Add CurveGeom

crates/fj-core/src/geometry/curve.rs

@@ -0,0 +1,36 @@
+use crate::{storage::Handle, topology::Surface};
+
+use super::SurfacePath;
+
+/// The geometric definition of a curve
+#[derive(Clone)]
+pub struct CurveGeom {
+    /// # The redundant local definitions of the curve geometry
+    ///
+    /// ## Implementation Note
+    ///
+    /// Having multiple redundant definitions is undesirable. However, we can't
+    /// just use one global definition in 3D, as we need the local 2D
+    /// definitions to approximate and triangulate curves, and we currently
+    /// don't have the tools to project a global definition into a local
+    /// context.
+    ///
+    /// Eventually, it should be possible to define the geometry of a curve
+    /// once, either locally or globally, and then convert that single
+    /// definition into (other) local contexts, as needed. There currently is no
+    /// issue to track that specifically, but there is the following issue,
+    /// which is a prerequisite for making the required tooling practical:
+    ///
+    /// <https://github.com/hannobraun/fornjot/issues/2118>
+    pub definitions: Vec<LocalCurveGeom>,
+}
+
+/// The geometric definition of a curve in 2D surface coordinates
+#[derive(Clone)]
+pub struct LocalCurveGeom {
+    /// The path that defines the curve on its surface
+    pub path: SurfacePath,
+
+    /// The surface that the curve is defined on
+    pub surface: Handle<Surface>,
+}

crates/fj-core/src/geometry/mod.rs

@@ -1,6 +1,7 @@
 //! Types that are tied to objects, but aren't objects themselves
 
 mod boundary;
+mod curve;
 mod geometry;
 mod half_edge;
 mod path;
@@ -8,6 +9,7 @@ mod surface;
 
 pub use self::{
     boundary::{CurveBoundary, CurveBoundaryElement},
+    curve::{CurveGeom, LocalCurveGeom},
     geometry::Geometry,
     half_edge::HalfEdgeGeom,
     path::{GlobalPath, SurfacePath},