I am attempting to use the DistributedObject system to create a base for my game and am having a bit of a hard time figuring out how to work the DistributedNode so that I can render the node on all clients. Can anyone please shed some light on this for me please? A small example of how to get a client to render a distributed node would be great.
EDIT: look near the bottom for the most up to date code 
-=Z=-
FWIW: I found 2 videos that I am currently trying to watch and understand. They are a bit over a year old, so maybe some of the more knowledgeable people here can tell us if the info still applies.
video.google.com/videoplay?docid ā¦ 1394&hl=en
video.google.com/videoplay?docid ā¦ 3409&hl=en
Enjoy!
I have watched both of these and were very helpfull for concepts but they donāt go into implementation at all. Any help with implementation of this? I have managed to get the basics of the system working but canāt quite figure out how to work with the DistributedNode class. I have managed to get a working sample using a class that inherits DistributedObject but canāt quite figure out what to do with the DistributedNode and how to get it into the scene graph of the clients.
Do you have anywhere you can post what yo have? I am going to try to figure this out as well, so maybe we can work on it together. I have noticed that networking questions on this forum seem to be a bit scarce for answers, so it may be up to us.
Another problem I found. I was going to try to follow along with the client video, but a search for *.dc in my panda-1.5.4 directory does not reveal the existence of the samples.dc file they discuss. Are the videos still applicable to the current versions of Panda?
They are in the source only, I think.
panda3d.cvs.sourceforge.net/view ā¦ iew=markup
or a more elaborate one:
panda3d.cvs.sourceforge.net/view ā¦ iew=markup
Here is what I have so far. It is a work in progress and currently does work. Feel free to make suggestions. I have setVerbose so it will display lots of debugging info in the console.
import direct.directbase.DirectStart
from direct.showbase.ShowBaseGlobal import *
from direct.showbase.DirectObject import DirectObject
from direct.distributed.DistributedObject import *
from direct.distributed.DistributedSmoothNode import *
from direct.distributed.ClientRepository import *
from direct.distributed.ServerRepository import *
from direct.interval.IntervalGlobal import *
class Avatar(DistributedNode.DistributedNode):
def __init__(self,cr):
self.cr = cr
self.name = "workstation"
self.zone = 1
self.myBody = 0
self.x = 0
self.y = 0
self.z = 0
self.h = 0
self.p = 0
self.r = 0
def setName(self, name):
self.name = name
def getName(self):
return self.name
def tellPlayer(self, message):
print "SELF:",self
print "message from "+self.name+">"+message
class Server(DirectObject.DirectObject):
def __init__(self):
self.serverRepository = ServerRepository(tcpPort=4400,udpPort=4400,dcFileNames=["base2.dc"])
print "Server Repository instantiated"
class Client(DirectObject.DirectObject):
def __init__(self):
self.clientRepository = ClientRepository(dcFileNames=["base2.dc"])
self.clientRepository.setVerbose(1)
self.host = "127.0.0.1"
self.avatar = 0
self.zone = 1
def connectToServer(self, host, port):
if(self.clientRepository.isConnected()): return
self.clientRepository.connect([URLSpec("http://"+host+":"+port)],
self.connectSuccess,[],self.connectFail,[])
def connectSuccess(self):
print "Connected to server"
base.taskMgr.add(self.tskMonitorConnection,"tskMonitorConnection")
def connectFail(self):
print "Connection to host failed"
def tskMonitorConnection(self, task):
if(self.clientRepository.isConnected() == 0):
print "Connection to server lost"
return Task.done
if(self.avatar == 0):
if(self.clientRepository.haveCreateAuthority()):
self.avatar = self.clientRepository.createWithRequired("Avatar",1)
NodePath.__init__(self.avatar, 'avatar')
return Task.cont
def setZone(self, task):
self.clientRepository.sendSetZoneMsg(self.zone)
return Task.done
class World(DirectObject.DirectObject):
def __init__(self):
self.myClient = Client()
self.acceptOnce("c",self.connectToServer)
self.acceptOnce("s",self.startServer)
self.accept("t",self.sendText)
def connectToServer(self):
self.myClient.connectToServer("localhost","4400")
# can't send this too soon or it gets lost so send it in the next frame
base.taskMgr.doMethodLater(0,self.myClient.setZone,"setzone")
def startServer(self):
myServer = Server()
def sendText(self):
print ":",self.myClient
self.myClient.avatar.sendUpdate("tellPlayer",["hello"])
w = World()
run()I figured out the problem with inheritance. I had to modify the dc file because it didnāt like some of the stuff in there for some reason.
