PERF-2 P1.2: the overlap map's cell classification skips the point location for background cells outside the patch's node bounding box (no patch cell can contain them and the body lies inside the patch: Active, the class the search returns); PatchMesh::bounding_box

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YJPeT6WA2e7YvAnS875AHL

crates/specialized/rtx-cfd/src/mesh/patch_mesh.rs

@@ -173,6 +173,23 @@ impl PatchMesh {
         k * (self.ns + 1) + i
     }
     /// Node coordinates.
+    /// `[x_min, x_max, y_min, y_max]` over the nodes.
+    pub fn bounding_box(&self) -> [f64; 4] {
+        let (mut b, mut first) = ([0.0; 4], true);
+        for (&x, &y) in self.x.iter().zip(&self.y) {
+            if first {
+                b = [x, x, y, y];
+                first = false;
+            } else {
+                b[0] = b[0].min(x);
+                b[1] = b[1].max(x);
+                b[2] = b[2].min(y);
+                b[3] = b[3].max(y);
+            }
+        }
+        b
+    }
+
     pub fn node_xy(&self, n: usize) -> [f64; 2] {
         [self.x[n], self.y[n]]
     }

crates/specialized/rtx-cfd/src/solvers/incompressible/overset/overlap.rs

@@ -162,13 +162,20 @@ impl OverlapMap {
         let primal = QuadIndex::primal(patch);
         let body = body_polygon(patch);
 
-        // 1. Cells.
+        // 1. Cells. A centre outside the patch's node bounding box lies in
+        //    no patch cell and outside the body (which the patch encloses):
+        //    Active without a point location (PERF-2 P1.2, the same class
+        //    the search would return).
+        let bbox = patch.bounding_box();
         let mut class = vec![CellClass::Active; nx * ny];
         let mut hole_cells = 0;
         for j in 0..ny {
             for i in 0..nx {
                 let x = (i as f64 + 0.5) * dx;
                 let y = (j as f64 + 0.5) * dy;
+                if x < bbox[0] || x > bbox[1] || y < bbox[2] || y > bbox[3] {
+                    continue;
+                }
                 let in_hole = match primal.locate(patch, x, y) {
                     Some(c) => patch.cell_ki(c).0 <= hole_row_max,
                     None => body