Add builder API for Vertex

crates/fj-kernel/src/builder/edge.rs

@@ -18,7 +18,7 @@ impl HalfEdgeBuilder {
         Self { surface }
     }
 
-    /// Create a circle from the given radius
+    /// Build a circle from the given radius
     pub fn circle_from_radius(&self, radius: Scalar) -> HalfEdge {
         let curve = {
             let local = CurveKind::Circle(Circle::new(
@@ -68,7 +68,7 @@ impl HalfEdgeBuilder {
         HalfEdge::from_curve_and_vertices(curve, vertices)
     }
 
-    /// Create a line segment from two points
+    /// Build a line segment from two points
     pub fn line_segment_from_points(
         &self,
         points: [impl Into<Point<2>>; 2],

crates/fj-kernel/src/builder/mod.rs

@@ -7,6 +7,7 @@ mod face;
 mod shell;
 mod sketch;
 mod solid;
+mod vertex;
 
 pub use self::{
     curve::{CurveBuilder, GlobalCurveBuilder},
@@ -16,4 +17,5 @@ pub use self::{
     shell::ShellBuilder,
     sketch::SketchBuilder,
     solid::SolidBuilder,
+    vertex::VertexBuilder,
 };

crates/fj-kernel/src/builder/vertex.rs

@@ -0,0 +1,37 @@
+use fj_math::Point;
+
+use crate::objects::{Curve, GlobalVertex, SurfaceVertex, Vertex};
+
+/// API for building a [`Vertex`]
+pub struct VertexBuilder {
+    curve: Curve,
+}
+
+impl VertexBuilder {
+    /// Construct a new instance of `VertexBuilder`
+    ///
+    /// Also see [`Vertex::build`].
+    pub fn new(curve: Curve) -> Self {
+        Self { curve }
+    }
+
+    /// Build a vertex from a curve position
+    pub fn from_point(&self, point: impl Into<Point<1>>) -> Vertex {
+        let point = point.into();
+        let &surface = self.curve.surface();
+
+        let global_form = GlobalVertex::from_position(
+            self.curve
+                .global_form()
+                .kind()
+                .point_from_curve_coords(point),
+        );
+        let surface_form = SurfaceVertex::new(
+            self.curve.kind().point_from_curve_coords(point),
+            surface,
+            global_form,
+        );
+
+        Vertex::new([0.], self.curve, surface_form, global_form)
+    }
+}

crates/fj-kernel/src/objects/vertex.rs

@@ -1,6 +1,8 @@
 use fj_math::Point;
 use pretty_assertions::assert_eq;
 
+use crate::builder::VertexBuilder;
+
 use super::{Curve, Surface};
 
 /// A vertex
@@ -17,6 +19,11 @@ pub struct Vertex {
 }
 
 impl Vertex {
+    /// Build a vertex using [`VertexBuilder`]
+    pub fn build(curve: Curve) -> VertexBuilder {
+        VertexBuilder::new(curve)
+    }
+
     /// Construct an instance of `Vertex`
     ///
     /// Panics, if `curve` and `surface_form` are not defined on the same