mesh

triangle build
auto-invalidation of cache

.gitignore

@@ -4,4 +4,5 @@ build/ffi/
 *.a
 target/
 assets/old/
+assets/icons/
 Cargo.lock

crates/femm-app/src/doc_canvas.rs

@@ -1,6 +1,7 @@
 //! draws a FemmDoc on an iced canvas: nodes, segments, arcs, block labels, with pan/zoom and click-to-add.
 
 use femm_doc_mag::FemmDoc;
+use femm_doc_mag::mesh::Mesh;
 use iced::widget::canvas::{
     self, Action, Canvas, Event, Frame, Geometry, Path, Stroke, Text, path::Builder,
 };
@@ -20,6 +21,8 @@ const LABEL_COLOR: Color = Color::from_rgb(0.25, 0.45, 0.85);
 const PENDING_COLOR: Color = Color::from_rgb(0.85, 0.30, 0.30);
 const SELECT_COLOR: Color = Color::from_rgb(0.95, 0.20, 0.20);
 const SELECT_STROKE: f32 = 2.4;
+const MESH_COLOR: Color = Color::from_rgba(0.55, 0.55, 0.55, 0.55);
+const MESH_STROKE: f32 = 0.5;
 
 /// active editing mode on the canvas.
 #[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
@@ -56,9 +59,13 @@ pub struct ViewState {
     cursor_world: Option<(f64, f64)>,
 }
 
-/// constructs the canvas widget for a doc reference.
-pub fn view<'a>(doc: &'a FemmDoc, tool: Tool) -> Element<'a, CanvasMessage> {
-    Canvas::new(DocCanvas { doc, tool })
+/// constructs the canvas widget for a doc reference and an optional mesh overlay.
+pub fn view<'a>(
+    doc: &'a FemmDoc,
+    tool: Tool,
+    mesh: Option<&'a Mesh>,
+) -> Element<'a, CanvasMessage> {
+    Canvas::new(DocCanvas { doc, tool, mesh })
         .width(Length::Fill)
         .height(Length::Fill)
         .into()
@@ -67,6 +74,7 @@ pub fn view<'a>(doc: &'a FemmDoc, tool: Tool) -> Element<'a, CanvasMessage> {
 struct DocCanvas<'a> {
     doc: &'a FemmDoc,
     tool: Tool,
+    mesh: Option<&'a Mesh>,
 }
 
 impl<'a> canvas::Program<CanvasMessage> for DocCanvas<'a> {
@@ -214,6 +222,27 @@ impl<'a> canvas::Program<CanvasMessage> for DocCanvas<'a> {
 
         let view = ViewTransform::fit(self.doc, bounds, state);
 
+        if let Some(mesh) = self.mesh {
+            for el in &mesh.elements {
+                let (Some(a), Some(b), Some(c)) = (
+                    mesh.nodes.get(el.v0 as usize),
+                    mesh.nodes.get(el.v1 as usize),
+                    mesh.nodes.get(el.v2 as usize),
+                ) else { continue };
+                let pa = view.map(a.x, a.y);
+                let pb = view.map(b.x, b.y);
+                let pc = view.map(c.x, c.y);
+                let tri = Path::new(|p| {
+                    p.move_to(pa);
+                    p.line_to(pb);
+                    p.line_to(pc);
+                    p.close();
+                });
+                frame.stroke(&tri,
+                    Stroke::default().with_width(MESH_STROKE).with_color(MESH_COLOR));
+            }
+        }
+
         for s in &self.doc.segments {
             if let (Some(p0), Some(p1)) =
                 (self.doc.nodes.get(s.n0 as usize), self.doc.nodes.get(s.n1 as usize))

crates/femm-app/src/main.rs

@@ -4,21 +4,25 @@ mod doc_canvas;
 
 use doc_canvas::{CanvasMessage, Tool};
 use femm_doc_mag::FemmDoc;
+use femm_doc_mag::mesh::Mesh;
 use iced::widget::{button, column, container, row, text};
 use iced::{Element, Length, Task};
 
 const DEMO_FEM: &str = include_str!("../assets/demo.fem");
 const ADD_TOLERANCE: f64 = 0.5;
+const MIN_ANGLE_DEG: f64 = 30.0;
 
