Assimp FBX Import support

Issues fixed:
- Updated assimp to latest and backported fixes into godot.
- Fixed file scale being ignored from FBX file.
- Fixed bone removal
- Implemented proper armature binding
- Fixed recursion not always going through the entire path
- Implemented assimp global scaling system
- Fixed assimp global scale process to support unit conversion
- Implemented proper fbx scaling
- Fixed asserts caused by missing faces in some models which could crash
- Fixed valid bone removal
- Fixed root node being overwriten by assimp which caused data loss
- Fixed armature construction so that it works with multiple roots
- Implemented basic support for FBX standard materials
- Refactoring to improve code quality and improve function reuse.
- Simplified node creation from assimp scene into subsections: create_light, create_mesh, create_bone.
- Creating meshes is now done after hierarchy is created so that the skeleton is always available.
- Added support to assimp to support file scale in all formats which call SetFileScale.
- Many other fixes provided into assimp.

Known issues:
- FBX pivots from Maya do not currently work. (workaround: for now use blender import and export to remove pivot tracks)
- Hierarchy creates an extra node for each mesh - this was done intentionally but we intended to do a pass to remove these as they're a required node.
- When an animated mesh has not executed any animation the rest pose is wrong.

Co-authored-by: K. S. Ernest (iFire) Lee <ernest.lee@chibifire.com>

5 files changed, 68 insertions, 156 deletions

diff --git a/thirdparty/assimp/include/assimp/.editorconfig b/thirdparty/assimp/include/assimp/.editorconfig
deleted file mode 100644
index 9ea66423ad..0000000000
--- a/thirdparty/assimp/include/assimp/.editorconfig
+++ /dev/null
@@ -1,8 +0,0 @@
-# See <http://EditorConfig.org> for details
-
-[*.{h,hpp,inl}]
-end_of_line = lf
-insert_final_newline = true
-trim_trailing_whitespace = true
-indent_size = 4
-indent_style = space
diff --git a/thirdparty/assimp/include/assimp/BaseImporter.h b/thirdparty/assimp/include/assimp/BaseImporter.h
index 48dfc8ed8b..55f7fe3754 100644
--- a/thirdparty/assimp/include/assimp/BaseImporter.h
+++ b/thirdparty/assimp/include/assimp/BaseImporter.h
@@ -48,8 +48,10 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <vector>
 #include <set>
+#include <map>
 #include <assimp/types.h>
 #include <assimp/ProgressHandler.hpp>
+#include <assimp/ai_assert.h>
 
 struct aiScene;
 struct aiImporterDesc;
@@ -80,6 +82,10 @@ class IOStream;
 class ASSIMP_API BaseImporter {
     friend class Importer;
 
+private:
+    /* Pushes state into importer for the importer scale */
+    virtual void UpdateImporterScale( Importer* pImp );
+
 public:
 
     /** Constructor to be privately used by #Importer */
@@ -132,7 +138,7 @@ public:
      *  a suitable response to the caller.
      */
     aiScene* ReadFile(
-        const Importer* pImp,
+        Importer* pImp,
         const std::string& pFile,
         IOSystem* pIOHandler
         );
@@ -161,14 +167,65 @@ public:
      *  some loader features. Importers must provide this information. */
     virtual const aiImporterDesc* GetInfo() const = 0;
 
