GLX backend sometimes tramples on wallpaper

[sersorrel]

Platform: Ubuntu Desktop 18.04 amd64

GPU, drivers, and screen setup: Intel i7-8750H integrated graphics, modesetting driver (Ubuntu kernel 4.15.0-45), two monitors configured vertically (external above, laptop monitor below) with xrandr, window manager is i3

Compton version: 0.1~beta2+20150922 from Ubuntu repos

Compton configuration: /dev/null

Steps of reproduction

$ compton --config /dev/null --backend=glx

Expected behavior

Compton should not affect my wallpaper (set with feh --bg-fill).

Current Behavior & Other details

When I run compton, it changes the wallpaper on my internal monitor to a series of vertical black/white/grey lines, looking something like this (cropped from a photo, it's not actually tilted):

My external monitor still has the normal wallpaper, and stopping compton restores the normal wallpaper.

If I run feh again at any point, then the wallpaper is fine even if I stop and restart compton.

(Using the xrender backend, I get the Windows XP solitaire effect where dragging a window around over the wallpaper doesn't redraw the wallpaper where the window was, unless I have run feh again, in which case it behaves normally – so maybe it is not an issue with the GLX backend specifically?)

[sersorrel]

It now looks like this:

I suspect it's the bottom edge (or somewhere near the bottom edge) of my wallpaper.

[sersorrel]

Aha, it is the bottom edge (thanks to GIMP for the eye-mangling gradient):

[yshui]

Can you try if the current development version of compton (https://github.com/yshui/compton) fix your problem?

If not, can you report the issue in the development repo? Thanks.

[sersorrel]

@yshui thanks, I tested on your version and the issue is still there, so I opened an issue.

The xrender backend works fine on your version, though – if I knew how to compile in DRM vsync support, that might be good enough for me.