 #[derive(Debug, Clone)]
 enum Message {
     OpenFem,
     SelectTool(Tool),
     Canvas(CanvasMessage),
+    RunMesh,
 }
 
 struct App {
     doc: FemmDoc,
+    mesh: Option<Mesh>,
     source_label: String,
     status: String,
     tool: Tool,
@@ -29,6 +33,7 @@ impl App {
         let doc = FemmDoc::parse(DEMO_FEM).unwrap_or_default();
         let app = App {
             doc,
+            mesh: None,
             source_label: String::from("demo.fem (embedded)"),
             status: String::new(),
             tool: Tool::Select,
@@ -57,6 +62,7 @@ impl App {
                     match FemmDoc::open(&path) {
                         Ok(d) => {
                             self.doc = d;
+                            self.mesh = None;
                             self.source_label = label;
                             self.status = String::new();
                         }
@@ -69,14 +75,28 @@ impl App {
             Message::SelectTool(t) => {
                 self.tool = t;
             }
+            Message::RunMesh => {
+                match run_mesh(&self.doc) {
+                    Ok(m) => {
+                        self.status = format!("meshed: {} nodes, {} elements", m.nodes.len(), m.elements.len());
+                        self.mesh = Some(m);
+                    }
+                    Err(e) => {
+                        self.mesh = None;
+                        self.status = format!("mesh failed: {e}");
+                    }
+                }
+            }
             Message::Canvas(CanvasMessage::Click { world, tool }) => {
                 match tool {
                     Tool::AddNode => {
                         let idx = self.doc.add_node(world.0, world.1, ADD_TOLERANCE);
+                        self.mesh = None;
                         self.status = format!("node {idx} at ({:.3}, {:.3})", world.0, world.1);
                     }
                     Tool::AddBlockLabel => {
                         let idx = self.doc.add_block_label(world.0, world.1, ADD_TOLERANCE);
+                        self.mesh = None;
                         self.status = format!("block label {idx} at ({:.3}, {:.3})", world.0, world.1);
                     }
                     Tool::Select | Tool::AddSegment => {}
@@ -86,6 +106,7 @@ impl App {
                 let n0 = self.doc.add_node(from.0, from.1, ADD_TOLERANCE) as i32;
                 let n1 = self.doc.add_node(to.0,   to.1,   ADD_TOLERANCE) as i32;
                 if self.doc.add_segment(n0, n1) {
+                    self.mesh = None;
                     self.status = format!(
                         "segment {n0} -> {n1}  ({} total)",
                         self.doc.segments.len(),
@@ -104,6 +125,7 @@ impl App {
                 let a = self.doc.delete_selected_arcs();
                 let b = self.doc.delete_selected_block_labels();
                 let total = n + s + a + b;
+                if total > 0 { self.mesh = None; }
                 self.status = if total == 0 {
                     String::from("nothing selected")
                 } else {
@@ -130,12 +152,14 @@ impl App {
             tool_button("Add Node",    Tool::AddNode,       self.tool),
             tool_button("Add Segment", Tool::AddSegment,    self.tool),
             tool_button("Add Label",   Tool::AddBlockLabel, self.tool),
+            button("Mesh").on_press(Message::RunMesh),
             text(&self.source_label).size(13),
             stats,
         ]
         .spacing(8);
 
-        let canvas = doc_canvas::view(&self.doc, self.tool).map(Message::Canvas);
+        let canvas = doc_canvas::view(&self.doc, self.tool, self.mesh.as_ref())
+            .map(Message::Canvas);
 
         let mut body = column![toolbar].spacing(8).padding(12);
         body = body.push(canvas);
@@ -150,6 +174,48 @@ impl App {
     }
 }
 
+/// saves the doc to a temp .fem and matching .poly, invokes Triangle, and reads back the mesh.
+fn run_mesh(doc: &FemmDoc) -> Result<Mesh, String> {
+    let dir = std::env::temp_dir().join("femm42-mesh");
+    std::fs::create_dir_all(&dir).map_err(|e| format!("temp dir: {e}"))?;
+    let stem = dir.join("active");
+    let fem_path  = stem.with_extension("fem");
+    let poly_path = stem.with_extension("poly");
+
+    doc.save(&fem_path).map_err(|e| format!("save .fem: {e}"))?;
+    doc.save_poly(&poly_path).map_err(|e| format!("save .poly: {e}"))?;
+
+    let triangle = locate_triangle()
+        .ok_or_else(|| String::from("triangle binary not found at build/triangle/triangle - run scripts/macos/build_triangle.sh"))?;
+
+    let stem_str = stem.to_str().ok_or_else(|| String::from("non-utf8 path"))?;
+    let status = std::process::Command::new(&triangle)
+        .args([
+            "-p", "-P", "-e", "-A", "-a", "-z", "-Q", "-I",
+            &format!("-q{MIN_ANGLE_DEG}"),
+        ])
+        .arg(stem_str)
+        .status()
+        .map_err(|e| format!("exec triangle: {e}"))?;
+    if !status.success() {
+        return Err(format!("triangle exited with {status}"));
+    }
+
+    Mesh::load(&stem).map_err(|e| format!("read mesh: {e}"))
+}
+
+/// resolves the Triangle binary path, preferring the build dir then $PATH.
+fn locate_triangle() -> Option<std::path::PathBuf> {
+    let here = std::env::current_dir().ok()?;
+    let built = here.join("build/triangle/triangle");
+    if built.is_file() { return Some(built); }
+    if let Ok(env_path) = std::env::var("FEMM_TRIANGLE") {
+        let p = std::path::PathBuf::from(env_path);
+        if p.is_file() { return Some(p); }
+    }
+    None
+}
+
 /// flips the selected flag on whichever entity sits nearest to (x, y) in doc world coords.
 fn toggle_closest(doc: &mut FemmDoc, x: f64, y: f64) {
     use femm_doc_mag::geom_math::{

