BulletNifLoader: Handle NiSkinPartition

Add NiSkinPartition recovery helper method

apps/openmw_test_suite/nif/node.hpp

@@ -53,6 +53,7 @@ namespace Nif::Testing
     {
         value.mData = NiSkinDataPtr(nullptr);
         value.mRoot = NiAVObjectPtr(nullptr);
+        value.mPartitions = NiSkinPartitionPtr(nullptr);
     }
 
     inline void init(NiTimeController& value)

components/nif/data.cpp

@@ -290,6 +290,17 @@ namespace Nif
         }
     }
 
+    const Nif::NiSkinPartition* NiSkinInstance::getPartitions() const
+    {
+        const Nif::NiSkinPartition* partitions = nullptr;
+        if (!mPartitions.empty())
+            partitions = mPartitions.getPtr();
+        else if (!mData.empty() && !mData->mPartitions.empty())
+            partitions = mData->mPartitions.getPtr();
+
+        return partitions;
+    }
+
     void BSDismemberSkinInstance::read(NIFStream* nif)
     {
         NiSkinInstance::read(nif);

components/nif/data.hpp

@@ -208,6 +208,8 @@ namespace Nif
 
         void read(NIFStream* nif) override;
         void post(Reader& nif) override;
+
+        const Nif::NiSkinPartition* getPartitions() const;
     };
 
     struct BSDismemberSkinInstance : public NiSkinInstance

components/nif/node.cpp

@@ -27,6 +27,37 @@ namespace
         mesh.preallocateIndices(static_cast<int>(data.mNumTriangles) * 3);
     }
 
+    void trianglesToBtTriangleMesh(btTriangleMesh& mesh, const std::vector<unsigned short>& triangles)
+    {
+        for (std::size_t i = 0; i < triangles.size(); i += 3)
+            mesh.addTriangleIndices(triangles[i + 0], triangles[i + 1], triangles[i + 2]);
+    }
+
+    void stripsToBtTriangleMesh(btTriangleMesh& mesh, const std::vector<std::vector<unsigned short>>& strips)
+    {
+        for (const auto& strip : strips)
+        {
+            if (strip.size() < 3)
+                continue;
+
+            unsigned short a;
+            unsigned short b = strip[0];
+            unsigned short c = strip[1];
+            for (size_t i = 2; i < strip.size(); i++)
+            {
+                a = b;
+                b = c;
+                c = strip[i];
+                if (a == b || b == c || a == c)
+                    continue;
+                if (i % 2 == 0)
+                    mesh.addTriangleIndices(a, b, c);
+                else
+                    mesh.addTriangleIndices(a, c, b);
+            }
+        }
+    }
+
 }
 
 namespace Nif
@@ -243,15 +274,33 @@ namespace Nif
         if (mData.empty() || mData->mVertices.empty())
             return nullptr;
 
+        std::vector<const std::vector<unsigned short>*> triangleLists;
+        std::vector<const std::vector<std::vector<unsigned short>>*> stripsLists;
         auto data = static_cast<const NiTriShapeData*>(mData.getPtr());
-        if (data->mNumTriangles == 0 || data->mTriangles.empty())
-            return nullptr;
+        const Nif::NiSkinPartition* partitions = nullptr;
+        if (!mSkin.empty())
+            partitions = mSkin->getPartitions();
 
+        if (partitions)
+        {
+            triangleLists.reserve(partitions->mPartitions.size());
+            stripsLists.reserve(partitions->mPartitions.size());
+            for (auto& partition : partitions->mPartitions)
+            {
+                triangleLists.push_back(&partition.mTrueTriangles);
+                stripsLists.push_back(&partition.mTrueStrips);
+            }
+        }
+        else if (data->mNumTriangles != 0)
+            triangleLists.push_back(&data->mTriangles);
+
+        // This makes a perhaps dangerous assumption that NiSkinPartition will never have more than 65536 triangles.
         auto mesh = std::make_unique<btTriangleMesh>();
         triBasedGeomToBtTriangleMesh(*mesh, *data);
-        const std::vector<unsigned short>& triangles = data->mTriangles;
-        for (std::size_t i = 0; i < triangles.size(); i += 3)
-            mesh->addTriangleIndices(triangles[i + 0], triangles[i + 1], triangles[i + 2]);
+        for (const auto triangles : triangleLists)
+            trianglesToBtTriangleMesh(*mesh, *triangles);
+        for (const auto strips : stripsLists)
+            stripsToBtTriangleMesh(*mesh, *strips);
 
