Shape inspection by torusJKL · Pull Request #228 · bschwind/opencascade-rs

torusJKL · 2026-06-29T12:30:43Z

This PR adds inspection/query capabilities across shape types.
I included all the different types in one PR since they are all about inspection of properties but I can split them based on shape type if that is preferable.

The following can be inspected:

Solid

volume(), center_of_mass(), surface_area()

Face / Surface

SurfaceType enum with face type detection
Surface geometry: periodicity, continuity, degrees, knots, poles, evaluation (d0, d1, d2)

Edge

length(), tangent_at(), arc_center(), radius()

Wire

length(), is_closed()

Shape

center_of_mass()

…bindings

bschwind · 2026-07-01T08:23:46Z

@torusJKL Thanks for another PR, I'll try to get to reviewing this soon, it'll take a bit of time as it's a larger PR.

bschwind

Thanks for being patient! In general the changes are good but there are some improvements we can make to reduce the C++ boilerplate, and remove things like runtime string matching.

bschwind · 2026-07-26T06:43:07Z

      new opencascade::handle<Poly_Triangulation>(BRep_Tool::Triangulation(face, location)));
 }
+
+inline bool BRep_Tool_IsClosed(const TopoDS_Wire &wire) { return BRep_Tool::IsClosed(wire); }


It's slightly clumsier in this case (because you have to cast a Wire to a Shape), but you can bind to static class functions like this:

#[Self = "BRep_Tool"] pub fn IsClosed(shape: &TopoDS_Shape) -> bool;

Just noting that as an option though, this code is fine as-is.

bschwind · 2026-08-20T07:08:58Z

+    let edge = Edge::segment(DVec3::new(0.0, 0.0, 0.0), DVec3::new(10.0, 0.0, 0.0));
+    let tangent = edge.tangent_at(0.5, PositionMode::Parameter);
+    let expected = DVec3::new(1.0, 0.0, 0.0);
+    assert!(tangent.distance_squared(expected) < 1e-6, "expected {expected:?}, got {tangent:?}");


A dot product being approximately equal to 1.0 would probably be a more appropriate check here.

bschwind · 2026-08-20T07:12:19Z

+fn approx_equal(a: f64, b: f64) {
+    let diff = (a - b).abs();
+    let rel = diff / b.abs().max(1e-12);
+    assert!(rel < 1e-4 || diff < 1e-6, "expected {b}, got {a} (diff={diff}, rel={rel})");
+}


Let's move this into a shared test module that edge_inspection can also use.

bschwind · 2026-08-20T07:20:36Z

+inline void BRepAdaptor_Curve_D1(const BRepAdaptor_Curve &curve, const Standard_Real U, gp_Pnt &P, gp_Vec &V1) {
+  curve.D1(U, P, V1);
+}


This one can fortunately be auto-bound

Suggested change

inline void BRepAdaptor_Curve_D1(const BRepAdaptor_Curve &curve, const Standard_Real U, gp_Pnt &P, gp_Vec &V1) {

curve.D1(U, P, V1);

}

In b_rep_adaptor.rs, you can write:

#[cxx_name = "D1"] pub fn d1(self: &BRepAdaptor_Curve, u: f64, point: Pin<&mut gp_Pnt>, vec: Pin<&mut gp_Vec>);

And then in edge.rs, it can be called like so:

curve.d1(param, point.pin_mut(), vec.pin_mut());

In general I try to avoid as much C++ code as possible in the wrappers. For things like wrapping code in unique_ptr, or handles, it's hard to avoid, but for simpler types you can usually get cxx-rs to automatically bind things.

bschwind · 2026-08-20T07:24:59Z

+        pub fn BRepAdaptor_Curve_D1(
+            curve: &BRepAdaptor_Curve,
+            u: f64,
+            point: Pin<&mut gp_Pnt>,
+            vec: Pin<&mut gp_Vec>,
+        );


As noted in another comment, this can become:

#[cxx_name = "D1"] pub fn d1(self: &BRepAdaptor_Curve, u: f64, point: Pin<&mut gp_Pnt>, vec: Pin<&mut gp_Vec>);

bschwind · 2026-08-21T01:59:26Z

+        let param = match mode {
+            PositionMode::Parameter => position,
+            PositionMode::Length => {
+                let first = curve.FirstParameter();
+                let last = curve.LastParameter();
+                first + position * (last - first)
+            },
+        };


Do we really want PositionMode at all here? The API is confusing, and I don't see any tests demonstrating what it's useful for. It interpolates between the first and last parameter of the curve, but when would you use that?

bschwind · 2026-08-21T02:01:32Z

+inline double HandleGeomSphericalSurface_Radius(const Handle_Geom_SphericalSurface &sphere) { return sphere->Radius(); }
+
+inline const gp_Ax3 &HandleGeomSphericalSurface_Position(const Handle_Geom_SphericalSurface &sphere) {
+  return sphere->Position();
+}


Can these be auto-bound?

bschwind · 2026-08-21T02:01:59Z

+inline double HandleGeomConicalSurface_RefRadius(const Handle_Geom_ConicalSurface &cone) { return cone->RefRadius(); }
+
+inline double HandleGeomConicalSurface_SemiAngle(const Handle_Geom_ConicalSurface &cone) { return cone->SemiAngle(); }
+
+inline const gp_Ax3 &HandleGeomConicalSurface_Position(const Handle_Geom_ConicalSurface &cone) {
+  return cone->Position();
+}


Same here, let's try to auto-bind these.

bschwind · 2026-08-21T02:02:09Z

+inline double HandleGeomToroidalSurface_MajorRadius(const Handle_Geom_ToroidalSurface &torus) {
+  return torus->MajorRadius();
+}
+
+inline double HandleGeomToroidalSurface_MinorRadius(const Handle_Geom_ToroidalSurface &torus) {
+  return torus->MinorRadius();
+}
+
+inline const gp_Ax3 &HandleGeomToroidalSurface_Position(const Handle_Geom_ToroidalSurface &torus) {
+  return torus->Position();
+}


bschwind · 2026-08-21T02:04:46Z

+        pub fn new_HandleGeomCylindricalSurface_from_HandleGeomSurface(
+            geom_surface_handle: &Handle_Geom_Surface,
+        ) -> UniquePtr<Handle_Geom_CylindricalSurface>;
+        pub fn HandleGeomCylindricalSurface_Radius(cyl: &Handle_Geom_CylindricalSurface) -> f64;
+        pub fn HandleGeomCylindricalSurface_Position(
+            cyl: &Handle_Geom_CylindricalSurface,
+        ) -> &gp_Ax3;


Sorry the code for Handles is pretty atrocious right now, I need to find a better way to abstract this, maybe a macro or something.

torusJKL added 8 commits June 28, 2026 16:32

Add volume, center_of_mass, surface_area to Solid

4232ce4

Add SurfaceType enum and face surface type detection

bf6051d

Add edge inspection: length, tangent_at, arc_center, radius with FFI …

50833e6

…bindings

Add Wire::length() and Wire::is_closed()

cca8490

Add Shape::center_of_mass() with dispatch and tests

b3151cc

Add surface geometry query methods to Face and Surface

eed0a58

Merge branch 'main' into shape-inspection

f77d40a

Fix clang formatting

fedea44

bschwind reviewed Aug 21, 2026

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Shape inspection - #228

Shape inspection#228
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torusJKL:shape-inspection

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	inline void BRepAdaptor_Curve_D1(const BRepAdaptor_Curve &curve, const Standard_Real U, gp_Pnt &P, gp_Vec &V1) {
	curve.D1(U, P, V1);
	}

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torusJKL commented Jun 29, 2026

Solid

Face / Surface

Edge

Wire

Shape

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bschwind commented Jul 1, 2026

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