Proposal: user-defined shaders

[ddevault]

Not sure if we actually want to do this, but someone on HN proposed it and it might not be that rough after I gave it some thought.

shader my-shader load path/to/vertex.glsl path/to/fragment.glsl
shader my-shader set my_color vec3 0.0 0.0 1.0 1.0
for_window [.*] shader my-shader

We'd then use these shaders when rendering those windows, rather than the wlr_renderer shaders. Seeking feedback.

[ddevault]

Hmm, annoying problem: different pixel formats.

[rkanati]

How would this interact with, e.g. the vulkan renderer proposal? And how much could you really achieve with this - cute effects, sure, but is there something bigger I'm missing?

[ddevault]

Just cute effects, yeah. Not sure how it would interact with the Vulkan proposal (poorly, I assume).

[edrex]

Practical use case: one could use this to implement a generic "dark mode" that value-inverts pixels if the average pixel value over the window is > 50% (like FF Dark Reader addon, thanks @ShinyRice)

[cafehaine]

I guess it also could be used to implement the rounded corners that some users were asking for

[mxmilkiib]

Also to tint icons of applications/etc in a bar/panel to match the general colour theme. There is X11 bar/panel that does that, cannot remember the name though (was it tint2?).

[emersion]

Practical use case: one could use this to implement a generic "dark mode" that value-inverts pixels

Yes

if the average pixel value over the window is > 50%

Probably not.

I guess it also could be used to implement the rounded corners that some users were asking for

No

Also to tint icons of applications/etc in a bar/panel to match the general colour theme.

And no

[ddevault]

Wait, why couldn't user-defined shaders be used to implement rounded corners? And tinting icons in the bar seems possible to me too. "Average pixel value" does sound difficult-to-impossible though.

[emersion]

Wait, why couldn't user-defined shaders be used to implement rounded corners?

We render them as rectangles separately from the window. We'd need to change how we render borders and titlebars. Well I guess it would be possible (but more work).

And tinting icons in the bar seems possible to me too

You can't tell whether a pixel is from an icon or not. Or do you want to apply the filter to all pixels no matter what?

[ddevault]

Ah, I was thinking about rounding the actual surface of the window.

You can't tell whether a pixel is from an icon or not. Or do you want to apply the filter to all pixels no matter what?

Just apply the shader to a specific part of the image, and skip that pixel if it's equal to your bar's background color?

[emersion]

Just apply the shader to a specific part of the image, and skip that pixel if it's equal to your bar's background color?

I mean, it could work in some situations, but not if the bar status blocks don't have a fixed width. If you try to apply the filter to the whole bar, it'll break status blocks colors (that match the color scheme). If you have a fixed list of accepted colors, antialiasing is tricky.

[mxmilkiib]

Shaders for patterns on borders? I changed recently from themed border and split indicator colours to try #00ff00 and #ff0000, as I found myself not figuring from peripheral vision where the split was and getting mildly distracted by having to saccade enough to find it. If there were a cycling colour, or slowly moving semi-transparent pattern, or a subtle but steady modulation in glow or occasional gleam in the border on the indicator edge border, even at 2px wide, heck, I could set my active window and split indicator border colours the same and I could (in many possible cases) still/always know whether to open a window or change the split direction. Movement of light and dark can jump out so much more than a static difference in colour. Accessibility and theming. (Eventually, HiDPI Quake water borders..?)

I guess not for sway, but shaders for 'live' virtual desktops? Like Enlightenment (new and old)?

[retrotails]

I'd like to see a full-screen shader option for more advanced redshift alternatives (tinted monochrome, or hue changes so blue != black etc), or maybe more crazy stuff like a reverse-sharpen filter I wrote to work around my TV's always-on filtering. there could be other interesting uses (for the per-window shader) like a chroma key to add transparency to apps that don't support it, so I can see my background for once. (quick and ugly mockup)

oh also idk if windows are repainted every frame or how that works, but a boolean for whether the shader needs updated every frame would be nice.

[emersion]

chroma key to add transparency to apps that don't support it, so I can see my background for once

There's an opacity command.