Here is an updated version where the ātā key sends a set_xyz update out. Now the question is, how do I get some geometry associated with the thing so the clients on both ends can see each other?
Here is the updated code that I have so far:
base.dc
from direct.distributed import DistributedObject
from direct.distributed import DistributedNode
from newServer import Movable, Avatar
typedef uint32 DoId;
import types;
dclass Movable {
set_xyz(int16 x, int16 y, int16 z) required broadcast ram;
set_hpr(int16 h, int16 p, int16 r) required broadcast ram;
};
dclass Avatar : Movable {
setName(string text) required broadcast;
tellPlayer(string message) broadcast;
};newServer.py (I know this isnāt a very good name for this)
import direct.directbase.DirectStart
from direct.showbase.ShowBaseGlobal import *
from direct.showbase.DirectObject import DirectObject
from direct.distributed.DistributedObject import *
from direct.distributed.DistributedSmoothNode import *
from direct.distributed.ClientRepository import *
from direct.distributed.ServerRepository import *
from direct.interval.IntervalGlobal import *
class Movable(DistributedNode.DistributedNode):
def __init__(self,cr):
DistributedNode.__init__(self,cr)
self.x = 0
self.y = 0
self.z = 0
def set_xyz(self,x,y,z):
self.x = x
self.y = y
self.z = z
def get_xyz(self):
return tuple((self.x,self.y,self.z))
def set_hpr(self,h,p,r):
self.h = h
self.p = p
self.r = r
def get_hpr(self):
return tuple((self.h,self.p,self.h))
class Avatar(Movable):
def __init__(self,cr):
self.cr = cr
self.name = "workstation"
self.zone = 1
self.myBody = 0
self.x = 0
self.y = 0
self.z = 0
self.h = 0
self.p = 0
self.r = 0
def setName(self, name):
self.name = name
def getName(self):
return self.name
def tellPlayer(self, message):
print "SELF:",self
print "message from "+self.name+">"+message
class Server(DirectObject.DirectObject):
def __init__(self):
self.serverRepository = ServerRepository(tcpPort=4400,udpPort=4400,dcFileNames=["base.dc"])
print "Server Repository instantiated"
class Client(DirectObject.DirectObject):
def __init__(self):
self.clientRepository = ClientRepository(dcFileNames=["base.dc"])
self.clientRepository.setVerbose(1)
self.host = "127.0.0.1"
self.avatar = 0
self.zone = 1
def connectToServer(self, host, port):
if(self.clientRepository.isConnected()): return
self.clientRepository.connect([URLSpec("http://"+host+":"+port)],
self.connectSuccess,[],self.connectFail,[])
def connectSuccess(self):
print "Connected to server"
base.taskMgr.add(self.tskMonitorConnection,"tskMonitorConnection")
def connectFail(self):
print "Connection to host failed"
def tskMonitorConnection(self, task):
if(self.clientRepository.isConnected() == 0):
print "Connection to server lost"
return Task.done
if(self.avatar == 0):
if(self.clientRepository.haveCreateAuthority()):
self.avatar = self.clientRepository.createWithRequired("Avatar",1)
NodePath.__init__(self.avatar, 'avatar')
return Task.cont
def setZone(self, task):
self.clientRepository.sendSetZoneMsg(self.zone)
return Task.done
class World(DirectObject.DirectObject):
def __init__(self):
self.myClient = Client()
self.acceptOnce("c",self.connectToServer)
self.acceptOnce("s",self.startServer)
self.accept("t",self.sendText)
def connectToServer(self):
self.myClient.connectToServer("localhost","4400")
# can't send this too soon or it gets lost so send it in the next frame
base.taskMgr.doMethodLater(0,self.myClient.setZone,"setzone")
def startServer(self):
myServer = Server()
def sendText(self):
print ":",self.myClient
self.myClient.avatar.sendUpdate("set_xyz",[2,2,2])
w = World()
run()After fooling with this some more I am getting stumped. Here is what Iām trying to do:
class Movable(DistributedNode.DistributedNode):
def __init__(self,cr):
DistributedNode.__init__(self,cr)
self.x = 0
self.y = 0
self.z = 0
def set_xyz(self,x,y,z):
self.x = x
self.y = y
self.z = z
self.setPos(x,y,z) #trying to set the position here
def get_xyz(self):
return tuple((self.x,self.y,self.z))
Now when the second client is connecting and doing the generate this is the error I get:
Any help with this would be greatly appreciated. The first part of this is the debugging info that is produced in the console.
