Liquid (Gl)ass

This tweak is incomplete, issues WILL happen.

Applied to

• folders on the homescreen
• opened folders
• widgets
• underneath app icons
• dock
• lockscreen platter views (notifications & music player)
• quick actions buttons
• app library
• settings app
• clock

Quick explanation on how this tweak works

• the tweak injects a LiquidGlassView into specific springboard surfaces, then feeds that view a backdrop source plus screenspace origin data
• most surfaces are still snapshot / wallpaper based:
  • homescreen, dock, folders, widgets, context menus, App Library, lockscreen platters, etc usually sample from cached wallpaper or cached composite snapshots
  • on iOS 15 and lower it can still decode cpbitmap wallpapers directly
• once a source image is captured, the tweak usually does not rebuild it every frame. the common path is:
  • cache the source image
  • upload it to Metal
  • keep the glass aligned by updating origin / sampling coordinates on display link ticks
  • except for the notification banners which uses a springboard-local live backdrop capture path
• the code splits to these folders:
  • Runtime/ owns the Metal renderer
  • Shared/ owns prefs / logging / hook helpers
  • Hooks/ owns the per-surface injection logic

The Metal shader

• the renderer uploads the source image as a Metal texture, bakes a blurred variant, then draws the glass in a custom fragment shader
• the normal rounded glass path uses the card bounds / corner radius to estimate edge distance, then uses that edge band to drive:
  • Snell's law of refraction
  • blur/body mix
  • specular highlight / fresnel-ish lift
• there is also a shape mask path used for the lockscreen clock. the shader receives a second texture mask and derives edge behavior from the glyph shape instead of only from a rounded rect
• the blur is separable and baked in two compute passes, then reused until settings or source content actually require a rebake

contributions to this tweak are welcomed