From a1d820dae390d4fb4e82a5e54d1ebe20cad588bc Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Thu, 4 Apr 2024 10:59:26 +0200
Subject: [PATCH 1/3] Panic, if user tries to redefine basis planes

---
 crates/fj-core/src/geometry/geometry.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/crates/fj-core/src/geometry/geometry.rs b/crates/fj-core/src/geometry/geometry.rs
index 10999dd99..783ff7dc1 100644
--- a/crates/fj-core/src/geometry/geometry.rs
+++ b/crates/fj-core/src/geometry/geometry.rs
@@ -69,6 +69,14 @@ impl Geometry {
         surface: Handle<Surface>,
         geometry: SurfaceGeom,
     ) {
+        if self.surface.contains_key(&surface)
+            && (surface == self.xy_plane
+                || surface == self.xz_plane
+                || surface == self.yz_plane)
+        {
+            panic!("Attempting to redefine basis plane.");
+        }
+
         self.surface.insert(surface, geometry);
     }
 

From 421a5b67e60a8db0bce312df6fb718fc2ee6895d Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Thu, 4 Apr 2024 10:59:50 +0200
Subject: [PATCH 2/3] Update formatting

---
 crates/fj-core/src/layers/geometry.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/fj-core/src/layers/geometry.rs b/crates/fj-core/src/layers/geometry.rs
index 1bfeaf893..f3659349b 100644
--- a/crates/fj-core/src/layers/geometry.rs
+++ b/crates/fj-core/src/layers/geometry.rs
@@ -25,7 +25,7 @@ impl Layer<Geometry> {
         );
     }
 
-    /// Define the geometry of the provided surface
+    /// # Define the geometry of the provided surface
     pub fn define_surface(
         &mut self,
         surface: Handle<Surface>,

From 55b6296990b10ff06bf90a8118ae25c9dc748256 Mon Sep 17 00:00:00 2001
From: Hanno Braun <hanno@braun-odw.eu>
Date: Thu, 4 Apr 2024 11:01:01 +0200
Subject: [PATCH 3/3] Update documentation of `define_surface`

---
 crates/fj-core/src/layers/geometry.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/crates/fj-core/src/layers/geometry.rs b/crates/fj-core/src/layers/geometry.rs
index f3659349b..b23aa5cd2 100644
--- a/crates/fj-core/src/layers/geometry.rs
+++ b/crates/fj-core/src/layers/geometry.rs
@@ -26,6 +26,11 @@ impl Layer<Geometry> {
     }
 
     /// # Define the geometry of the provided surface
+    ///
+    /// ## Panics
+    ///
+    /// Panics, if the surface is a special pre-defined plane, like the basis
+    /// planes (xy-, xz-, or yz-plane).
     pub fn define_surface(
         &mut self,
         surface: Handle<Surface>,