crates/femm-doc-mag/src/lib.rs

@@ -7,6 +7,7 @@ pub mod parser;
 pub mod writer;
 pub mod edit;
 pub mod poly;
+pub mod mesh;
 
 use num_complex::Complex64;
 

crates/femm-doc-mag/src/mesh.rs

@@ -0,0 +1,161 @@
+//! readers for Triangle's .node and .ele output files.
+
+use std::path::Path;
+use thiserror::Error;
+
+/// 2D triangular mesh consumed by the canvas overlay and by the post-processor.
+#[derive(Debug, Default, Clone)]
+pub struct Mesh {
+    pub nodes:    Vec<MeshNode>,
+    pub elements: Vec<MeshElement>,
+}
+
+/// position and optional boundary marker for a single mesh node.
+#[derive(Debug, Clone, Copy)]
+pub struct MeshNode {
+    pub x: f64,
+    pub y: f64,
+    pub marker: i32,
+}
+
+/// triangle element with three zero-based node indices and an optional region attribute.
+#[derive(Debug, Clone, Copy)]
+pub struct MeshElement {
+    pub v0: u32,
+    pub v1: u32,
+    pub v2: u32,
+    pub attribute: i32,
+}
+
+#[derive(Debug, Error)]
+pub enum MeshLoadError {
+    #[error("io error: {0}")]
+    Io(#[from] std::io::Error),
+    #[error("malformed header in {file}: {reason}")]
+    BadHeader { file: &'static str, reason: String },
+    #[error("malformed row in {file}: {reason}")]
+    BadRow { file: &'static str, reason: String },
+}
+
+impl Mesh {
+    /// loads .1.node and .1.ele next to the given path stem (Triangle's default output).
+    pub fn load(stem: impl AsRef<Path>) -> Result<Self, MeshLoadError> {
+        let stem = stem.as_ref();
+        let node_path = with_extension(stem, "1.node");
+        let ele_path  = with_extension(stem, "1.ele");
+        let nodes = parse_node(&std::fs::read_to_string(&node_path)?)?;
+        let elements = parse_ele(&std::fs::read_to_string(&ele_path)?)?;
+        Ok(Mesh { nodes, elements })
+    }
+}
+
+/// parses a .node file: header `count 2 0 nbm`, then count rows of `idx x y [marker]`.
+pub fn parse_node(src: &str) -> Result<Vec<MeshNode>, MeshLoadError> {
+    let mut lines = src.lines().filter(|l| !l.trim_start().starts_with('#') && !l.trim().is_empty());
+    let header = lines.next().ok_or(MeshLoadError::BadHeader {
+        file: ".node",
+        reason: "empty file".into(),
+    })?;
+    let mut hparts = header.split_whitespace();
+    let count: usize = hparts.next()
+        .and_then(|s| s.parse().ok())
+        .ok_or(MeshLoadError::BadHeader { file: ".node", reason: format!("expected count, got {header:?}") })?;
+    let _dim = hparts.next();
+    let _attrs = hparts.next();
+    let has_marker = hparts.next().map(|s| s.trim() == "1").unwrap_or(false);
+
+    let mut nodes = Vec::with_capacity(count);
+    for line in lines.take(count) {
+        let mut parts = line.split_whitespace();
+        let _idx: u32 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".node", reason: line.into() })?;
+        let x: f64 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".node", reason: line.into() })?;
+        let y: f64 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".node", reason: line.into() })?;
+        let marker = if has_marker {
+            parts.next().and_then(|s| s.parse().ok()).unwrap_or(0)
+        } else {
+            0
+        };
+        nodes.push(MeshNode { x, y, marker });
+    }
+    Ok(nodes)
+}
+
+/// parses a .ele file: header `count 3 natt`, then count rows of `idx v0 v1 v2 [attr0 ...]`.
+pub fn parse_ele(src: &str) -> Result<Vec<MeshElement>, MeshLoadError> {
+    let mut lines = src.lines().filter(|l| !l.trim_start().starts_with('#') && !l.trim().is_empty());
