Sunburst chart
Radial hierarchical layout — root at the centre, each depth radiates outward as a concentric ring. Child segments span the angular range of their parent.
The demo decomposes the Apollo program's $25.4 B lifetime cost (1973 dollars) by NASA centre and then by program element. The inner ring groups the four big centres (Marshall → Saturn V, Manned Spacecraft Center → CSM + LM, Kennedy → launch + tracking, HQ → R&D + ops); the outer ring breaks each group into its program-element line items. Marshall's Saturn V slice alone is 36 % of the whole pie — the most expensive single machine ever built.
Source: Apollo program — Costs — Wikipedia
Public surface
use wisp_chart::polar::{Sunburst, SunburstNode};
use wisp_chart::color::Color;
let c = |hex| Color::from_hex(hex).unwrap();
let s = Sunburst::new(SunburstNode::group("root", c("#888"), vec![
SunburstNode::group("Sales", c("#0072b2"), vec![
SunburstNode::leaf("NA", 30.0, c("#56b4e9")),
SunburstNode::leaf("EU", 20.0, c("#7faedc")),
SunburstNode::leaf("APAC", 15.0, c("#a3c7ea")),
]),
SunburstNode::group("Eng", c("#009e73"), vec![
SunburstNode::leaf("Platform", 25.0, c("#3eb893")),
SunburstNode::leaf("App", 20.0, c("#71cba8")),
]),
]))
.ring_width_px(30.0);
let g = s.emit_graphics(&theme, Vec2::new(320.0, 320.0));Layout
Depth 0 (the root) is NOT drawn — only its descendants. Depth 1
is the inner ring. Each child's angular span is
child_weight / parent_weight * parent_span. Leaf weights are
the supplied value; internal-node weights are computed as the
sum of descendant leaves.
When sunburst beats treemap
Sunburst is the right call when depth matters more than area precision. Reading a 4-level hierarchy is easier in concentric rings than in nested rectangles because the rings give visual isolation. Use treemap when leaf-area proportions are the primary read.