Shaders: uniform for window resolution, not just split resolution

[adamchalmers]

Seems all the shaders run per-split, not per-window. This means if you use multiple splits, each shader has its own little resolution, e.g.

I think this is because iResolution uniform gives the resolution of the split, not the window.

I would love for the entire window to be shaded the same, e.g. for the gradient to stretch across the entire window, not across each individual split. Is there any way for shaders to access the resolution of the entire window? If not, perhaps the window resolution should be a uniform exposed just like iResolution is.

[rhodes-b]

im not sure this is even possible as each split is its own opengl context (just like tabs and separate windows)

if it is it would require a complete redo on how ghostty renders as you need to share information to all current "realized" surfaces (a surface is a generic term for what renders in a window/tab/split)

[adamchalmers]

If the individual surfaces could somehow access the total window dimensions, and their position within that window, that would suffice for the shader I'd like.

[mitchellh]

I'm supportive of this, but I don't think we even have access to this information in Ghostty core at the moment. So I'll have to think about how we represent and plumb this through.

[qwerasd205]

Ideally we can have the apprt provide the window-relative coordinates of each split, then do some fiddling in the renderer so that the shader thinks it's rendering just the relative range of coordinates. Then we could provide a config option to toggle this behavior of "window-relative shader coordinates"

[jnns]

Especially for a shader implementing a cursor trail it would be nice to be able to follow the cursor more easily when switching focus between splits.