From 251b42ad0611824b12bb5df36f3512b6bdebd4f0 Mon Sep 17 00:00:00 2001
From: Viktor Kovacs <viktorkovacs@gmail.com>
Date: Mon, 24 May 2021 20:40:34 +0200
Subject: [PATCH] Do not calculate same normal multiple times so triangulation
 won't effect curved normal calculation.

---
 source/model/modelfinalization.js | 30 ++++++++++++++++++++--------
 test/tests/model_test.js          | 33 +++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/source/model/modelfinalization.js b/source/model/modelfinalization.js
index ac62b10..0306bd5 100644
--- a/source/model/modelfinalization.js
+++ b/source/model/modelfinalization.js
@@ -6,22 +6,36 @@ OV.FinalizeModel = function (model, getDefaultMaterial)
         {
             function AddAverageNormal (mesh, triangle, vertexIndex, triangleNormals, vertexToTriangles)
             {
-                // TODO: do not calculate the same normal multiple times
-                
-                let averageNormal = new OV.Coord3D (0.0, 0.0, 0.0);
-                let averageCount = 0;
-                
+                function IsNormalInArray (array, normal)
+                {
+                    for (let i = 0; i < array.length; i++) {
+                        let current = array[i];
+                        if (OV.CoordIsEqual3D (current, normal)) {
+                            return true;
+                        }                        
+                    }
+                    return false;
+                }
+
+                let averageNormals = [];
                 let neigTriangles = vertexToTriangles[vertexIndex];
                 for (let i = 0; i < neigTriangles.length; i++) {
                     let neigIndex = neigTriangles[i];
                     let neigTriangle = mesh.GetTriangle (neigIndex);
                     if (triangle.curve === neigTriangle.curve) {
-                        averageNormal = OV.AddCoord3D (averageNormal, triangleNormals[neigIndex]);
-                        averageCount = averageCount + 1;
+                        let triangleNormal = triangleNormals[neigIndex];
+                        if (!IsNormalInArray (averageNormals, triangleNormal)) {
+                            averageNormals.push (triangleNormal);
+                        }
                     }
                 }
+
+                let averageNormal = new OV.Coord3D (0.0, 0.0, 0.0);
+                for (let i = 0; i < averageNormals.length; i++) {
+                    averageNormal = OV.AddCoord3D (averageNormal, averageNormals[i]);
+                }
                 
-                averageNormal.MultiplyScalar (1.0 / averageCount);
+                averageNormal.MultiplyScalar (1.0 / averageNormals.length);
                 averageNormal.Normalize ();
                 return mesh.AddNormal (averageNormal);
             }
diff --git a/test/tests/model_test.js b/test/tests/model_test.js
index 5031851..6189302 100644
--- a/test/tests/model_test.js
+++ b/test/tests/model_test.js
@@ -149,6 +149,39 @@ describe ('Model Finalization', function() {
         assert.strictEqual (normal.y, -0.7071067811865475);
         assert.strictEqual (normal.z, 0.7071067811865475);
     });
+
+    it ('Calculate Curved Normal 2', function () {
+        var mesh = new OV.Mesh ();
+        var v0 = mesh.AddVertex (new OV.Coord3D (0.0, 0.0, 0.0));
+        var v1 = mesh.AddVertex (new OV.Coord3D (1.0, 0.0, 0.0));
+        var v2 = mesh.AddVertex (new OV.Coord3D (1.0, 1.0, 0.0));
+        var v3 = mesh.AddVertex (new OV.Coord3D (0.0, 0.0, -1.0));
+        var v4 = mesh.AddVertex (new OV.Coord3D (0.0, 1.0, 0.0));
+
+        var triangle1 = new OV.Triangle (v0, v1, v2);
+        triangle1.curve = 1;
+        var triangle2 = new OV.Triangle (v0, v2, v4);
+        triangle2.curve = 1;
+        var triangle3 = new OV.Triangle (v0, v3, v1);
+        triangle3.curve = 1;
+
+        mesh.AddTriangle (triangle1);
+        mesh.AddTriangle (triangle2);
+        mesh.AddTriangle (triangle3);
+
+        var model = new OV.Model ()
+        var meshIndex = model.AddMesh (mesh);
+
+        OV.FinalizeModel (model, function () { new OV.Material () });
+        
+        var theMesh = model.GetMesh (meshIndex);
+        assert.strictEqual (theMesh.NormalCount (), 9);
+        
+        var normal = theMesh.GetNormal (0);
+        assert.strictEqual (normal.x, 0.0);
+        assert.strictEqual (normal.y, -0.7071067811865475);
+        assert.strictEqual (normal.z, 0.7071067811865475);
+    });    
 });
 
 describe ('Color Conversion', function() {