+    let header = lines.next().ok_or(MeshLoadError::BadHeader {
+        file: ".ele",
+        reason: "empty file".into(),
+    })?;
+    let mut hparts = header.split_whitespace();
+    let count: usize = hparts.next()
+        .and_then(|s| s.parse().ok())
+        .ok_or(MeshLoadError::BadHeader { file: ".ele", reason: format!("expected count, got {header:?}") })?;
+    let _nodes_per = hparts.next();
+    let natt: usize = hparts.next().and_then(|s| s.parse().ok()).unwrap_or(0);
+
+    let mut elements = Vec::with_capacity(count);
+    for line in lines.take(count) {
+        let mut parts = line.split_whitespace();
+        let _idx: u32 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".ele", reason: line.into() })?;
+        let v0: u32 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".ele", reason: line.into() })?;
+        let v1: u32 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".ele", reason: line.into() })?;
+        let v2: u32 = parts.next().and_then(|s| s.parse().ok())
+            .ok_or(MeshLoadError::BadRow { file: ".ele", reason: line.into() })?;
+        let attribute = if natt > 0 {
+            parts.next().and_then(|s| s.parse::<f64>().ok()).map(|f| f as i32).unwrap_or(0)
+        } else {
+            0
+        };
+        elements.push(MeshElement { v0, v1, v2, attribute });
+    }
+    Ok(elements)
+}
+
+fn with_extension(stem: &Path, ext: &str) -> std::path::PathBuf {
+    let mut s = stem.to_path_buf();
+    s.set_extension(ext);
+    s
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_node_with_markers() {
+        // 3 nodes, 2D, no attributes, with markers; comment line at the start is ignored.
+        let src = "# triangle .node\n3 2 0 1\n0 0.0 0.0 2\n1 1.0 0.0 0\n2 0.0 1.0 0\n";
+        let nodes = parse_node(src).unwrap();
+        assert_eq!(nodes.len(), 3);
+        assert_eq!(nodes[0].marker, 2);
+        assert!((nodes[2].y - 1.0).abs() < 1e-12);
+    }
+
+    #[test]
+    fn parses_ele_with_region_attribute() {
+        // 2 triangles, 3 nodes per element, 1 region attribute column.
+        let src = "2 3 1\n0 0 1 2 1.0\n1 1 2 3 2.0\n";
+        let els = parse_ele(src).unwrap();
+        assert_eq!(els.len(), 2);
+        assert_eq!(els[0].v0, 0);
+        assert_eq!(els[0].v1, 1);
+        assert_eq!(els[0].v2, 2);
+        assert_eq!(els[0].attribute, 1);
+        assert_eq!(els[1].attribute, 2);
+    }
+
+    #[test]
+    fn parses_node_without_marker_column() {
+        let src = "2 2 0 0\n0 0.0 0.0\n1 1.0 0.0\n";
+        let nodes = parse_node(src).unwrap();
+        assert_eq!(nodes.len(), 2);
+        assert_eq!(nodes[0].marker, 0);
+    }
+}

scripts/macos/build_triangle.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+BUILD="${BUILD:-$ROOT/build/triangle}"
+
+mkdir -p "$BUILD"
+
+CC=${CC:-clang}
+CFLAGS=${CFLAGS:-"-O2 -w"}
+
+$CC $CFLAGS -o "$BUILD/triangle" "$ROOT/triangle/triangle.c" -lm
+
+echo "built: $BUILD/triangle"

triangle/triangle.c

@@ -1469,7 +1469,7 @@ VOID *memptr;
 
 void syntax()
 {
-	ShellExecute(NULL, "open", "https://www.cs.cmu.edu/~quake/triangle.switch.html", NULL, NULL, SW_SHOWNORMAL);
+	printf("Triangle switches: https://www.cs.cmu.edu/~quake/triangle.switch.html\n");
 	triexit(0);
 }
 
@@ -1485,7 +1485,7 @@ void syntax()
 
 void info()
 {
-	ShellExecute(NULL, "open", "https://www.cs.cmu.edu/~quake/triangle.help.html", NULL, NULL, SW_SHOWNORMAL);
+	printf("Triangle help: https://www.cs.cmu.edu/~quake/triangle.help.html\n");
 	triexit(0);
 }