gtk4 & shadertoy
Latest update:
All I wanted was to render a nice shader onto an X11 root window, like
so:
(IRL this doesn't look junky, the GPU renders the background at 60
fps.)
First, I tried to search for a "desktop" shadertoy renderer. No
luck. Then I remembered that a nifty gtk4-demo program included some
shader examples. Aha! What if I extract their custom widget & create
a standalone little app?
Second, I tried to find out how to draw gtk4 widgets onto an X11 root
window. No luck. Apparently, this has been deprecated:
'The root window is an X11-centric concept that is no longer exposed in
the backend-neutral GDK API.'
Third, I attempted to simulate such behavior by having the app send
hints to the WM, such as "I want to be on the lowest layer, on every
virtual desktop, & not listed in the taskbar." Theoretically, this
can be achieved by setting a couple of X11 Atoms for a specific window
in the _NET_WM_STATE list.
The troubles began with the WM I'm using--fvwm3. While I managed to
set the _NET_WM_STATE_BELOW Atom without any server errors using
ancient X11 APIs (XSendEvent), the WM ignored the operation until I
added the following line to ~/.fvwm/config:
Style * EWMHUseStackingOrderHints
But no matter what I did next, fvwm3 refused to obey messages for
_NET_WM_STATE_SKIP_TASKBAR & _NET_WM_STATE_SKIP_PAGER Atoms. I
asked on fvwmforums.org what could be the reason, but received 0
answers.
Then it was gtk4 itself. I suspect that the authors assume you will
develop apps with the full gtk4/glib repositories cloned for
reference, because good tutorials are scant & the APIs docs are devoid
of examples. The most primitive stuff, like parsing command line
options, took me several hours to figure out.
The only pleasant surprise was finding gdk_frame_clock_get_fps() in
the repo. I didn't anticipate such luxury.
The final result is
here. I think I should
incorporate some form of a socket listener into the app, allowing
external programs to send commands such as "change the shader,"
"quit," "pause," &c.
Tags: ойті
Authors: ag