Issues with the C4D to Unity Import python plugin - missing some types of objects

jenandesign

Hello, I am trying to figure out why the supplied C4D to Unity importer misses certain types of objects. The plugin itself is essentially just an FBX converter that Unity runs when a c4d file is within one of its Asset directories. It is written in Python and it is very easy for the end user to modify. I fixed SDS object import by adding a few lines of code, seen towards the end, but still cannot seem to get Polygon Reduction objects. Hoping that someone knows something about this, maybe they can shed some light.

I found the definitions in the C++ documentation, which has been helpful, but I don't see anything that looks indicative of Polygon Reductions
https://developers.maxon.net/docs/cpp/2023_2/_ffbxexport_8h.html

"""
Unity C4D To FBX Converter
Written for Cinema 4D R18.020

"""
import platform
import c4d
import sys
import os
from c4d import documents, plugins, threading, utils, gui

# Be sure to use a unique ID obtained from www.plugincafe.com
PLUGIN_ID = 1038605
FBX_EXPORTER_ID = 1026370

FBXEXPORT_TEXTURES = True
FBXEXPORT_EMBED_TEXTURES = False
FBXEXPORT_SAVE_NORMALS = True
FBXEXPORT_ASCII = False

def win32_utf8_argv():                                                                                               
    """
    Adapted from http://code.activestate.com/recipes/572200-get-sysargv-with-unicode-characters-under-windows/

    Uses shell32.GetCommandLineArgvW to get sys.argv as a list of UTF-8
    strings.

    Versions 2.5 and older of Python don't support Unicode in sys.argv on
    Windows, with the underlying Windows API instead replacing multi-byte
    characters with '?'.
    """

    from ctypes import POINTER, byref, cdll, c_int, windll
    from ctypes.wintypes import LPCWSTR, LPWSTR

    GetCommandLineW = cdll.kernel32.GetCommandLineW
    GetCommandLineW.argtypes = []
    GetCommandLineW.restype = LPCWSTR

    CommandLineToArgvW = windll.shell32.CommandLineToArgvW
    CommandLineToArgvW.argtypes = [LPCWSTR, POINTER(c_int)]
    CommandLineToArgvW.restype = POINTER(LPWSTR)

    cmd = GetCommandLineW()
    argc = c_int(0)
    argv = CommandLineToArgvW(cmd, byref(argc))
    if argc.value > 0:
        # Remove Python executable if present
        if argc.value - len(sys.argv) == 1:
            start = 1
        else:
            start = 0
        return [argv[i].encode('utf-8') for i in
                xrange(start, argc.value)]
    else:
        return []

class ExportThread(threading.C4DThread):

    def __init__(self, doc, exportPath):
        self.doc = doc
        self.status = False
        self.exportPath = exportPath

    def Main(self):
        # Export document to FBX
        self.status = documents.SaveDocument(self.doc, self.exportPath, c4d.SAVEDOCUMENTFLAGS_DONTADDTORECENTLIST, FBX_EXPORTER_ID)

    def GetStatus(self):
        return self.status

class MessageLogger():

    def __init__(self, logOutputPath=None):
        self.logString = ""
        if logOutputPath :
            self.logOutputFile = open(logOutputPath, 'w')
        else :
            self.logOutputFile = sys.stdout

    def appendMessage(self,message) :
        self.logString+= message + "\n"

    def writeLog(self, success) :
        if success :
            self.logOutputFile.write("SUCCESS\nframerate=" + str(documents.GetActiveDocument().GetFps()) + "\n")
        else :
            self.logOutputFile.write("FAILURE\n" + self.logString)

        if self.logOutputFile is not sys.stdout :
            self.logOutputFile.close()
        return success

# get command line arguments
def PluginMessage(id, data) :
    if id==c4d.C4DPL_COMMANDLINEARGS:
        if platform.system() == 'Windows':
            argv = win32_utf8_argv()
        else:
            argv = sys.argv

        if '-UnityC4DtoFBX' in argv :
            sourcePath = ""
            destinationPath = ""
            logOutputPath = ""
            textureSearchPath = ""
            # parse command line arguments
            for idx, arg in enumerate(argv):
                if (arg == "-src" and len(argv) > idx) :
                    sourcePath = argv[idx+1]
                if (arg == "-dst" and len(argv) > idx) :
                    destinationPath = argv[idx+1]
                if (arg == "-out" and len(argv) > idx) :
                    logOutputPath = argv[idx+1]
                if (arg == "-textureSearchPath" and len(argv) > idx) :
                    textureSearchPath = argv[idx+1]

            logger = MessageLogger(logOutputPath)
            
            if not sourcePath or not destinationPath :
                logger.appendMessage("Invalid command line arguments")
                return logger.writeLog(False)
            
            # C4D automatically opens any file which path is passed as an argument, 
            # to prevent that, the parameters omit file extensions.
            sourcePath+=".c4d"
            destinationPath+=".fbx"

