feat(pineal): cierra stub flow — diagrama Sankey

Fase F: quinto stub de pineal cerrado.

- layout — pipeline Sankey: columnas por longest-path en el DAG
  (back-edges detectadas por DFS y descartadas para romper ciclos),
  valor de nodo = max(entrante, saliente), apilado vertical por columna
  escalado a la altura, una pasada de barycenter para reducir cruces,
  anclas de cada banda en los bordes de sus nodos.
- ribbon — teselado de bandas como triangle-strip con curva S
  (x lineal, y por smoothstep → tangentes horizontales). paint_ribbon
  + paint_sankey (ribbons al fondo, nodos encima).

Painters agnósticos (trait Canvas). 6 tests verdes (columnas, ciclos
sin loop infinito, proporcionalidad, conteo de draw calls).

Pineal: 5/6 stubs cerrados. Resta mesh (viz de grafos: force-directed
+ Sugiyama + tree layout — módulo, no stub).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
sergio
2026-05-20 15:06:58 +00:00
parent 94ea0eaa53
commit 0042fe3f1f
3 changed files with 418 additions and 11 deletions
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//! Layout de un diagrama Sankey.
//!
//! Pipeline: columnas por longest-path en el DAG (back-edges descartadas)
//! → valor de nodo = max(entrada, salida) → apilado vertical por columna
//! con una pasada de barycenter para reducir cruces → anclas de cada
//! banda (link) en los bordes de sus nodos.
use pineal_render::{Point, Rect};
/// Un nodo del Sankey.
#[derive(Debug, Clone)]
pub struct SankeyNode {
pub label: String,
}
impl SankeyNode {
pub fn new(label: impl Into<String>) -> Self {
Self { label: label.into() }
}
}
/// Un flujo dirigido `source → target` con un caudal `value`.
#[derive(Debug, Clone, Copy)]
pub struct SankeyLink {
pub source: usize,
pub target: usize,
pub value: f64,
}
/// Caja de un nodo ya ubicada en el lienzo.
#[derive(Debug, Clone)]
pub struct NodeBox {
pub rect: Rect,
pub column: usize,
}
/// Banda de un link: cuatro anclas (arriba/abajo en origen y destino).
#[derive(Debug, Clone, Copy)]
pub struct LinkBand {
pub link: usize,
pub src_top: Point,
pub src_bot: Point,
pub dst_top: Point,
pub dst_bot: Point,
}
/// Layout completo: cajas de nodos + bandas de links.
#[derive(Debug, Clone, Default)]
pub struct SankeyLayout {
pub nodes: Vec<NodeBox>,
pub links: Vec<LinkBand>,
}
/// Calcula el layout de un Sankey dentro de `area`.
pub fn compute_layout(
nodes: &[SankeyNode],
links: &[SankeyLink],
area: Rect,
node_width: f32,
node_gap: f32,
) -> SankeyLayout {
let n = nodes.len();
if n == 0 || area.w <= 0.0 || area.h <= 0.0 {
return SankeyLayout::default();
}
let valid: Vec<&SankeyLink> = links
.iter()
.filter(|l| l.source < n && l.target < n && l.source != l.target && l.value > 0.0)
.collect();
let columns = assign_columns(n, &valid);
let n_cols = columns.iter().copied().max().unwrap_or(0) + 1;
// Valor de cada nodo = max(suma entrante, suma saliente).
let mut in_sum = vec![0.0f64; n];
let mut out_sum = vec![0.0f64; n];
for l in &valid {
in_sum[l.target] += l.value;
out_sum[l.source] += l.value;
}
let node_value: Vec<f64> = (0..n).map(|i| in_sum[i].max(out_sum[i]).max(0.0)).collect();
// Nodos por columna.
let mut by_col: Vec<Vec<usize>> = vec![Vec::new(); n_cols];
for (i, &c) in columns.iter().enumerate() {
by_col[c].push(i);
}
// Escala vertical: la columna más cargada llena `area.h` (con gaps).
let max_col_value = by_col
.iter()
.map(|col| col.iter().map(|&i| node_value[i]).sum::<f64>())
.fold(0.0f64, f64::max)
.max(1e-9);
let max_col_count = by_col.iter().map(|c| c.len()).max().unwrap_or(1).max(1);
let usable_h = (area.h - node_gap * (max_col_count.saturating_sub(1)) as f32).max(1.0);
let v_scale = usable_h as f64 / max_col_value;
// Una pasada de barycenter para ordenar cada columna.
