Example: csg_primitives_demo
Figure 12.2 — Example: CSG Primitives Demo
Crate: cfd-suite (workspace root)
Run: cargo run --example csg_primitives_demo --features csg
Source: examples/csg_primitives_demo.rs
What This Example Demonstrates
Tessellates all supported CSG primitives (Cube, UV sphere, Cylinder, Cone) and validates each for volume accuracy, watertightness, Euler characteristic, and outward-normal orientation — no boolean operations, pure primitive baseline.
| Primitive | Expected volume | Validation |
|---|---|---|
| Cube (side=2) | 8 m³ | Signed-volume check |
| UV sphere (r=1) | 4π/3 ≈ 4.189 m³ | Signed-volume check |
| Cylinder (r, h) | π r² h | Watertight + Euler χ = 2 |
| Cone (r, h) | π r² h / 3 | Normal orientation |
Key Code Snippet
use cfd_mesh::{Cube, IndexedMesh, analyze_normals};
use cfd_mesh::application::watertight::check::check_watertight;
use cfd_mesh::domain::geometry::primitives::{Cone, Cylinder, PrimitiveMesh, UvSphere};
let mut mesh = Cube { origin: Point3r::new(-1.0,-1.0,-1.0),
width: 2.0, height: 2.0, depth: 2.0 }.build()?;
// Euler characteristic: V - E + F = 2 for any closed orientable surface
check_watertight(&mesh)?;Architecture
cfd-mesh (backed by the gaia Atlas crate) provides the topological substrate.
The IndexedMesh type owns vertices and cells; check_watertight and
analyze_normals operate through the AdjacencyGraph interface without
duplicating topology storage.