            # load the c4d scene
            loadedDoc = documents.LoadFile(sourcePath)
            documents.GetActiveDocument().SetDocumentPath(textureSearchPath)
            if loadedDoc :    
                logger.appendMessage("Succesfuly loaded " + sourcePath)
            else :
                logger.appendMessage("Couldn't load " + sourcePath)
                return logger.writeLog(False)
            # execute the conversion
            if ExecuteConversion(destinationPath, textureSearchPath, logger):
                logger.appendMessage("FBX Exported at " + destinationPath)
                return logger.writeLog(True)
            else :
                logger.appendMessage("FBX Plugin failed to export\n")
                return logger.writeLog(False)
        else :
            # command line argument not found. Do nothing.
            return False

def ExecuteConversion(destinationPath, textureSearchPath, logger) :
    plug = plugins.FindPlugin(FBX_EXPORTER_ID, c4d.PLUGINTYPE_SCENESAVER)
    if plug is None:
        logger.appendMessage("FBX Export plugin not found")
        return False

    op = {}
    # Retrieve FBX Eporter settings object
    if plug.Message(c4d.MSG_RETRIEVEPRIVATEDATA, op) :
        if "imexporter" not in op:
            return False

        # BaseList2D object stored in "imexporter" key hold the settings
        fbxExport = op["imexporter"]
        if fbxExport is None :
            return False

        # Change export settings
        
        #THE FOLLOWING TWO LINES OF CODE WERE ADDED TO FIX SDS OBJECT IMPORT
        fbxExport[c4d.FBXEXPORT_SDS_SUBDIVISION] = True
        fbxExport[c4d.FBXEXPORT_SDS] = False
        fbxExport[c4d.FBXEXPORT_TEXTURES] = FBXEXPORT_TEXTURES
        fbxExport[c4d.FBXEXPORT_EMBED_TEXTURES] = FBXEXPORT_EMBED_TEXTURES
        fbxExport[c4d.FBXEXPORT_SAVE_NORMALS] = FBXEXPORT_SAVE_NORMALS
        fbxExport[c4d.FBXEXPORT_ASCII] = FBXEXPORT_ASCII

        c4d.SetGlobalTexturePath(9, documents.GetActiveDocument().GetDocumentPath())
        if textureSearchPath :
            c4d.SetGlobalTexturePath(8, textureSearchPath)

        thread = ExportThread(documents.GetActiveDocument(), destinationPath)
        thread.Start()       # Start thread
        thread.End()         # Then end it but wait until it finishes

        # Retrieve export status and return it
        status = thread.GetStatus()
        return status
    else :
        logger.appendMessage("Could not configure FBX plugin")
        return False

    documents.KillDocument(documents.GetActiveDocument())

m_adam

Hi @jenandesign,

May I ask you which version of Cinema 4D are you using?
So typically the issue with Polygon Reduction is the same as the one from Python plugin(Python Generator?). Are they the only affected objects types or all generators are affected?

In any case, FBX format has no knowledge of what is Polygon Reduction/Python Generator so he has to bake it as polygon Object.
But for doing that it needs a proper cache representation of these generators. And since you Load the file in memory the scene is not yet evaluated (and cache not built).

So please call BaseDocument.ExecutePasses to build the cache.

For more information see related topic Cloner objects missing in Commandline FBX export.

Cheers,
Maxime.

jenandesign

Hi Maxime! Thanks for the info about Poly Reduction and ideas with ExecutePasses I will try that immediately

I am currently on the latest, R21.115. However I tested this same stuff happening on R20 as well.

Cloners are usually okay as long as they don't reference a spline (which now makes sense knowing about the cache thing).

However, I am right now getting a very strange thing where a cloner and a null with dynamics tag (applied to many children) go from importing normally to not.. depending on how many children are in the Fracture.1 null. But perhaps this is a separate issue. When testing with the manual FBX export, it takes some time.. I am assuming it has to animate the dynamics tag to it's current position before exporting... Perhaps unity does not know how to wait for this operation unless it is very fast. Perplexing why it would have anything to do with the cloner, though, as it is not in any way connected to the Fracture.1 null or the dynamics system. Removing one or the other object results in a successful import into unity. The attached scene fails import into unity unless you delete the cloner, the dynamics tag attached to the null, or at least 10-50 more children of the null.fbxtest_v03.c4d. This is different than the original issue I posted about, where the scene import does not fail, but merely comes in with missing objects.

I will try the ExecutePasses thing now! Thanks again!

Leah

jenandesign

ExecutePasses worked for Polygon Reduction objects! That is a huge benefit to LOD versioning in Unity

Added here:

#
#SNIPPET FROM MAIN CODE
#

class ExportThread(threading.C4DThread):

    def __init__(self, doc, exportPath):
        self.doc = doc
        self.status = False
        self.exportPath = exportPath
        #ADDED THE LINE BELOW
        doc.ExecutePasses(None, True, True, True, c4d.BUILDFLAGS_EXPORT)

    def Main(self):
        # Export document to FBX
        self.status = documents.SaveDocument(self.doc, self.exportPath, c4d.SAVEDOCUMENTFLAGS_DONTADDTORECENTLIST, FBX_EXPORTER_ID)

    def GetStatus(self):
        return self.status

#
#SNIPPET FROM MAIN CODE
#

Cloners are still not working if they reference a spline. Any ideas why that is still giving us trouble?

