From ec9a1b0d0526c9aba7d7cdd0e68789ab0e747d50 Mon Sep 17 00:00:00 2001
From: Andrei Kortunov <andrei.kortunov@yandex.ru>
Date: Mon, 30 Jul 2018 08:24:30 +0400
Subject: [PATCH] Handle RootCollisionNode, attached to non-root node (bug
 #4311)

---
 CHANGELOG.md                             |  1 +
 components/nifbullet/bulletnifloader.cpp | 42 ++++++++++++++++--------
 components/nifbullet/bulletnifloader.hpp |  4 +--
 3 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5b62bf1a..1d6a20cac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,6 +36,7 @@
     Bug #4291: Non-persistent actors that started the game as dead do not play death animations
     Bug #4293: Faction members are not aware of faction ownerships in barter
     Bug #4307: World cleanup should remove dead bodies only if death animation is finished
+    Bug #4311: OpenMW does not handle RootCollisionNode correctly
     Bug #4327: Missing animations during spell/weapon stance switching
     Bug #4358: Running animation is interrupted when magic mode is toggled
     Bug #4368: Settings window ok button doesn't have key focus by default
diff --git a/components/nifbullet/bulletnifloader.cpp b/components/nifbullet/bulletnifloader.cpp
index be5a7d9d6..6f8c8f2c0 100644
--- a/components/nifbullet/bulletnifloader.cpp
+++ b/components/nifbullet/bulletnifloader.cpp
@@ -94,13 +94,16 @@ osg::ref_ptr<Resource::BulletShape> BulletNifLoader::load(const Nif::NIFFilePtr&
     }
     else
     {
-        bool autogenerated = hasAutoGeneratedCollision(node);
-
         // files with the name convention xmodel.nif usually have keyframes stored in a separate file xmodel.kf (see Animation::addAnimSource).
         // assume all nodes in the file will be animated
         const bool isAnimated = pathFileNameStartsWithX(nif->getFilename());
 
-        handleNode(node, 0, autogenerated, isAnimated, autogenerated);
+        // If the mesh has RootCollisionNode, attached to actual root node, use it as collision mesh
+        const Nif::Node* rootCollisionNode = getCollisionNode(node);
+        if (rootCollisionNode)
+            handleNode(nif->getFilename(), rootCollisionNode, 0, false, isAnimated, false);
+        else
+            handleNode(nif->getFilename(), node, 0, true, isAnimated, true);
 
         if (mCompoundShape)
         {
@@ -153,25 +156,34 @@ bool BulletNifLoader::findBoundingBox(const Nif::Node* node, int flags)
     return false;
 }
 
-bool BulletNifLoader::hasAutoGeneratedCollision(const Nif::Node* rootNode)
+const Nif::Node* BulletNifLoader::getCollisionNode(const Nif::Node* rootNode)
 {
     const Nif::NiNode *ninode = dynamic_cast<const Nif::NiNode*>(rootNode);
     if(ninode)
     {
+        // If root NiNode has only other NiNode as child, consider it as a wrapper, not as actual root node
         const Nif::NodeList &list = ninode->children;
-        for(size_t i = 0;i < list.length();i++)
+        if (list.length() == 1 &&
+            rootNode->recType == Nif::RC_NiNode &&
+            list[0].getPtr()->recType == Nif::RC_NiNode)
         {
-            if(!list[i].empty())
-            {
-                if(list[i].getPtr()->recType == Nif::RC_RootCollisionNode)
-                    return false;
-            }
+            return getCollisionNode(list[0].getPtr());
+        }
+
+        for(size_t i = 0; i < list.length(); i++)
+        {
+            if(list[i].empty())
+                continue;
+
+            const Nif::Node* childNode = list[i].getPtr();
+            if(childNode->recType == Nif::RC_RootCollisionNode)
+                return childNode;
         }
     }
-    return true;
+    return nullptr;
 }
 
-void BulletNifLoader::handleNode(const Nif::Node *node, int flags,
+void BulletNifLoader::handleNode(const std::string& fileName, const Nif::Node *node, int flags,
                                          bool isCollisionNode, bool isAnimated, bool autogenerated)
 {
     // Accumulate the flags from all the child nodes. This works for all
@@ -184,6 +196,9 @@ void BulletNifLoader::handleNode(const Nif::Node *node, int flags,
 
     isCollisionNode = isCollisionNode || (node->recType == Nif::RC_RootCollisionNode);
 
+    if (node->recType == Nif::RC_RootCollisionNode && autogenerated)
+        std::cerr << "Found RootCollisionNode attached to non-root node in " << fileName << ". Treat it as a common NiTriShape." << std::endl;
+
     // Don't collide with AvoidNode shapes
     if(node->recType == Nif::RC_AvoidNode)
         flags |= 0x800;
@@ -212,7 +227,6 @@ void BulletNifLoader::handleNode(const Nif::Node *node, int flags,
                 // Marker can still have collision if the model explicitely specifies it via a RootCollisionNode.
                 return;
             }
-
         }
     }
 
@@ -235,7 +249,7 @@ void BulletNifLoader::handleNode(const Nif::Node *node, int flags,
         for(size_t i = 0;i < list.length();i++)
         {
             if(!list[i].empty())
-                handleNode(list[i].getPtr(), flags, isCollisionNode, isAnimated, autogenerated);
+                handleNode(fileName, list[i].getPtr(), flags, isCollisionNode, isAnimated, autogenerated);
         }
     }
 }
diff --git a/components/nifbullet/bulletnifloader.hpp b/components/nifbullet/bulletnifloader.hpp
index fff51933f..8fd9cc2a1 100644
--- a/components/nifbullet/bulletnifloader.hpp
+++ b/components/nifbullet/bulletnifloader.hpp
@@ -55,9 +55,9 @@ public:
 private:
     bool findBoundingBox(const Nif::Node* node, int flags = 0);
 
-    void handleNode(Nif::Node const *node, int flags, bool isCollisionNode, bool isAnimated=false, bool autogenerated=false);
+    void handleNode(const std::string& fileName, Nif::Node const *node, int flags, bool isCollisionNode, bool isAnimated=false, bool autogenerated=false);
 
-    bool hasAutoGeneratedCollision(const Nif::Node *rootNode);
+    const Nif::Node* getCollisionNode(const Nif::Node* rootNode);
 
     void handleNiTriShape(const Nif::NiTriShape *shape, int flags, const osg::Matrixf& transform, bool isAnimated);