable the blur using the blur:{ .. } just like in my config above.
2. Add opacity effect to terminals.
3. Remove gaps or move two blurred transparent window next to each other

Expected behavior

There's should be no darkening between the blurred windows

Current Behavior

There are some darkening around the blurred terminals

Other details

If I set the blur method to none, the dark borders disappeared. But even setting the blur strength to 0.0, it still appears.
Earlier, I found out that the shadow-like effect shows when if there is --experimental-backends

With that being said, my question is: Is there a way to disable this effect?
Launching picom by:

picom -b --experimental-backends --dbus --config picom.conf 

[tryone144]

Hi, this is most likely the same effect you described here: yshui/picom#298

The blur-kernel is applied sequentially for each window and the shadow-like effect is actually the partially blurred borders of the adjacent windows. A few pixels around the real window border are taken into account to prevent some clipping-artificats.

You may try out the experimental --transparent-clipping option mentioned here yshui/picom#265 (comment) which disregards all windows and just blurs the wallpaper.

[ghost]

Oh, I see. Thanks for the explanation. I posted here again because I thought using the dual_kawase method we can disable that. Thanks again!!

You may try out the experimental --transparent-clipping option mentioned here yshui#265 (comment) which disregards all windows and just blurs the wallpaper.

Actually I already tried it but the shadow-like effect was still there. Anyway, thank you for bringing your kawase method to picom!