Connected to server
ConnectionRepository sending datagram:
0000 1d 00 01 00 00 00 ......
CR::SEND:CLIENT_SET_ZONE_CMU
0000 1d 00 01 00 00 00 ......
CR::RECV:CLIENT_SET_DOID_RANGE
0000 4a 00 81 84 1e 00 40 42 0f 00 J.....@B..
CR::RECV:CLIENT_CREATE_OBJECT_REQUIRED_OTHER_OWNER
0000 24 00 01 00 00 00 $.....
ConnectionRepository sending datagram:
0000 22 00 01 00 00 00 01 00 81 84 1e 00 00 00 00 00 "...............
0010 00 00 00 00 00 00 00 00 0b 00 77 6f 72 6b 73 74 ..........workst
0020 61 74 69 6f 6e ation
CR::SEND:CLIENT_CREATE_OBJECT_REQUIRED_RESP
0000 22 00 01 00 00 00 01 00 81 84 1e 00 00 00 00 00 "...............
0010 00 00 00 00 00 00 00 00 0b 00 77 6f 72 6b 73 74 ..........workst
0020 61 74 69 6f 6e ation
CR::RECV:CLIENT_CREATE_OBJECT_REQUIRED_RESP
0000 22 00 01 00 41 42 0f 00 00 00 00 00 00 00 00 00 "...AB..........
0010 00 00 00 00 0b 00 77 6f 72 6b 73 74 61 74 69 6f ......workstatio
0020 6e n
Traceback (most recent call last):
File "C:\Panda3D-1.6.1\direct\distributed\ConnectionRepository.py", line 579,
in readerPollUntilEmpty
while self.readerPollOnce():
File "C:\Panda3D-1.6.1\direct\distributed\ConnectionRepository.py", line 586,
in readerPollOnce
self.handleDatagram(self.private__di)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 140, in h
andleDatagram
self.handleGenerateWithRequired(di)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 170, in h
andleGenerateWithRequired
distObj = self.generateWithRequiredFields(dclass, doId, di)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 210, in g
enerateWithRequiredFields
distObj.updateRequiredFields(dclass, di)
File "C:\Panda3D-1.6.1\direct\distributed\DistributedObject.py", line 334, in
updateRequiredFields
dclass.receiveUpdateBroadcastRequired(self, di)
File "C:\Panda3D-1.6.1\serverClient\newServer.py", line 18, in set_xyz
self.setPos(x,y,z)
AttributeError: C++ object is not yet constructed, or already destructed.
