From 3f252eab5d3cb7986a5393f72c7149e5db9b5689 Mon Sep 17 00:00:00 2001
From: Alexei Kotov <alexdobrohotov@yandex.ru>
Date: Sun, 16 Jul 2023 03:06:00 +0300
Subject: [PATCH] Copy triangle data from NiSkinPartition

---
 components/nif/data.cpp                  |  33 +++++++
 components/nif/data.hpp                  |   3 +
 components/nifbullet/bulletnifloader.cpp |   1 +
 components/nifosg/nifloader.cpp          | 106 ++++++++++++++++-------
 4 files changed, 110 insertions(+), 33 deletions(-)

diff --git a/components/nif/data.cpp b/components/nif/data.cpp
index cba34d9a6d..018e9fc603 100644
--- a/components/nif/data.cpp
+++ b/components/nif/data.cpp
@@ -446,6 +446,39 @@ namespace Nif
         }
     }
 
+    std::vector<unsigned short> NiSkinPartition::Partition::getTrueTriangles() const
+    {
+        if (!trueTriangles.empty())
+            return trueTriangles;
+
+        std::vector<unsigned short> remappedTriangles;
+        if (vertexMap.empty() || triangles.empty())
+            return remappedTriangles;
+
+        remappedTriangles = triangles;
+
+        for (unsigned short& index : remappedTriangles)
+            index = vertexMap[index];
+        return remappedTriangles;
+    }
+
+    std::vector<std::vector<unsigned short>> NiSkinPartition::Partition::getTrueStrips() const
+    {
+        if (!trueTriangles.empty())
+            return {};
+
+        std::vector<std::vector<unsigned short>> remappedStrips;
+        if (vertexMap.empty() || strips.empty())
+            return remappedStrips;
+
+        remappedStrips = strips;
+        for (auto& strip : remappedStrips)
+            for (auto& index : strip)
+                index = vertexMap[index];
+
+        return remappedStrips;
+    }
+
     void NiMorphData::read(NIFStream* nif)
     {
         int morphCount = nif->getInt();
diff --git a/components/nif/data.hpp b/components/nif/data.hpp
index ef02889d60..6f0ca25237 100644
--- a/components/nif/data.hpp
+++ b/components/nif/data.hpp
@@ -222,7 +222,10 @@ namespace Nif
             std::vector<unsigned short> trueTriangles;
             std::vector<char> boneIndices;
             BSVertexDesc mVertexDesc;
+
             void read(NIFStream* nif);
+            std::vector<unsigned short> getTrueTriangles() const;
+            std::vector<std::vector<unsigned short>> getTrueStrips() const;
         };
         unsigned int mPartitionNum;
         std::vector<Partition> mPartitions;
diff --git a/components/nifbullet/bulletnifloader.cpp b/components/nifbullet/bulletnifloader.cpp
index b3837fc4c9..251795eb21 100644
--- a/components/nifbullet/bulletnifloader.cpp
+++ b/components/nifbullet/bulletnifloader.cpp
@@ -385,6 +385,7 @@ namespace NifBullet
 
         if (!niGeometry.skin.empty())
             args.mAnimated = false;
+        // TODO: handle NiSkinPartition
 
         std::unique_ptr<btTriangleMesh> childMesh = makeChildMesh(niGeometry);
         if (childMesh == nullptr || childMesh->getNumTriangles() == 0)
diff --git a/components/nifosg/nifloader.cpp b/components/nifosg/nifloader.cpp
index 98cc25f90d..3d7d4aedd8 100644
--- a/components/nifosg/nifloader.cpp
+++ b/components/nifosg/nifloader.cpp
@@ -1376,45 +1376,85 @@ namespace NifOsg
             const Nif::NiGeometry* niGeometry = static_cast<const Nif::NiGeometry*>(nifNode);
             if (niGeometry->data.empty())
                 return;
-            const Nif::NiGeometryData* niGeometryData = niGeometry->data.getPtr();
 
