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 
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 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
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 Shoot, tried calling it 3X and still nothing on the cloner (spline mode) object.
(failing) test file attached
fbxtest_v04.c4d
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
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
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/Cinema4DCPPSDK/html/_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())
R20
Hello I was wondering why this addition... when you drag an attribute/parameter from the attributes panel into the scripting window to copy the proper baseselect value for a given object, the object type is now added to the beginning....
I thought it was better the way before- when you could drag the parameter and it would only add the baseselect's label "[xxxxxxx]" which meant there was no need to go back and delete the object name because it wasn't copied.
For example now in R20 I make a Python Generator, add a user data link to it, and type on the first line of the main code:
obj = op
After this, I drag the userdata field into the script window after "op", now I have:
obj = opPythonGenerator[c4d.ID_USERDATA,1]
What a mess. It used to be clean.. I would type obj=op, drag in the user data field and it would have added [c4d.ID_USERDATA,1] with no need to delete "PythonGenerator". With R19 and earlier I would have had "obj=op[c4d.ID_USERDATA,1]" with no need to remove the superfluous object type text.
Just wondering if there was a reason to add this, it has been irking me for the last few months of heavy scripting use in C4D and it would be awesome if that was rolled back to the way it was- unless of course there is a reason why it's important to keep that I am missing.
@m_adam Hello thank you for the quick fix, but do you have any further explanation about what the flags and modes specify? The documentation still has no information.
Thank you in advance for "expanding" on this topic. 