:task(error): Exception occurred in PythonTask readerPollTask
Traceback (most recent call last):
File "newServer.py", line 120, in <module>
w = World()
File "newServer.py", line 102, in __init__
self.myClient = Client()
File "newServer.py", line 63, in __init__
self.clientRepository = ClientRepository(dcFileNames=["base.dc"])
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 16, in __
init__
ClientRepositoryBase.__init__(self, dcFileNames = dcFileNames)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepositoryBase.py", line 46, i
n __init__
self.readDCFile(dcFileNames)
File "C:\Panda3D-1.6.1\direct\distributed\ConnectionRepository.py", line 286,
in readDCFile
self.importModule(dcImports, moduleName, importSymbols)
File "C:\Panda3D-1.6.1\direct\distributed\ConnectionRepository.py", line 383,
in importModule
module = __import__(moduleName, globals(), locals(), importSymbols)
File "C:\Panda3D-1.6.1\serverClient\newServer.py", line 121, in <module>
run()
File "C:\Panda3D-1.6.1\direct\showbase\ShowBase.py", line 2423, in run
self.taskMgr.run()
File "C:\Panda3D-1.6.1\direct\task\TaskNew.py", line 471, in run
self.step()
File "C:\Panda3D-1.6.1\direct\task\TaskNew.py", line 429, in step
self.mgr.poll()
File "C:\Panda3D-1.6.1\direct\distributed\ConnectionRepository.py", line 579,
in readerPollUntilEmpty
while self.readerPollOnce():
File "C:\Panda3D-1.6.1\direct\distributed\ConnectionRepository.py", line 586,
in readerPollOnce
self.handleDatagram(self.private__di)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 140, in h
andleDatagram
self.handleGenerateWithRequired(di)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 170, in h
andleGenerateWithRequired
distObj = self.generateWithRequiredFields(dclass, doId, di)
File "C:\Panda3D-1.6.1\direct\distributed\ClientRepository.py", line 210, in g
enerateWithRequiredFields
distObj.updateRequiredFields(dclass, di)
File "C:\Panda3D-1.6.1\direct\distributed\DistributedObject.py", line 334, in
updateRequiredFields
dclass.receiveUpdateBroadcastRequired(self, di)
File "C:\Panda3D-1.6.1\serverClient\newServer.py", line 18, in set_xyz
self.setPos(x,y,z)
AttributeError: C++ object is not yet constructed, or already destructed.This error is getting thrown before any calls to this method, during the generate process.
Any thoughts?
Hmm, Iām not able to reproduce the problem. Can you post the exact code that generates this error?
David
Actually I have gotten this working. Iām in the process of adding some simple keyboard-based steering and polishing things up some. Once I get it finished Iāll post it here to share.
Here is a full example of using a DistributedNode across multiple clients. You need 2 files to make this work. First you need the base.dc file and distributedNodeDemo.py
Enjoy!
base.dc
from direct.distributed import DistributedObject
from direct.distributed import DistributedNode
from distributedNodeDemo import Movable, Avatar
typedef uint32 DoId;
import types;
dclass Movable {
set_y(int16 y) required broadcast ram;
set_h(int16 h) required broadcast ram;
set_xyz(int16 x, int16 y, int16 z) required broadcast ram;
set_hpr(int16 h, int16 p, int16 r) required broadcast ram;
};
dclass Avatar : Movable {
setName(string text) required broadcast;
tellPlayer(string message) broadcast;
};distributedNodeDemo.py
#######################################################################
## This sample program shows how to use a DistributedNode that shows ##
## up on multiple clients and is updated across the network without ##
## dealing with low level sockets and datagrams hardly at all ##
## ##
## Feel free to make any suggestion/modifications ##
## Enjoy! ##
## ##
## -=Zanz=- May 2009 ##
#######################################################################
import direct.directbase.DirectStart
from direct.showbase.ShowBaseGlobal import *
from direct.showbase.DirectObject import DirectObject
from direct.distributed.DistributedObject import *
from direct.distributed.DistributedSmoothNode import *
from direct.distributed.ClientRepository import *
from direct.distributed.ServerRepository import *
from direct.gui.OnscreenText import OnscreenText
font = loader.loadFont("cmss12")
def addTitle(text):
return OnscreenText(text=text, style=1, fg=(1,1,1,1), font = font,
pos=(1.3,-0.95), align=TextNode.ARight, scale = .07)
def addInstructions(pos, msg):
return OnscreenText(text=msg, style=1, fg=(1,1,1,1), font = font,