barycenter_pass(&mut by_col, &valid, &columns);
// Geometría de cada nodo.
let col_step = if n_cols > 1 {
(area.w - node_width) / (n_cols - 1) as f32
} else {
0.0
};
let mut boxes = vec![
NodeBox { rect: Rect::new(0.0, 0.0, 0.0, 0.0), column: 0 };
n
];
for (c, col) in by_col.iter().enumerate() {
let mut y = area.y;
for &i in col {
let h = (node_value[i] * v_scale) as f32;
let x = area.x + c as f32 * col_step;
boxes[i] = NodeBox {
rect: Rect::new(x, y, node_width, h.max(1.0)),
column: c,
};
y += h + node_gap;
}
}
// Bandas de links: apiladas en el borde derecho del origen y el
// borde izquierdo del destino, en el orden de aparición.
let mut src_cursor = vec![0.0f32; n];
let mut dst_cursor = vec![0.0f32; n];
let mut bands = Vec::with_capacity(valid.len());
for (vi, l) in valid.iter().enumerate() {
let sb = &boxes[l.source].rect;
let tb = &boxes[l.target].rect;
let thick_s = (l.value * v_scale) as f32;
let s_y0 = sb.y + src_cursor[l.source];
let t_y0 = tb.y + dst_cursor[l.target];
src_cursor[l.source] += thick_s;
dst_cursor[l.target] += thick_s;
// El índice real del link en el slice original.
let link_idx = links
.iter()
.position(|x| {
x.source == l.source && x.target == l.target && x.value == l.value
})
.unwrap_or(vi);
bands.push(LinkBand {
link: link_idx,
src_top: Point::new(sb.right(), s_y0),
src_bot: Point::new(sb.right(), s_y0 + thick_s),
dst_top: Point::new(tb.x, t_y0),
dst_bot: Point::new(tb.x, t_y0 + thick_s),
});
}
SankeyLayout { nodes: boxes, links: bands }
}
/// Columna de cada nodo = longest-path desde una fuente. Las back-edges
/// (detectadas por DFS) se descartan para romper ciclos.
fn assign_columns(n: usize, links: &[&SankeyLink]) -> Vec<usize> {
let mut adj: Vec<Vec<usize>> = vec![Vec::new(); n];
for l in links {
adj[l.source].push(l.target);
}
// DFS marcando back-edges (destino en la pila actual).
let mut state = vec![0u8; n]; // 0=blanco 1=en-pila 2=hecho
let mut back: Vec<(usize, usize)> = Vec::new();
for s in 0..n {
if state[s] != 0 {
continue;
}
let mut stack = vec![(s, 0usize)];
state[s] = 1;
while let Some(&mut (u, ref mut i)) = stack.last_mut() {
if *i < adj[u].len() {
let v = adj[u][*i];
*i += 1;
match state[v] {
0 => {
state[v] = 1;
stack.push((v, 0));
}
1 => back.push((u, v)),
_ => {}
}
} else {
state[u] = 2;
stack.pop();
}
}
}
// Longest-path en el DAG (sin back-edges) vía relajación topológica.
let mut indeg = vec![0usize; n];
let mut dag: Vec<Vec<usize>> = vec![Vec::new(); n];
for l in links {
if !back.contains(&(l.source, l.target)) {
dag[l.source].push(l.target);
indeg[l.target] += 1;
}
}
let mut col = vec![0usize; n];
let mut queue: Vec<usize> = (0..n).filter(|&i| indeg[i] == 0).collect();
let mut head = 0;
while head < queue.len() {
let u = queue[head];
head += 1;
for &v in &dag[u] {
col[v] = col[v].max(col[u] + 1);
indeg[v] -= 1;
if indeg[v] == 0 {
queue.push(v);
}
}
}
col
}
/// Reordena los nodos de cada columna por el promedio de las posiciones
/// de sus vecinos (barycenter heuristic), una pasada izquierda→derecha.
