From 25485b518a111dc68c8d1ddb8544f44e7627632a Mon Sep 17 00:00:00 2001
From: Zack Brown <zack@zackbrown.co.uk>
Date: Sun, 11 Aug 2024 07:38:40 +0100
Subject: [PATCH] Do not automatically strip flat-shaded vertex normals (#127)

---
 Sources/Polygon.swift       |  4 ++--
 Tests/MeshExportTests.swift | 19 +++++++++++++------
 Tests/MeshTests.swift       |  7 -------
 Tests/SceneKitTests.swift   | 15 ++++-----------
 4 files changed, 19 insertions(+), 26 deletions(-)

diff --git a/Sources/Polygon.swift b/Sources/Polygon.swift
index 32f020d2..9325131c 100644
--- a/Sources/Polygon.swift
+++ b/Sources/Polygon.swift
@@ -161,9 +161,9 @@ public extension Polygon {
         vertices.contains(where: { $0.texcoord != .zero })
     }
 
-    /// A Boolean value that indicates whether the polygon includes vertex normals that differ from the face normal.
+    /// A Boolean value that indicates whether the polygon includes vertex normals.
     var hasVertexNormals: Bool {
-        vertices.contains(where: { !$0.normal.isEqual(to: plane.normal) && $0.normal != .zero })
+        vertices.contains(where: { $0.normal != .zero })
     }
 
     /// A Boolean value that indicates whether the polygon includes vertex colors.
diff --git a/Tests/MeshExportTests.swift b/Tests/MeshExportTests.swift
index a86a08e1..19dcec31 100644
--- a/Tests/MeshExportTests.swift
+++ b/Tests/MeshExportTests.swift
@@ -169,12 +169,19 @@ class MeshExportTests: XCTestCase {
         vt 1 0
         vt 0 0
 
-        f 1/1 2/2 3/3 4/4
-        f 5/1 6/2 7/3 8/4
-        f 7/1 4/2 3/3 8/4
-        f 5/1 2/2 1/3 6/4
-        f 6/1 1/2 4/3 7/4
-        f 2/1 5/2 8/3 3/4
+        vn 1 0 0
+        vn -1 0 0
+        vn 0 1 0
+        vn 0 -1 0
+        vn 0 0 1
+        vn 0 0 -1
+
+        f 1/1/1 2/2/1 3/3/1 4/4/1
+        f 5/1/2 6/2/2 7/3/2 8/4/2
+        f 7/1/3 4/2/3 3/3/3 8/4/3
+        f 5/1/4 2/2/4 1/3/4 6/4/4
+        f 6/1/5 1/2/5 4/3/5 7/4/5
+        f 2/1/6 5/2/6 8/3/6 3/4/6
         """)
     }
 
diff --git a/Tests/MeshTests.swift b/Tests/MeshTests.swift
index 1e9dcd7a..d6681d0d 100644
--- a/Tests/MeshTests.swift
+++ b/Tests/MeshTests.swift
@@ -335,11 +335,4 @@ class MeshTests: XCTestCase {
         let mesh = Mesh.cube().withoutTexcoords()
         XCTAssertFalse(mesh.hasTexcoords)
     }
-
-    func testMeshWithoutVertexNormals() {
-        let cube = Mesh.cube()
-        XCTAssertFalse(cube.hasVertexNormals)
-        let sphere = Mesh.sphere().smoothingNormals(forAnglesGreaterThan: .zero)
-        XCTAssertFalse(sphere.hasVertexNormals)
-    }
 }
diff --git a/Tests/SceneKitTests.swift b/Tests/SceneKitTests.swift
index d5edbe82..5cd02b52 100644
--- a/Tests/SceneKitTests.swift
+++ b/Tests/SceneKitTests.swift
@@ -111,15 +111,15 @@ class SceneKitTests: XCTestCase {
     func testExportCube() {
         let cube = Mesh.cube()
         let geometry = SCNGeometry(polygons: cube)
-        XCTAssertEqual(geometry.sources.count, 2)
-        XCTAssertEqual(geometry.sources.first?.vectorCount, 20)
+        XCTAssertEqual(geometry.sources.count, 3)
+        XCTAssertEqual(geometry.sources.first?.vectorCount, 24)
     }
 
     func testExportCubeWithoutTexcoords() {
         let cube = Mesh.cube().withoutTexcoords()
         let geometry = SCNGeometry(polygons: cube)
-        XCTAssertEqual(geometry.sources.count, 1)
-        XCTAssertEqual(geometry.sources.first?.vectorCount, 8)
+        XCTAssertEqual(geometry.sources.count, 2)
+        XCTAssertEqual(geometry.sources.first?.vectorCount, 24)
     }
 
     func testExportSphere() {
@@ -136,13 +136,6 @@ class SceneKitTests: XCTestCase {
         XCTAssertEqual(geometry.sources.first?.vectorCount, 151)
     }
 
-    func testExportSphereWithoutTexcoordsOrNormals() {
-        let sphere = Mesh.sphere().withoutTexcoords().smoothingNormals(forAnglesGreaterThan: .zero)
-        let geometry = SCNGeometry(polygons: sphere)
-        XCTAssertEqual(geometry.sources.count, 1)
-        XCTAssertEqual(geometry.sources.first?.vectorCount, 114)
-    }
-
     func testExportMeshWithColors() throws {
         let mesh = Mesh.lathe(.curve([
             .point(.unitY, color: .red),