pos=(-1.3, pos), align=TextNode.ALeft, scale = .05)
# Our Movable class that can be inherited into subclasses such as the Avatar class
# to allow the subclass to be moved around as a DistributedNode
class Movable(DistributedNode.DistributedNode):
def __init__(self,cr):
DistributedNode.DistributedNode.__init__(self,cr)
# you have to initialize NodePath.__init__() here because it is not called
# in DistributedNode.DistributedNode.__init__()
NodePath.__init__(self, 'avatar')
# all the required methods as defined in the base.dc file
# note: for each method defined in the dc file that begins with
# set needs a corresponding get method in the class definition
def set_y(self,y):
self.setY(self,y)
def get_y(self):
return self.getY()
def set_xyz(self,x,y,z):
self.setPos(x,y,z)
def get_xyz(self):
return tuple((self.getX(),self.getY(),self.getZ()))
def set_h(self,h):
self.setH(self,h)
def get_h(self):
return self.getH()
def set_hpr(self,h,p,r):
self.setHpr(h,p,r)
def get_hpr(self):
return tuple((self.getH(),self.getP(),self.getR()))
class Avatar(Movable):
def __init__(self,cr):
Movable.__init__(self,cr)
self.cr = cr
self.name = "unknown"
self.zone = 1
s = loader.loadModel('smiley')
s.reparentTo(self)
self.reparentTo(render)
# required fields as defined in the base.dc file
def setName(self, name):
self.name = name
def getName(self):
return self.name
def tellPlayer(self, message):
print "message from "+self.name+">"+message
class MyClientRepository(ClientRepository):
def __init__(self,dcFileNames):
ClientRepository.__init__(self, dcFileNames)
# we need to delete the local instance of the distributed Avatar when the server tells us to
def handleDelete(self,di):
doId = di.getUint32()
do = self.doId2do.get(doId)
do.delete()
class Server(DirectObject.DirectObject):
def __init__(self):
self.serverRepository = ServerRepository(tcpPort=4400,udpPort=4400,dcFileNames=["base.dc"])
print "Server Repository instantiated"
class Client(DirectObject.DirectObject):
def __init__(self):
self.clientRepository = MyClientRepository(dcFileNames=["base.dc"])
#self.clientRepository.setVerbose(1)
self.clientRepository.notify.setDebug(0)
self.host = "127.0.0.1"
self.port = "4400"
self.avatar = 0
self.zone = 1
def connectToServer(self, host, port):
if(self.clientRepository.isConnected()): return
self.clientRepository.connect([URLSpec("http://"+host+":"+port)],
self.connectSuccess,[],self.connectFail,[])
def connectSuccess(self):
print "Connected to server"
base.taskMgr.add(self.tskMonitorConnection,"tskMonitorConnection")
def connectFail(self):
print "Connection to host failed"
def tskMonitorConnection(self, task):
if(self.clientRepository.isConnected() == 0):
print "Connection to server lost"
return Task.done
if(self.avatar == 0):
if(self.clientRepository.haveCreateAuthority()):
# this is telling the repository to create a distributed instance
self.avatar = self.clientRepository.createWithRequired("Avatar",1)
base.camera.setPos(0,-0.5,0.4)
base.camera.reparentTo(self.avatar)
base.camera.setH(180)
return Task.cont
def setZone(self, task):
self.clientRepository.sendSetZoneMsg(self.zone)
return Task.done
class World(DirectObject.DirectObject):
def __init__(self):
self.title = addTitle("DistributedNode Demo")
self.inst2 = addInstructions(0.90, "[Left Arrow]: Rotate Left")
self.inst3 = addInstructions(0.85, "[Right Arrow]: Rotate Right")
self.inst4 = addInstructions(0.80, "[Up Arrow]: Move Forward")
self.inst8 = addInstructions(0.75, "[Down Arrow]: Move Backwards")
self.inst7 = addInstructions(0.70, "[o]: toggle oobe")
self.inst9 = addInstructions(0.65, "[s]: Start server")
self.inst10= addInstructions(0.60, "[c]: Connect to server")
self.oobe = 0
self.myClient = Client()
self.acceptOnce("c", self.connectToServer)
self.acceptOnce("s", self.startServer)
self.accept("arrow_up", self.moveForward)
self.accept("arrow_down", self.moveBackward)
self.accept("arrow_left", self.turnLeft)
self.accept("arrow_right", self.turnRight)
self.accept("o",self.setOobe)
base.disableMouse()
def connectToServer(self):
self.myClient.connectToServer(self.myClient.host,self.myClient.port)
# can't send this too soon or it gets lost so send it in the next frame
base.taskMgr.doMethodLater(0,self.myClient.setZone,"setzone")
def startServer(self):
myServer = Server()
# understand that this is not the best method for steering
# but is for demonstration purposes and simplicity only
def moveForward(self):
#send the update to the other clients
