From e18254ec29f844c5e1b82282c820735df31d29ee Mon Sep 17 00:00:00 2001
From: Dynamitos <dynamitos15@gmail.com>
Date: Sun, 24 Dec 2023 23:45:43 +0100
Subject: [PATCH] adding vertex deduplication flag to mesh import

---
 src/Editor/Asset/MeshLoader.cpp |   4 +-
 src/Engine/Graphics/Meshlet.cpp | 139 +-------------------------------
 2 files changed, 3 insertions(+), 140 deletions(-)

diff --git a/src/Editor/Asset/MeshLoader.cpp b/src/Editor/Asset/MeshLoader.cpp
index 92dad4b..0069cc8 100644
--- a/src/Editor/Asset/MeshLoader.cpp
+++ b/src/Editor/Asset/MeshLoader.cpp
@@ -329,7 +329,7 @@ void MeshLoader::import(MeshImportArgs args, PMeshAsset meshAsset)
     meshAsset->setStatus(Asset::Status::Loading);
     Assimp::Importer importer;
     importer.ReadFile(args.filePath.string().c_str(), (uint32)(
-        aiProcess_ImproveCacheLocality |
+        aiProcess_JoinIdenticalVertices |
         aiProcess_FlipUVs |
         aiProcess_Triangulate |
         aiProcess_SortByPType |
@@ -337,7 +337,7 @@ void MeshLoader::import(MeshImportArgs args, PMeshAsset meshAsset)
         aiProcess_GenSmoothNormals |
         aiProcess_GenUVCoords |
         aiProcess_FindDegenerates));
-    const aiScene *scene = importer.ApplyPostProcessing(aiProcess_CalcTangentSpace);
+    const aiScene *scene = importer.ApplyPostProcessing(aiProcess_CalcTangentSpace | aiProcess_ImproveCacheLocality);
     
     Array<PMaterialInstanceAsset> globalMaterials(scene->mNumMaterials);
     loadTextures(scene, args.filePath.parent_path(), args.importPath);
diff --git a/src/Engine/Graphics/Meshlet.cpp b/src/Engine/Graphics/Meshlet.cpp
index 6ff5420..a46cefb 100644
--- a/src/Engine/Graphics/Meshlet.cpp
+++ b/src/Engine/Graphics/Meshlet.cpp
@@ -5,143 +5,6 @@
 
 using namespace Seele;
 
-// Tipsy algorithm by Sanders 2007
-struct Triangle
-{
-    bool emitted = false;
-    StaticArray<uint32, 3> indices;
-};
-
-Map<uint32, List<Triangle>> buildAdjacency(const Array<uint32>& indices)
-{
-    Map<uint32, List<Triangle>> result;
-    for (uint32 i = 0; i < indices.size(); i += 3)
-    {
-        result[indices[i + 0]].add(Triangle{
-            .emitted = false,
-            .indices = {
-                indices[i + 0],
-                indices[i + 1],
-                indices[i + 2],
-            }
-            });
-        result[indices[i + 1]].add(Triangle{
-            .emitted = false,
-            .indices = {
-                indices[i + 0],
-                indices[i + 1],
-                indices[i + 2],
-            }
-            });
-        result[indices[i + 2]].add(Triangle{
-            .emitted = false,
-            .indices = {
-                indices[i + 0],
-                indices[i + 1],
-                indices[i + 2],
-            }
-            });
-    }
-    return result;
-}
-
-Map<uint32, uint32> getTriangleCounts(Map<uint32, List<Triangle>>& adjacency)
-{
-    Map<uint32, uint32> result;
-    for (const auto& [index, list] : adjacency)
-    {
-        result[index] = list.size();
-    }
-    return result;
-}
-
-int32 skipDeadEnd(Map<uint32, uint32>& L, Array<uint32>& D, const Array<uint32>& indices, uint32& i, uint32 vertexCount)
-{
-    while (!D.empty())
-    {
-        uint32 d = D.back();
-        D.pop();
-        if (L[d] > 0)
-        {
-            return d;
-        }
-    }
-    while (i < vertexCount)
-    {
-        i++;
-        if (L[i] > 0)
-        {
-            return i;
-        }
-    }
-    return -1;
-}
-
-uint32 getNextVertex(const Array<uint32>& indices, uint32& i, uint32 cacheSize, Set<uint32> N, const Array<uint32>& C, uint32 s, Map<uint32, uint32>& L, Array<uint32>& D, uint32 vertexCount)
-{
-    int32 n = -1;
-    int32 p = -1;
-    int32 m = 0;
-    for (uint32 v : N)
-    {
-        if (L[v] > 0)
-        {
-            p = 0;
-            if (s - C[v] + 2 * L[v] <= cacheSize)
-            {
-                p = s - C[v];
-            }
-            if (p > m)
-            {
-                m = p;
-                n = v;
-            }
-        }
-    }
-    if (n == -1)
-    {
-        n = skipDeadEnd(L, D, indices, i, vertexCount);
-    }
-    return n;
-}
-
-Array<uint32> tipsify(const Array<Vector>& positions, const Array<uint32>& indices, uint32 cacheSize)
-{
-    auto A = buildAdjacency(indices);
-    auto L = getTriangleCounts(A);
-    auto C = Array<uint32>(positions.size(), 0);
-    auto D = Array<uint32>();
-    Array<uint32> output;
-    int32 f = 0;
-    uint32 s = cacheSize + 1, i = 1;
-    while (f >= 0)
-    {
-        auto N = Set<uint32>();
-        for (Triangle t : A[f])
-        {
-            if (!t.emitted)
-            {
-                for (uint32 v : t.indices)
-                {
-                    output.add(v);
-                    D.add(v);
-                    N.insert(v);
-                    L[v] = L[v] - 1;
-                    if (s - C[v] > cacheSize)
-                    {
-                        C[v] = s;
-                        s = s + 1;
-                    }
-                }
-                t.emitted = true;
-            }
-        }
-        f = getNextVertex(indices, i, cacheSize, std::move(N), C, s, L, D, positions.size());
-    }
-    return output;
-}
-
-
 void Meshlet::build(const Array<Vector>& positions, const Array<uint32>& indices, Array<Meshlet>& meshlets)
 {
     Meshlet current = {
@@ -180,7 +43,7 @@ void Meshlet::build(const Array<Vector>& positions, const Array<uint32>& indices
         int f2 = findIndex(indices[faceIndex * 3 + 1]);
         int f3 = findIndex(indices[faceIndex * 3 + 2]);
 
-        if (f1 == -1 || f2 == -1 || f1 == -1)
+        if (f1 == -1 || f2 == -1 || f3 == -1)
         {
             completeMeshlet();
             f1 = findIndex(indices[faceIndex * 3 + 0]);