Funnel chart

Staged conversion / loss visualisation. Each stage is a horizontal band; band width reflects remaining count relative to the widest stage.

The demo plots NASA's Mercury Seven astronaut selection, 1958–59: 508 military test pilots invited → 110 records- reviewed → 32 screened at the Lovelace Clinic + Wright-Patterson AFB → 18 finalists → 7 selected on 9 April 1959. The narrowest funnel in spaceflight history.

Source: Mercury Seven — Wikipedia

Public surface

use wisp_chart::topology::{Funnel, FunnelStage};
use wisp_chart::color::Color;

let c = |hex| Color::from_hex(hex).unwrap();
let f = Funnel::new(vec![
    FunnelStage::new("Visited",   10000.0, c("#0072b2")),
    FunnelStage::new("Signed up",  4000.0, c("#56b4e9")),
    FunnelStage::new("Activated",  1800.0, c("#7faedc")),
    FunnelStage::new("Converted",   600.0, c("#a3c7ea")),
]);
let g = f.emit_graphics(&theme, Vec2::new(400.0, 300.0));