self.myClient.avatar.sendUpdate("set_y",[-1])
#update our own instance
self.myClient.avatar.setY(self.myClient.avatar, -1)
def moveBackward(self):
self.myClient.avatar.sendUpdate("set_y",[+1])
self.myClient.avatar.setY(self.myClient.avatar, +1)
def turnLeft(self):
self.myClient.avatar.sendUpdate("set_h",[+12])
self.myClient.avatar.setH(self.myClient.avatar, +12)
def turnRight(self):
self.myClient.avatar.sendUpdate("set_h",[-12])
self.myClient.avatar.setH(self.myClient.avatar, -12)
def setOobe(self):
base.oobe()
w = World()
run()-=Zanz=-
**EDIT: note that the clients all spawn in the same position so youāll have to move one to see the other 
Iāll try to remedy this eventually with an offset or something **
Extremely awesome! I am starting to dig through the code and understand it now, but the examples work wonderfully, and appear very well documented.
For anyone else trying the samples out, a word of advice: Start 2 copies of the game. Press āsā in the first one to make that a server, then ācā to connect it to the server. Donāt try to make any movement on that one.
In the other, press ācā to connect to the server ( the first one). At that point, in one of the clients, move forward a couple times. You will see the white ball in the other client moving away. Keep on the same client, and turn around, and you can look at each other.
Thanks again, Zanz!
Itās also fun to open about 3 or 4 of these windows at once, resize them so they all fit on the screen and move them around to see how the perspective of the different clients change as you move around.
Like this:
Also neat to toggle oobe and look at the scene from birdās eye view. 
I have been playing with this, and it is pretty cool. Do you know what the SetZone method is for? Does it filter the passed info somehow?
Thanks!
setZone is for network visibility. Think in terms of different rooms. Only clients that have the same zone number receive each otherās updates.
David
@Tutunkommon: I would suggest watching those video lectures again on the DistributedObject system to get a good understanding of what zones are and how interest and location work. They explain it pretty in-depth in there.
I am now thinking of the next step. I have been looking through the API at different classes that are distributed and wonder why these classes are left undocumented. Is there noone out there that understands this system enough to write some brief docs on it? At least a brief description of what each of the methods is supposed to do instead of just āUndocumented functionā. I want to combine smoothing with a good steering method so I will most likely be looking at the DistributedSmoothNode and the GravityWalker classes. Iāll try to figure these out and pass along any discoveries here to the forum. Any suggestions by people who know this system or have used these classes would be greatly appreciated. Letās remove the shroud of darkness that covers this system for everyoneās benefit.
Weād love to have some good documentation there. Your work here is greatly appreciated.
If youād like to add some pages to the manual about this, it would be awesome. The manual, of course, can be directly edited. Also, you can add text for the āundocumented functionsā by putting a doc string in the Python code, or a leading comment in C++ code. Weāll happily accept patches to the code as needed.
David
drwr: could you perhaps post a quick example of how to implement the DistributedSmoothNode? I am playing with it but havenāt gotten any smoothing going. Do I need to have a task running to get smooth positions? Iām just not quite sure what to do with this thing yet. Iāll keep experimenting also and try to look at the source for the class. I have changed the base class for my example to a DistributedSmoothNode and called avatar.activeSmoothing(1,0). It complained about not having an attribute named smoother so I assumed it wanted a SmoothMover class here so I added avatar.smoother = SmoothMover()
What other magical settings do i need to start seeing some results? Thanks for your help with this. Once I figure out how the system works Iād be happy to try to document some of it for others and hope that this thread will also be of help to others like myself.
-=Z=-
self.smoother should have been created in generate(), which should have been called when the DistributedObject became visible. Perhaps you have to call generate() explicitly on your local object when you create it.
David