-            if (niGeometry->recType == Nif::RC_NiTriShape || nifNode->recType == Nif::RC_BSLODTriShape)
-            {
-                if (niGeometryData->recType != Nif::RC_NiTriShapeData)
-                    return;
-                auto triangles = static_cast<const Nif::NiTriShapeData*>(niGeometryData)->triangles;
-                if (triangles.empty())
-                    return;
-                geometry->addPrimitiveSet(new osg::DrawElementsUShort(
-                    osg::PrimitiveSet::TRIANGLES, triangles.size(), (unsigned short*)triangles.data()));
-            }
-            else if (niGeometry->recType == Nif::RC_NiTriStrips)
+            bool hasPartitions = false;
+            if (!niGeometry->skin.empty())
             {
-                if (niGeometryData->recType != Nif::RC_NiTriStripsData)
-                    return;
-                auto data = static_cast<const Nif::NiTriStripsData*>(niGeometryData);
-                bool hasGeometry = false;
-                for (const auto& strip : data->strips)
+                const Nif::NiSkinInstance* skin = niGeometry->skin.getPtr();
+                const Nif::NiSkinData* data = nullptr;
+                const Nif::NiSkinPartition* partitions = nullptr;
+                if (!skin->data.empty())
                 {
-                    if (strip.size() < 3)
-                        continue;
-                    geometry->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLE_STRIP,
-                        strip.size(), reinterpret_cast<const unsigned short*>(strip.data())));
-                    hasGeometry = true;
+                    data = skin->data.getPtr();
+                    if (!data->partitions.empty())
+                        partitions = data->partitions.getPtr();
+                }
+                if (!partitions && !skin->partitions.empty())
+                    partitions = skin->partitions.getPtr();
+
+                hasPartitions = partitions != nullptr;
+                if (hasPartitions)
+                {
+                    std::vector<unsigned short> trueTriangles;
+                    for (const Nif::NiSkinPartition::Partition& partition : partitions->mPartitions)
+                    {
+                        trueTriangles = partition.getTrueTriangles();
+                        if (!trueTriangles.empty())
+                        {
+                            geometry->addPrimitiveSet(new osg::DrawElementsUShort(
+                                osg::PrimitiveSet::TRIANGLES, trueTriangles.size(), trueTriangles.data()));
+                        }
+                        const std::vector<std::vector<unsigned short>> trueStrips = partition.getTrueStrips();
+                        for (const auto& strip : trueStrips)
+                        {
+                            geometry->addPrimitiveSet(new osg::DrawElementsUShort(
+                                osg::PrimitiveSet::TRIANGLE_STRIP, strip.size(), strip.data()));
+                        }
+                    }
                 }
-                if (!hasGeometry)
-                    return;
             }
-            else if (niGeometry->recType == Nif::RC_NiLines)
+
+            const Nif::NiGeometryData* niGeometryData = niGeometry->data.getPtr();
+            if (!hasPartitions)
             {
-                if (niGeometryData->recType != Nif::RC_NiLinesData)
-                    return;
-                auto data = static_cast<const Nif::NiLinesData*>(niGeometryData);
-                const auto& line = data->lines;
-                if (line.empty())
-                    return;
-                geometry->addPrimitiveSet(new osg::DrawElementsUShort(
-                    osg::PrimitiveSet::LINES, line.size(), reinterpret_cast<const unsigned short*>(line.data())));
+                if (niGeometry->recType == Nif::RC_NiTriShape || nifNode->recType == Nif::RC_BSLODTriShape)
+                {
+                    if (niGeometryData->recType != Nif::RC_NiTriShapeData)
+                        return;
+                    auto triangles = static_cast<const Nif::NiTriShapeData*>(niGeometryData)->triangles;
+                    if (triangles.empty())
+                        return;
+                    geometry->addPrimitiveSet(new osg::DrawElementsUShort(
+                        osg::PrimitiveSet::TRIANGLES, triangles.size(), (unsigned short*)triangles.data()));
+                }
+                else if (niGeometry->recType == Nif::RC_NiTriStrips)
+                {
+                    if (niGeometryData->recType != Nif::RC_NiTriStripsData)
+                        return;
+                    auto data = static_cast<const Nif::NiTriStripsData*>(niGeometryData);
+                    bool hasGeometry = false;
+                    for (const auto& strip : data->strips)
+                    {
+                        if (strip.size() < 3)
+                            continue;
+                        geometry->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLE_STRIP,
+                            strip.size(), reinterpret_cast<const unsigned short*>(strip.data())));
+                        hasGeometry = true;
+                    }
+                    if (!hasGeometry)
+                        return;
+                }
+                else if (niGeometry->recType == Nif::RC_NiLines)
+                {
+                    if (niGeometryData->recType != Nif::RC_NiLinesData)
+                        return;
+                    auto data = static_cast<const Nif::NiLinesData*>(niGeometryData);
+                    const auto& line = data->lines;
+                    if (line.empty())
+                        return;
+                    geometry->addPrimitiveSet(new osg::DrawElementsUShort(
+                        osg::PrimitiveSet::LINES, line.size(), reinterpret_cast<const unsigned short*>(line.data())));
+                }
             }
             handleNiGeometryData(geometry, niGeometryData, boundTextures, nifNode->name);