1 files changed, 121 insertions, 0 deletions
diff --git a/src/dot.rs b/src/dot.rs
new file mode 100644
index 0000000..97f4ab1
--- /dev/null
+++ b/src/dot.rs
@@ -0,0 +1,121 @@
+use crate::*;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct DcelDotOptions {
+    pub twin: bool,
+    pub next: bool,
+    pub prev: bool,
+}
+
+impl DcelDotOptions {
+    pub fn none() -> Self {
+        Self {
+            twin: false,
+            next: false,
+            prev: false,
+        }
+    }
+
+    pub fn all() -> Self {
+        Self {
+            twin: true,
+            next: true,
+            prev: true,
+        }
+    }
+}
+
+pub fn dcel_write_dot<V>(
+    dcel: &Dcel<V>,
+    pos: impl Fn(&V) -> [f64; 2],
+    name: impl Fn(&V, &mut Formatter) -> fmt::Result,
+    f: &mut Formatter,
+    opt: DcelDotOptions,
+) -> fmt::Result {
+    writeln!(f, "digraph DCEL {{")?;
+    writeln!(f, "node [shape = circle]")?;
+    //writeln!(f, "nodesep = 1")?;
+
+    for shell in dcel.iter_bodies().flat_map(Lens::iter_shells) {
+        for vertex in shell.iter_vertices() {
+            let p = pos(vertex.data());
+
+            writeln!(
+                f,
+                "vertex_{} [label=\"{}\", pos=\"{},{}!\"]",
+                vertex.id(),
+                DisplayFn(|f| name(vertex.data(), f)),
+                p[0],
+                p[1]
+            )?;
+        }
+
+        for hedges in shell
+            .iter_edges()
+            .map(|x| x.half_edges())
+            .flat_map(|[he1, he2]| [[he1, he2], [he2, he1]])
+        {
+            let ids = hedges.map(Lens::id);
+            let vertices = hedges.map(|h| h.origin());
+            let points = vertices.map(|v| pos(v.data()));
+
+            let mut diff = [points[1][1] - points[0][1], points[1][0] - points[0][0]];
+
+            // let len = (diff[0] * diff[0] + diff[1] * diff[1]).sqrt();
+            diff[0] *= -0.075;
+            diff[1] *= 0.075;
+
+            let mid = [
+                (points[1][0] + points[0][0]) / 2.0 + diff[0],
+                (points[1][1] + points[0][1]) / 2.0 + diff[1],
+            ];
+
+            writeln!(
+                f,
+                "half_edge_{} [pos=\"{},{}!\", shape=point, width=0.01, height=0.01]",
+                ids[0], mid[0], mid[1]
+            )?;
+            writeln!(
+                f,
+                "vertex_{} -> half_edge_{} [arrowhead=none]",
+                vertices[0].id(),
+                ids[0]
+            )?;
+            writeln!(
+                f,
+                "half_edge_{} -> vertex_{} [label=\"{}\"]",
+                ids[0],
+                vertices[1].id(),
+                ids[0]
+            )?;
+
+            if opt.twin {
+                writeln!(
+                    f,
+                    "half_edge_{} -> half_edge_{} [color=\"red\"]",
+                    ids[0], ids[1]
+                )?;
+            }
+
+            if opt.next {
+                writeln!(
+                    f,
+                    "half_edge_{} -> half_edge_{} [color=\"green\"]",
+                    ids[0],
+                    hedges[0].next().id(),
+                )?;
+            }
+
+            if opt.prev {
+                writeln!(
+                    f,
+                    "half_edge_{} -> half_edge_{} [color=\"blue\"]",
+                    ids[0],
+                    hedges[0].prev().id(),
+                )?;
+            }
+        }
+    }
+
+    writeln!(f, "}}")
+}