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use petgraph::{ stable_graph::{NodeIndex, StableUnGraph}, visit::{EdgeRef, IntoEdgeReferences}, }; pub type DefaultNodeIdx = NodeIndex<petgraph::stable_graph::DefaultIx>; const FORCE_CHARGE: f32 = 12000.0; const FORCE_SPRING: f32 = 0.3; const FORCE_MAX: f32 = 280.0; const NODE_SPEED: f32 = 7000.0; const DAMPING_FACTOR: f32 = 0.95; pub struct Node<D> { pub x: f32, pub y: f32, vx: f32, vy: f32, ax: f32, ay: f32, mass: f32, is_anchor: bool, pub data: D, } impl<D> Node<D> { fn apply_force(&mut self, fx: f32, fy: f32, dt: f32) { self.ax += fx.max(-FORCE_MAX).min(FORCE_MAX) * dt; self.ay += fy.max(-FORCE_MAX).min(FORCE_MAX) * dt; } fn update(&mut self, dt: f32) { self.vx = (self.vx + self.ax * dt * NODE_SPEED) * DAMPING_FACTOR; self.vy = (self.vy + self.ay * dt * NODE_SPEED) * DAMPING_FACTOR; self.x += self.vx * dt; self.y += self.vy * dt; self.ax = 0.0; self.ay = 0.0; } } pub struct Edge; pub struct ForceGraph<D> { graph: StableUnGraph<Node<D>, Edge>, } impl<D> ForceGraph<D> { pub fn new() -> Self { ForceGraph { graph: StableUnGraph::default(), } } pub fn get_graph(&self) -> &StableUnGraph<Node<D>, Edge> { &self.graph } pub fn add_node( &mut self, x: f32, y: f32, data: D, mass: f32, is_anchor: bool, ) -> DefaultNodeIdx { self.graph.add_node(Node { x, y, vx: 0.0, vy: 0.0, ax: 0.0, ay: 0.0, mass, is_anchor, data, }) } pub fn remove_node(&mut self, idx: DefaultNodeIdx) { self.graph.remove_node(idx); } pub fn add_edge(&mut self, n1_idx: DefaultNodeIdx, n2_idx: DefaultNodeIdx) { self.graph.update_edge(n1_idx, n2_idx, Edge); } pub fn clear(&mut self) { self.graph.clear(); } pub fn update(&mut self, dt: f32) { if self.graph.node_count() == 0 { return; } let first_node_idx = self .graph .node_indices() .next() .expect("first node missing"); let mut bfs = petgraph::visit::Bfs::new(&self.graph, first_node_idx); while let Some(n1) = bfs.next(&self.graph) { let mut edges = self.graph.neighbors(n1).detach(); while let Some(n2) = edges.next_node(&self.graph) { let f = attract_nodes(&self.graph[n1], &self.graph[n2]); self.graph[n1].apply_force(f.0, f.1, dt); } } let mut bfs1 = petgraph::visit::Bfs::new(&self.graph, first_node_idx); while let Some(n1) = bfs1.next(&self.graph) { if self.graph[n1].is_anchor { continue; } let mut bfs2 = petgraph::visit::Bfs::new(&self.graph, n1); bfs2.next(&self.graph); while let Some(n2) = bfs2.next(&self.graph) { let f = repel_nodes(&self.graph[n1], &self.graph[n2]); self.graph[n1].apply_force(f.0, f.1, dt); } self.graph[n1].update(dt); } } pub fn visit_nodes<F: FnMut(&Node<D>)>(&self, mut cb: F) { for n_idx in self.graph.node_indices() { cb(&self.graph[n_idx]); } } pub fn visit_edges<F: FnMut(&Node<D>, &Node<D>)>(&self, mut cb: F) { for edge_ref in self.graph.edge_references() { let source = &self.graph[edge_ref.source()]; let target = &self.graph[edge_ref.target()]; cb(source, target); } } } fn attract_nodes<D>(n1: &Node<D>, n2: &Node<D>) -> (f32, f32) { let mut dx = n2.x - n1.x; let mut dy = n2.y - n1.y; let distance = if dx == 0.0 && dy == 0.0 { 1.0 } else { (dx * dx + dy * dy).sqrt() }; dx /= distance; dy /= distance; let strength = 1.0 * FORCE_SPRING * distance * 0.5; (dx * strength, dy * strength) } fn repel_nodes<D>(n1: &Node<D>, n2: &Node<D>) -> (f32, f32) { let mut dx = n2.x - n1.x; let mut dy = n2.y - n1.y; let distance = if dx == 0.0 && dy == 0.0 { 1.0 } else { (dx * dx + dy * dy).sqrt() }; dx /= distance; dy /= distance; let strength = -FORCE_CHARGE * ((n1.mass * n2.mass) / (distance * distance)); (dx * strength, dy * strength) }