fn barycenter_pass(by_col: &mut [Vec<usize>], links: &[&SankeyLink], columns: &[usize]) {
let n = columns.len();
let mut order_in_col = vec![0usize; n];
for col in by_col.iter() {
for (pos, &i) in col.iter().enumerate() {
order_in_col[i] = pos;
}
}
for c in 1..by_col.len() {
let bary: Vec<(usize, f64)> = by_col[c]
.iter()
.map(|&node| {
let mut sum = 0.0;
let mut cnt = 0.0;
for l in links {
if l.target == node && columns[l.source] == c - 1 {
sum += order_in_col[l.source] as f64;
cnt += 1.0;
}
}
(node, if cnt > 0.0 { sum / cnt } else { f64::MAX })
})
.collect();
let mut sorted = bary;
sorted.sort_by(|a, b| a.1.partial_cmp(&b.1).unwrap_or(std::cmp::Ordering::Equal));
by_col[c] = sorted.into_iter().map(|(node, _)| node).collect();
for (pos, &i) in by_col[c].iter().enumerate() {
order_in_col[i] = pos;
}
}
}
#[cfg(test)]
mod tests {
use super::*;
fn nodes(n: usize) -> Vec<SankeyNode> {
(0..n).map(|i| SankeyNode::new(format!("n{i}"))).collect()
}
#[test]
fn empty_input() {
let l = compute_layout(&[], &[], Rect::new(0.0, 0.0, 100.0, 100.0), 20.0, 4.0);
assert!(l.nodes.is_empty());
}
#[test]
fn chain_assigns_increasing_columns() {
// 0 → 1 → 2
let links = [
SankeyLink { source: 0, target: 1, value: 5.0 },
SankeyLink { source: 1, target: 2, value: 5.0 },
];
let l = compute_layout(&nodes(3), &links, Rect::new(0.0, 0.0, 300.0, 100.0), 20.0, 4.0);
assert_eq!(l.nodes[0].column, 0);
assert_eq!(l.nodes[1].column, 1);
assert_eq!(l.nodes[2].column, 2);
assert_eq!(l.links.len(), 2);
}
#[test]
fn back_edge_does_not_loop_forever() {
// ciclo 0 → 1 → 0 ; debe terminar y no panickear.
let links = [
SankeyLink { source: 0, target: 1, value: 3.0 },
SankeyLink { source: 1, target: 0, value: 1.0 },
];
let l = compute_layout(&nodes(2), &links, Rect::new(0.0, 0.0, 200.0, 100.0), 20.0, 4.0);
assert_eq!(l.nodes.len(), 2);
}
#[test]
fn node_height_proportional_to_flow() {
// 0 manda 10 a 1 y 1 a 2 ; nodo 0 más "grueso" que nodo 2.
let links = [
SankeyLink { source: 0, target: 1, value: 10.0 },
SankeyLink { source: 0, target: 2, value: 2.0 },
];
let l = compute_layout(&nodes(3), &links, Rect::new(0.0, 0.0, 200.0, 200.0), 20.0, 4.0);
assert!(l.nodes[0].rect.h > l.nodes[2].rect.h);
}
}
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//! `pineal-flow` — diagramas Sankey.
//!
//! Pipeline (sección 3.7 del ARCHITECTURE.md):
//! 1. Columnas via longest-path en el DAG (back-edges drop).
//! 2. Flow por nodo = max(in_value, out_value).
//! 3. Barycenter ordering con inversion-count crossings.
//! 4. Stripes por edge dentro de cada lado del nodo.
//! 5. Ribbons como triangle-strip de béziers, un draw call por
//! ribbon, color por vértice.
//! Pipeline:
//! 1. Columnas por longest-path en el DAG (back-edges descartadas).
//! 2. Valor de nodo = max(caudal entrante, caudal saliente).
//! 3. Apilado vertical por columna + una pasada de barycenter.
//! 4. Bandas (ribbons) como triangle-strips con curva S (`smoothstep`).
//!
//! - [`layout`] — cómputo del layout (agnóstico).
//! - [`ribbon`] — teselado + painters contra `Canvas`.
#![forbid(unsafe_code)]
#![allow(dead_code)]
pub mod layout {}
pub mod ribbon {}
pub mod element {}
pub mod layout;
pub mod ribbon;
pub use layout::{compute_layout, LinkBand, NodeBox, SankeyLayout, SankeyLink, SankeyNode};
pub use ribbon::{paint_ribbon, paint_sankey, ribbon_strip};
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//! Tesela y dibuja las bandas (ribbons) de un Sankey.
