When painting a scatter plot we sometimes want to paint hundreds of thousands of points (filled circles) on screen every frame.
In this PR the font texture atlas is pre-populated with some filled circled of various radii. These are then used when painting (small) filled circled, which means A LOT less triangles and vertices are generated for them.
In a new benchmark we can see a 10x speedup in circle tessellation, but the the real benefit comes in the painting of these circles: since we generate a lot less vertices, the backend painter has less to do.
In a real-life scenario with a lot of things being painted (including around 100k points) I saw tessellation go from 35ms -> 7ms and painting go from 45ms -> 1ms. This means the total frame time went from 80ms to 8ms, or a 10x speedup.
The epaint tessellator uses "feathering" to accomplish anti-aliasing. This PS allows you to control the feathering size, i.e. how blurry the edges of epaint shapes are.
This changes the interface of Tessellator slightly, and renames some options in TessellationOptions.
* Rename epaint feature "persistence" to "serialize"
* Add separate "serialize" feature to egui
* egui_demo_lib: separate serialize and persistence features
* Add App::persist_native_window and App::persist_egui_memory
Controls what gets persisted
* Tweak style
More compact, less round, less noisy
* Button text is now same size as body text
* The rounder corners are now less rounded
* Collapsing headers no longer have a frame around them
* Combo-boxes looks better when opened
* Slightly more muted colors
* Remove extra line spacing after `\n` (i.e. between paragraphs)
* Thinner scrollbars
* Tweak light mode
* Tweak shadows
* Fix broken doc link
* Add style tweak to CHANGELOG