Leah

m_adam

Sometime its needed to call it multiple time. So try to call ExcecutePass multiple time (maximum 3 is enough).

Cheers,
Maxime

jenandesign

@m_adam Shoot, tried calling it 3X and still nothing on the cloner (spline mode) object.

(failing) test file attached
fbxtest_v04.c4d

jenandesign

Currently the Spline Deformer breaks other objects in the scene, while the Bevel Deformer and Cloner Object in Spline Object mode only break themselves.

GetContour? SetOptimizeCache? Anything else worth investigating? Maybe this is happening because it's being called via Unity automatically?

m_adam

If I understand correctly, the issue is that the spline are not saved in the fbx?

If yes make sure to set fbxExport[c4d.FBXEXPORT_SPLINES] = True

At least here is working correctly, loading the saved fbx give me back the same result than previously.
Cheers,
Maxime.

jenandesign

@m_adam Then maybe the issue is that the command line fbx export is being executed from within Unity and not through C4D itself?

Is there some kind of document referencing error that could happen if another program (other than C4D) were to call this script? Would caches behave differently?

To answer your question, yes, I have FBXEXPORT_SPLINES set to True

jenandesign

I forgot to mention, Instances also fail to cache into Unity as well.

I am thinking these are all related and to do with the cache being unavailable unless the script is being run within the C4D gui

m_adam

Hi @jenandesign sorry for the delay and to not have spotted the issue earlier.

But SaveDocument needs to be called in the main thread. So one solution for you is to send a CoreMessage with c4d.SendCoreMessage to catch it in a MessageData and process it.

import c4d

FBX_EXPORTER_ID = 1026370

FBXEXPORT_TEXTURES = True
FBXEXPORT_EMBED_TEXTURES = False
FBXEXPORT_SAVE_NORMALS = True
FBXEXPORT_ASCII = False



# Main function
def main():
    sourcePath = r"C:\Users\graphos\Downloads\fbxtest_v04.c4d"
    destinationPath = r"C:\Users\graphos\Documents\test.fbx"
    
    plug = c4d.plugins.FindPlugin(FBX_EXPORTER_ID, c4d.PLUGINTYPE_SCENESAVER)
    if plug is None:
        logger.appendMessage("FBX Export plugin not found")
        return False

    op = {}
    # Retrieve FBX Eporter settings object
    if plug.Message(c4d.MSG_RETRIEVEPRIVATEDATA, op) :
        if "imexporter" not in op:
            return False

        # BaseList2D object stored in "imexporter" key hold the settings
        fbxExport = op["imexporter"]
        if fbxExport is None :
            return False

        # Change export settings
        
        #THE FOLLOWING TWO LINES OF CODE WERE ADDED TO FIX SDS OBJECT IMPORT
        fbxExport[c4d.FBXEXPORT_SDS_SUBDIVISION] = True
        fbxExport[c4d.FBXEXPORT_SDS] = False
        fbxExport[c4d.FBXEXPORT_TEXTURES] = FBXEXPORT_TEXTURES
        fbxExport[c4d.FBXEXPORT_EMBED_TEXTURES] = FBXEXPORT_EMBED_TEXTURES
        fbxExport[c4d.FBXEXPORT_SAVE_NORMALS] = FBXEXPORT_SAVE_NORMALS
        fbxExport[c4d.FBXEXPORT_ASCII] = FBXEXPORT_ASCII

        doc = c4d.documents.LoadDocument(sourcePath, c4d.SCENEFILTER_OBJECTS | c4d.SCENEFILTER_MATERIALS, None)
        status = False
        doc.ExecutePasses(None, True, True, True, c4d.BUILDFLAGS_EXPORT)

        # Export document to FBX
        status = c4d.documents.SaveDocument(doc, destinationPath, c4d.SAVEDOCUMENTFLAGS_DONTADDTORECENTLIST, FBX_EXPORTER_ID)
        c4d.documents.KillDocument(doc)

        # Retrieve export status and return it
        print status



# Execute main()
if __name__=='__main__':
    main()

Cheers,
Maxime.

jenandesign

Hi Maxime! Thanks for the suggestion, though I don't quite understand what you mean by your example... I don't see any use of SendCoreMessage in your snippet?

SaveDocument is already present in the original code in the extended threading class "ExportThread" under definition Main(). How are you suggesting I change this?

Thank you for the continued help

m_adam

SaveDocument is already present in the original code in the extended threading class "ExportThread"

TO not make it happens in a thread.
So to directly execute it in ExecuteConversion.

The use of SendCoreMessage is a way, from a thread (and it's the case for you in ExportThread::Main) to send a message, that Cinema 4D will process on the Main thread (I didn't use in my code because in my case I'm in the main thread).
So you can react to this message and do something (in your case SaveDocument). It was just for your information, regarding what's your thread is doing (only calling SaveDocument) I would say that using a thread here make no sense, and you should directly call SaveDocument in your ExecuteConversion function.

Hope it's more clear.
Cheers,
Maxime.