         if (mesh->getNumTriangles() == 0)
             return nullptr;
@@ -267,33 +316,32 @@ namespace Nif
         if (mData.empty() || mData->mVertices.empty())
             return nullptr;
 
+        std::vector<const std::vector<unsigned short>*> triangleLists;
+        std::vector<const std::vector<std::vector<unsigned short>>*> stripsLists;
         auto data = static_cast<const NiTriStripsData*>(mData.getPtr());
-        if (data->mNumTriangles == 0 || data->mStrips.empty())
-            return nullptr;
+        const Nif::NiSkinPartition* partitions = nullptr;
+        if (!mSkin.empty())
+            partitions = mSkin->getPartitions();
 
-        auto mesh = std::make_unique<btTriangleMesh>();
-        triBasedGeomToBtTriangleMesh(*mesh, *data);
-        for (const std::vector<unsigned short>& strip : data->mStrips)
+        if (partitions)
         {
-            if (strip.size() < 3)
-                continue;
-
-            unsigned short a;
-            unsigned short b = strip[0];
-            unsigned short c = strip[1];
-            for (size_t i = 2; i < strip.size(); i++)
+            triangleLists.reserve(partitions->mPartitions.size());
+            stripsLists.reserve(partitions->mPartitions.size());
+            for (auto& partition : partitions->mPartitions)
             {
-                a = b;
-                b = c;
-                c = strip[i];
-                if (a == b || b == c || a == c)
-                    continue;
-                if (i % 2 == 0)
-                    mesh->addTriangleIndices(a, b, c);
-                else
-                    mesh->addTriangleIndices(a, c, b);
+                triangleLists.push_back(&partition.mTrueTriangles);
+                stripsLists.push_back(&partition.mTrueStrips);
             }
         }
+        else if (data->mNumTriangles != 0)
+            stripsLists.push_back(&data->mStrips);
+
+        auto mesh = std::make_unique<btTriangleMesh>();
+        triBasedGeomToBtTriangleMesh(*mesh, *data);
+        for (const auto triangles : triangleLists)
+            trianglesToBtTriangleMesh(*mesh, *triangles);
+        for (const auto strips : stripsLists)
+            stripsToBtTriangleMesh(*mesh, *strips);
 
         if (mesh->getNumTriangles() == 0)
             return nullptr;

components/nifbullet/bulletnifloader.cpp

@@ -277,7 +277,6 @@ namespace NifBullet
 
         if (!niGeometry.mSkin.empty())
             args.mAnimated = false;
-        // TODO: handle NiSkinPartition
 
         std::unique_ptr<btCollisionShape> childShape = niGeometry.getCollisionShape();
         if (childShape == nullptr)

components/nifosg/nifloader.cpp

@@ -1381,17 +1381,7 @@ namespace NifOsg
             if (!niGeometry->mSkin.empty())
             {
                 const Nif::NiSkinInstance* skin = niGeometry->mSkin.getPtr();
-                const Nif::NiSkinData* data = nullptr;
-                const Nif::NiSkinPartition* partitions = nullptr;
-                if (!skin->mData.empty())
-                {
-                    data = skin->mData.getPtr();
-                    if (!data->mPartitions.empty())
-                        partitions = data->mPartitions.getPtr();
-                }
-                if (!partitions && !skin->mPartitions.empty())
-                    partitions = skin->mPartitions.getPtr();
-
+                const Nif::NiSkinPartition* partitions = skin->getPartitions();
                 hasPartitions = partitions != nullptr;
                 if (hasPartitions)
                 {