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Optimize tessellation of filled circles (#1616)

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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.
This commit is contained in:
Emil Ernerfeldt
2022-05-10 19:31:19 +02:00
committed by GitHub
parent 28efc0e1c8
commit 7b18fab7a4
12 changed files with 232 additions and 23 deletions
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14
egui_demo_lib/src/demo/misc_demo_window.rs
View File

@@ -158,6 +158,20 @@ impl View for MiscDemoWindow {
painter.line_segment([c, c + r * Vec2::angled(TAU * 3.0 / 8.0)], stroke);
});
});
CollapsingHeader::new("Many circles of different sizes")
.default_open(false)
.show(ui, |ui| {
ui.horizontal_wrapped(|ui| {
for i in 0..100 {
let r = i as f32 * 0.5;
let size = Vec2::splat(2.0 * r + 5.0);
let (rect, _response) = ui.allocate_at_least(size, Sense::hover());
ui.painter()
.circle_filled(rect.center(), r, ui.visuals().text_color());
}
});
});
}
}