Add Face and use it for top/bottom faces

This is one more (significant!) step in the direction of a real b-rep
representation.

experiments/2024-12-09/src/model.rs

@@ -1,11 +1,14 @@
+use itertools::Itertools;
+
 use crate::{
     geometry::{Shape, Sketch, Triangle},
     math::{Bivector, Plane, Point, Vector},
     storage::Store,
-    topology::Vertex,
+    topology::{Face, Vertex},
 };
 
 pub fn model(shape: &mut Shape) {
+    let mut faces = Store::<Face>::new();
     let mut surfaces = Store::<Plane>::new();
     let mut vertices = Store::<Vertex>::new();
     let mut triangles = Store::<Triangle>::new();
@@ -28,18 +31,18 @@ pub fn model(shape: &mut Shape) {
     let sketch =
         Sketch::from([[-0.5, -0.5], [0.5, -0.5], [0.5, 0.5], [-0.5, 0.5]]);
 
-    let (a, b, c, d, e, f, g, h) = shape
-        .extend_with(&mut vertices)
-        .add(bottom.point_from_local(sketch.points[0]))
-        .add(bottom.point_from_local(sketch.points[1]))
-        .add(bottom.point_from_local(sketch.points[2]))
-        .add(bottom.point_from_local(sketch.points[3]))
-        .add(top.point_from_local(sketch.points[0]))
-        .add(top.point_from_local(sketch.points[1]))
-        .add(top.point_from_local(sketch.points[2]))
-        .add(top.point_from_local(sketch.points[3]))
+    let [bottom, top] =
+        [bottom, top].map(|plane| Face::new(&sketch, plane, &mut vertices));
+
+    let (bottom, top) = shape
+        .extend_with(&mut faces)
+        .add(bottom)
+        .add(top)
         .get_added();
 
+    let [a, b, c, d] = bottom.vertices.iter().collect_array().unwrap();
+    let [e, f, g, h] = top.vertices.iter().collect_array().unwrap();
+
     let [a, b, c, d, e, f, g, h] =
         [a, b, c, d, e, f, g, h].map(|vertex| vertex.point);
 
@@ -52,9 +55,5 @@ pub fn model(shape: &mut Shape) {
         .add([d, c, f]) // front
         .add([d, f, e])
         .add([a, g, b]) // back
-        .add([a, h, g])
-        .add([d, a, c]) // bottom
-        .add([c, a, b])
-        .add([e, f, g]) // top
-        .add([e, g, h]);
+        .add([a, h, g]);
 }

experiments/2024-12-09/src/topology/face.rs

@@ -0,0 +1,90 @@
+use std::fmt;
+
+use spade::Triangulation;
+
+use crate::{
+    geometry::{AnyOp, Handle, Operation, Sketch, Triangle},
+    math::{Plane, Point},
+    storage::Store,
+};
+
+use super::Vertex;
+
+pub struct Face {
+    pub surface: Handle<Plane>,
+    pub vertices: Vec<Handle<Vertex>>,
+}
+
+impl Face {
+    pub fn new(
+        sketch: &Sketch,
+        surface: Handle<Plane>,
+        vertices: &mut Store<Vertex>,
+    ) -> Self {
+        let vertices = sketch
+            .points
+            .iter()
+            .copied()
+            .map(|point| {
+                let point = surface.point_from_local(point);
+                let vertex = Vertex::from(point);
+                vertices.insert(vertex)
+            })
+            .collect();
+
+        Self { surface, vertices }
+    }
+}
+
+impl fmt::Display for Face {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "face")
+    }
+}
+
+impl Operation for Face {
+    fn vertices(&self, vertices: &mut Vec<Vertex>) {
+        vertices.extend(self.vertices.iter().map(|vertex| **vertex));
+    }
+
+    fn triangles(&self, triangles: &mut Vec<Triangle>) {
+        // This is a placeholder implementation that only supports convex faces.
+
+        let mut triangulation =
+            spade::ConstrainedDelaunayTriangulation::<_>::new();
+
+        triangulation
+            .add_constraint_edges(
+                self.vertices.iter().map(|vertex| TriangulationPoint {
+                    point_surface: self.surface.project_point(vertex.point),
+                    point_vertex: vertex.point,
+                }),
+                true,
+            )
+            .unwrap();
+
+        triangles.extend(triangulation.inner_faces().map(|triangle| {
+            let vertices =
+                triangle.vertices().map(|vertex| vertex.data().point_vertex);
+            Triangle { vertices }
+        }));
+    }
+
+    fn children(&self) -> Vec<AnyOp> {
+        self.vertices.iter().map(|vertex| vertex.to_any()).collect()
+    }
+}
+
+struct TriangulationPoint {
+    point_surface: Point<2>,
+    point_vertex: Point<3>,
+}
+
+impl spade::HasPosition for TriangulationPoint {
+    type Scalar = f64;
+
+    fn position(&self) -> spade::Point2<Self::Scalar> {
+        let [x, y] = self.point_surface.coords.components.map(|s| s.value());
+        spade::Point2 { x, y }
+    }
+}

experiments/2024-12-09/src/topology/mod.rs

@@ -1,3 +1,4 @@
+mod face;
 mod vertex;
 
-pub use self::vertex::Vertex;
+pub use self::{face::Face, vertex::Vertex};