+    /**
+     * Will be called only by scale process when scaling is requested.
+     */
+    virtual void SetFileScale(double scale)
+    {
+        fileScale = scale;
+    }
+
+    virtual double GetFileScale() const
+    {
+        return fileScale;
+    }
+
+    enum ImporterUnits {
+        M,
+        MM,
+        CM,
+        INCHES,
+        FEET
+    };
+
+    /**
+     * Assimp Importer
+     * unit conversions available 
+     * if you need another measurment unit add it below.
+     * it's currently defined in assimp that we prefer meters.
+     * */
+    std::map<ImporterUnits, double> importerUnits = {
+        {ImporterUnits::M, 1},
+        {ImporterUnits::CM, 0.01},
+        {ImporterUnits::MM, 0.001},
+        {ImporterUnits::INCHES, 0.0254},
+        {ImporterUnits::FEET, 0.3048}
+    };
+
+    virtual void SetApplicationUnits( const ImporterUnits& unit )
+    {
+        importerScale = importerUnits[unit];
+        applicationUnits = unit;
+    }
+
+    virtual const ImporterUnits& GetApplicationUnits()
+    {
+        return applicationUnits;
+    }
+
     // -------------------------------------------------------------------
     /** Called by #Importer::GetExtensionList for each loaded importer.
      *  Take the extension list contained in the structure returned by
      *  #GetInfo and insert all file extensions into the given set.
      *  @param extension set to collect file extensions in*/
     void GetExtensionList(std::set<std::string>& extensions);
+    
+protected:    
+    ImporterUnits applicationUnits = ImporterUnits::M;
+    double importerScale = 1.0;
+    double fileScale = 1.0;
+
 
-protected:
 
     // -------------------------------------------------------------------
     /** Imports the given file into the given scene structure. The
diff --git a/thirdparty/assimp/include/assimp/config.h.in b/thirdparty/assimp/include/assimp/config.h.in
index d08b929a10..3a6379bf40 100644
--- a/thirdparty/assimp/include/assimp/config.h.in
+++ b/thirdparty/assimp/include/assimp/config.h.in
@@ -142,7 +142,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 /** @brief  Specifies the maximum angle that may be between two vertex tangents
  *         that their tangents and bi-tangents are smoothed.
  *
- * This applies to the CalcTangentSpace-Step. TFvhe angle is specified
+ * This applies to the CalcTangentSpace-Step. The angle is specified
  * in degrees. The maximum value is 175.
  * Property type: float. Default value: 45 degrees
  */
@@ -999,6 +999,13 @@ enum aiComponent
 #   define AI_CONFIG_GLOBAL_SCALE_FACTOR_DEFAULT  1.0f
 #endif // !! AI_DEBONE_THRESHOLD
 
+#define AI_CONFIG_APP_SCALE_KEY "APP_SCALE_FACTOR"
+
+#if (!defined AI_CONFIG_APP_SCALE_KEY)
+#   define AI_CONFIG_APP_SCALE_KEY 1.0
+#endif // AI_CONFIG_APP_SCALE_KEY
+
+
 // ---------- All the Build/Compile-time defines ------------
 