//!
//! Cada banda es una franja con curva S: `x` avanza lineal entre nodos y
//! `y` interpola con `smoothstep`, lo que da tangentes horizontales en
//! ambos extremos (el look clásico de Sankey). Se emite como un triangle
//! strip `[top0,bot0,top1,bot1,…]`, un draw call por ribbon.
use crate::layout::{LinkBand, SankeyLayout};
use pineal_render::{Canvas, Color};
/// Segmentos por ribbon — controla la suavidad de la curva.
const RIBBON_SEGMENTS: usize = 24;
fn smoothstep(t: f32) -> f32 {
t * t * (3.0 - 2.0 * t)
}
/// Tesela una banda en coords interleaved `[x,y,…]` de un triangle strip.
pub fn ribbon_strip(band: &LinkBand) -> Vec<f32> {
let mut coords = Vec::with_capacity((RIBBON_SEGMENTS + 1) * 4);
for i in 0..=RIBBON_SEGMENTS {
let t = i as f32 / RIBBON_SEGMENTS as f32;
let e = smoothstep(t);
let x_top = band.src_top.x + (band.dst_top.x - band.src_top.x) * t;
let y_top = band.src_top.y + (band.dst_top.y - band.src_top.y) * e;
let x_bot = band.src_bot.x + (band.dst_bot.x - band.src_bot.x) * t;
let y_bot = band.src_bot.y + (band.dst_bot.y - band.src_bot.y) * e;
coords.push(x_top);
coords.push(y_top);
coords.push(x_bot);
coords.push(y_bot);
}
coords
}
/// Dibuja una sola banda con el color dado.
pub fn paint_ribbon(band: &LinkBand, color: Color, canvas: &mut dyn Canvas) {
let coords = ribbon_strip(band);
let colors = vec![color; coords.len() / 2];
canvas.fill_triangle_strip(&coords, &colors);
}
/// Dibuja un Sankey completo: ribbons primero (al fondo), nodos encima.
pub fn paint_sankey(
layout: &SankeyLayout,
node_color: Color,
link_color: Color,
canvas: &mut dyn Canvas,
) {
for band in &layout.links {
paint_ribbon(band, link_color, canvas);
}
for nb in &layout.nodes {
if nb.rect.w > 0.0 && nb.rect.h > 0.0 {
canvas.fill_rect(nb.rect, node_color);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::layout::{compute_layout, SankeyLink, SankeyNode};
use pineal_render::{PlanRecorder, Rect, RenderCmd};
#[test]
fn ribbon_strip_has_expected_vertex_count() {
let band = LinkBand {
link: 0,
src_top: pineal_render::Point::new(0.0, 0.0),
src_bot: pineal_render::Point::new(0.0, 10.0),
dst_top: pineal_render::Point::new(100.0, 50.0),
dst_bot: pineal_render::Point::new(100.0, 60.0),
};
let coords = ribbon_strip(&band);
assert_eq!(coords.len(), (RIBBON_SEGMENTS + 1) * 4);
}
#[test]
fn paint_sankey_emits_nodes_and_ribbons() {
let nodes = vec![
SankeyNode::new("a"),
SankeyNode::new("b"),
SankeyNode::new("c"),
];
let links = [
SankeyLink { source: 0, target: 1, value: 5.0 },
SankeyLink { source: 1, target: 2, value: 3.0 },
];
let layout = compute_layout(
&nodes,
&links,
Rect::new(0.0, 0.0, 300.0, 150.0),
18.0,
6.0,
);
let mut rec = PlanRecorder::new();
paint_sankey(&layout, Color::from_hex(0x335577), Color::from_hex(0x88aacc), &mut rec);
let cmds = rec.into_plan().cmds;
let rects = cmds.iter().filter(|c| matches!(c, RenderCmd::FillRect { .. })).count();
let strips = cmds.iter().filter(|c| matches!(c, RenderCmd::FillTriangleStrip { .. })).count();
assert_eq!(rects, 3, "un fill_rect por nodo");
assert_eq!(strips, 2, "un triangle strip por link");
}
}