Merge pull request #435 from hannobraun/triangulate

Add triangulation test suite

fj-kernel/src/algorithms/triangulation.rs

@@ -212,3 +212,92 @@ impl HasPosition for geometry::Point<2> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use fj_debug::DebugInfo;
+    use fj_math::{Scalar, Triangle};
+
+    use crate::{geometry::Surface, shape::Shape, topology::Face};
+
+    #[test]
+    fn simple() -> anyhow::Result<()> {
+        let mut shape = Shape::new();
+
+        let a = [0., 0., 0.];
+        let b = [2., 0., 0.];
+        let c = [2., 2., 0.];
+        let d = [0., 1., 0.];
+
+        Face::builder(Surface::x_y_plane(), &mut shape)
+            .with_exterior_polygon([a, b, c, d])
+            .build()?;
+
+        let triangles = triangulate(shape);
+        assert!(triangles.contains([a, b, d]));
+        assert!(triangles.contains([b, c, d]));
+        assert!(!triangles.contains([a, b, c]));
+        assert!(!triangles.contains([a, c, d]));
+
+        Ok(())
+    }
+
+    #[test]
+    fn simple_hole() -> anyhow::Result<()> {
+        let mut shape = Shape::new();
+
+        let a = [0., 0., 0.];
+        let b = [4., 0., 0.];
+        let c = [4., 4., 0.];
+        let d = [0., 4., 0.];
+
+        let e = [1., 1., 0.];
+        let f = [3., 1., 0.];
+        let g = [3., 3., 0.];
+        let h = [1., 2., 0.];
+
+        Face::builder(Surface::x_y_plane(), &mut shape)
+            .with_exterior_polygon([a, b, c, d])
+            .with_interior_polygon([e, f, g, h])
+            .build()?;
+
+        let triangles = triangulate(shape);
+
+        // Should contain some triangles from the polygon. Don't need to test
+        // them all.
+        assert!(triangles.contains([a, e, h]));
+        assert!(triangles.contains([a, d, h]));
+
+        // Shouldn't contain any possible triangle from the hole.
+        assert!(!triangles.contains([e, f, g]));
+        assert!(!triangles.contains([e, g, h]));
+        assert!(!triangles.contains([e, f, h]));
+        assert!(!triangles.contains([f, g, h]));
+
+        Ok(())
+    }
+
+    fn triangulate(shape: Shape) -> Triangles {
+        let tolerance = Scalar::ONE;
+
+        let mut triangles = Vec::new();
+        let mut debug_info = DebugInfo::new();
+
+        super::triangulate(shape, tolerance, &mut triangles, &mut debug_info);
+
+        for triangle in &mut triangles {
+            *triangle = triangle.normalize();
+        }
+
+        Triangles(triangles)
+    }
+
+    struct Triangles(Vec<Triangle<3>>);
+
+    impl Triangles {
+        fn contains(&self, triangle: impl Into<Triangle<3>>) -> bool {
+            let triangle = triangle.into().normalize();
+            self.0.contains(&triangle)
+        }
+    }
+}