 /** @brief Specifies if double precision is supported inside assimp
diff --git a/thirdparty/assimp/include/assimp/irrXMLWrapper.h b/thirdparty/assimp/include/assimp/irrXMLWrapper.h
deleted file mode 100644
index ec8ee7c76e..0000000000
--- a/thirdparty/assimp/include/assimp/irrXMLWrapper.h
+++ /dev/null
@@ -1,144 +0,0 @@
-/*
-Open Asset Import Library (assimp)
-----------------------------------------------------------------------
-
-Copyright (c) 2006-2019, assimp team
-
-
-All rights reserved.
-
-Redistribution and use of this software in source and binary forms,
-with or without modification, are permitted provided that the
-following conditions are met:
-
-* Redistributions of source code must retain the above
-copyright notice, this list of conditions and the
-following disclaimer.
-
-* Redistributions in binary form must reproduce the above
-copyright notice, this list of conditions and the
-following disclaimer in the documentation and/or other
-materials provided with the distribution.
-
-* Neither the name of the assimp team, nor the names of its
-contributors may be used to endorse or promote products
-derived from this software without specific prior
-written permission of the assimp team.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-----------------------------------------------------------------------
-*/
-
-#ifndef INCLUDED_AI_IRRXML_WRAPPER
-#define INCLUDED_AI_IRRXML_WRAPPER
-
-// some long includes ....
-#include <irrXML.h>
-#include "IOStream.hpp"
-#include "BaseImporter.h"
-#include <vector>
-
-namespace Assimp    {
-
-// ---------------------------------------------------------------------------------
-/** @brief Utility class to make IrrXML work together with our custom IO system
- *  See the IrrXML docs for more details.
- *
- *  Construct IrrXML-Reader in BaseImporter::InternReadFile():
- *  @code
- * // open the file
- * std::unique_ptr<IOStream> file( pIOHandler->Open( pFile));
- * if( file.get() == NULL) {
- *    throw DeadlyImportError( "Failed to open file " + pFile + ".");
- * }
- *
- * // generate a XML reader for it
- * std::unique_ptr<CIrrXML_IOStreamReader> mIOWrapper( new CIrrXML_IOStreamReader( file.get()));
- * mReader = irr::io::createIrrXMLReader( mIOWrapper.get());
- * if( !mReader) {
- *    ThrowException( "xxxx: Unable to open file.");
- * }
- * @endcode
- **/
-class CIrrXML_IOStreamReader : public irr::io::IFileReadCallBack {
-public:
-
-    // ----------------------------------------------------------------------------------
-    //! Construction from an existing IOStream
-    explicit CIrrXML_IOStreamReader(IOStream* _stream)
-        : stream (_stream)
-        , t (0)
-    {
-
-        // Map the buffer into memory and convert it to UTF8. IrrXML provides its
-        // own conversion, which is merely a cast from uintNN_t to uint8_t. Thus,
-        // it is not suitable for our purposes and we have to do it BEFORE IrrXML
-        // gets the buffer. Sadly, this forces us to map the whole file into
-        // memory.
-
-        data.resize(stream->FileSize());
-        stream->Read(&data[0],data.size(),1);
-
-        // Remove null characters from the input sequence otherwise the parsing will utterly fail
-        unsigned int size = 0;
-        unsigned int size_max = static_cast<unsigned int>(data.size());
-        for(unsigned int i = 0; i < size_max; i++) {
-            if(data[i] != '\0') {
-                data[size++] = data[i];
-            }
-        }
-        data.resize(size);
-
-        BaseImporter::ConvertToUTF8(data);
-    }
-
-    // ----------------------------------------------------------------------------------
-    //! Virtual destructor
-    virtual ~CIrrXML_IOStreamReader() {}
-
-    // ----------------------------------------------------------------------------------
-    //!   Reads an amount of bytes from the file.
-    /**  @param buffer:       Pointer to output buffer.
-     *   @param sizeToRead:   Amount of bytes to read
-     *   @return              Returns how much bytes were read.  */
-    virtual int read(void* buffer, int sizeToRead)  {
-        if(sizeToRead<0) {
-            return 0;
-        }
-        if(t+sizeToRead>data.size()) {
-            sizeToRead = static_cast<int>(data.size()-t);
-        }
-
-        memcpy(buffer,&data.front()+t,sizeToRead);
-
-        t += sizeToRead;
-        return sizeToRead;
-    }
-
-    // ----------------------------------------------------------------------------------
-    //! Returns size of file in bytes
-    virtual int getSize()   {
-        return (int)data.size();
-    }
-
-private:
-    IOStream* stream;
-    std::vector<char> data;
-    size_t t;
-
-}; // ! class CIrrXML_IOStreamReader
-
-} // ! Assimp
-
-#endif // !! INCLUDED_AI_IRRXML_WRAPPER
diff --git a/thirdparty/assimp/include/assimp/scene.h b/thirdparty/assimp/include/assimp/scene.h
index df5d6f3b5e..2667db85b3 100644
--- a/thirdparty/assimp/include/assimp/scene.h
+++ b/thirdparty/assimp/include/assimp/scene.h
@@ -56,9 +56,9 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "material.h"
 #include "anim.h"
 #include "metadata.h"
-#include <cstdlib>
 
 #ifdef __cplusplus
+#  include <cstdlib>
 extern "C" {
 #endif