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<DIV><FONT size=2 face=Arial>Hi <SPAN style="FONT-WEIGHT: bold"><FONT size=3
face="Times New Roman">Nicholas,</FONT></SPAN></FONT></DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN
style="FONT-WEIGHT: bold"></SPAN></FONT> </DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN style="FONT-WEIGHT: bold">So you
send key presses reliably, and then wait for the server to respond back with a
new state? What happens if a player fires their weapon, for instance, is this
sent reliably? I guess my main confusion is what should and what should not be
reliable traffic. It would make sense to me that gunshots were reliable, where
as individual movement steps could be sent unreliably as you say. Now let's say
that the client takes a step, do you then render the movement animation
immediately before you get the response back from the server and then correct it
if the server refuses, or do you wait for the server to accept the move? If the
former, what happens if the client moves but he's not allowed to, do you just
silently bounce him back? If the latter, wouldn't there be a noticeable delay
between the key press and the actual movement since we need at least one
roundtrip for that?</SPAN></FONT></DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN
style="FONT-WEIGHT: bold"></SPAN></FONT> </DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN style="FONT-WEIGHT: bold">Kind
regards,</SPAN></FONT></DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN
style="FONT-WEIGHT: bold"></SPAN></FONT> </DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN style="FONT-WEIGHT: bold">Philip
Bennefall</SPAN></FONT></DIV>
<DIV><FONT size=3 face="Times New Roman"><SPAN
style="FONT-WEIGHT: bold"></SPAN></FONT>----- Original Message ----- </DIV>
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<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=nick@lifebloodnetworks.com
href="mailto:nick@lifebloodnetworks.com">Nicholas J Ingrassellino</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=enet-discuss@cubik.org
href="mailto:enet-discuss@cubik.org">Discussion of the ENet library</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, November 24, 2010 6:23
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [ENet-discuss] Best
practises for synchronizing states</DIV>
<DIV><BR></DIV>I question if the lag is as bad as you are expecting it to be.
Some connections and/or rural areas are worst than others but I am not sure it
will be as bad as you think. For example, if you look back at the last few
e-mails I sent to this list you will see my current project treats the client
as a dumb terminal-- only key presses are send and object information is back
unreliably 20 times a second. There is some dead reckoning (the object speed
and direction are sent to the client and the client does that work while
waiting for the next update) and I do not have an issue even on my mobile
phone.<BR><BR>My point is you should run a number of tests to see what you
get. Make sure to play with the rate the "server" (or in your case client to
client) sends data vs bandwidth usage. Make sure you do not flood the line
with too many tiny packets and that you process all packets in a while loop
(vs an if) to make sure you processes everything as fast as possible. Another
note on my project is that I do not wait on an timers to process network
events (as opposed to my log and display code that only happens 60 times a
second).<BR><BR>I think you may surprised yourself with what you can pull off
in terms of latency.<BR>
<DIV class=moz-signature><BR>
<HR style="HEIGHT: 1px">
<P><SPAN style="FONT-WEIGHT: bold">Nicholas J Ingrassellino<BR><A
style="TEXT-DECORATION: none" href="http://www.lifebloodnetworks.com/"
target=_blank>LifebloodNetworks.com</A></SPAN> || <A
style="TEXT-DECORATION: none"
href="mailto:nick@lifebloodnetworks.com">nick@lifebloodnetworks.com</A></P>
<P style="FONT-SIZE: 75%">"<SPAN style="FONT-STYLE: italic">The idea that I
can be presented with a problem, set out to logically solve it with the tools
at hand, and wind up with a program that could not be legally used because
someone else followed the same logical steps some years ago and filed for a
patent on it is horrifying.</SPAN>"<BR>- <SPAN style="FONT-WEIGHT: bold">John
Carmack</SPAN> on software patents</P></DIV><BR>On 11/23/2010 10:00 PM, Philip
Bennefall wrote:
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<DIV><FONT size=2 face=Arial>Hi all,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>This is a fairly lengthy email, so I apologize
in advance.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>I am relatively new to ENet. I have integrated
it in my game engine and have successfully written a game which is working
perfectly. It is one of those finger twitching action games where speed is
of the utmost importance and delay is the most evil thing in the world. The
way I do it is to keep sending the entire state for a player to the other
party unreliably. The other client then works out the events that "must"
have occured by looking at the differences between the last known state and
the new one. This is far from a perfect solution as it neither scales well
nor provides for very readable code. Here's a summary of how I'm handling
things:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>The game is a shooter where you run a round on
a 1d grid firing rocks at your oponent's palace. When a rock hits a square
on the other side it'll quickly begin piercing its way through until
that section of the wall crumbles. During that time, the other player may
use their hammer to defend the section.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>I wrote an internal layout description for
myself before I started coding, which I then followed to ensure proper
handling of all possible situations.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>---Start of Internal
Description---</FONT></DIV>
<DIV><FONT size=2 face=Arial>The way in which this game communicates over
the network is fairly simple. The two players have a direct connection
established between one another, and they send out their player state
roughly 30 times a second. This player state contains the current x
position, the current throwing position which is -1 if nothing is being
thrown, and then a list of all the squares on that player's side. For each
square, two values are stored. The first is the current resistance which is
20 on max, and 0 if the square is destroyed. The second one is crumbling
speed which is 0 if the square is not currently crumbling, and a value in
milliseconds otherwise. This value is used to measure if two or more rocks
have been thrown on the same square.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>When a new state is received from the remote
player, we have to analyse this information in order to determine what
changes that have occured and if we need to take any action.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>If a new x position is received, we simply move
the player's local variable to this square and play a footstep
sound.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>If the new throwing position is different from
our old one, we can take a few actions depending on its value:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>1. If the new one is greater than -1 and the
old one is -1, the remote player threw a rock at us. we play the throwing
sound in the appropriate location, but take no other action.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>2. If the new one is -1 and the old one is
greater than -1, we can assume that the remote player hit us and start the
crumbling sequence for that square on our end. Naturally if our square is
already crumbled, the remote player will not get any hit notifications from
us. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>3. If they both are greater than -1, we can
assume that the remote player hit us and so we activate that sequence as
above. We can also assume that the remote player made a new throwing attempt
in another location and that we didn't see the -1 state that came prior to
it probably because of lag, and so we play another throwing sound in the new
location.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>After this, we go on to scan the game board and
do the following for each square:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>If the new resistance is greater than the old
one, the remote player hammered and so we play that sound.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>If the new resistance is lower than the old
one, we can take four actions.</FONT></DIV>
<DIV> </DIV><FONT size=2 face=Arial></FONT>
<DIV><FONT size=2 face=Arial><BR>1. If the new resistance is 0 and the old
resistance is greater than 0, the square just broke so we play the
appropriate sound and forget about it.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>2. If the old crumbling speed is the same as
the new one, this was a normal crumbling step and so we play the appropriate
sound.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>3. If the old crumbling speed is 0 and the new
one is greater than 0, this was a new hit so we react
accordingly.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>4. If the old one is greater than the new one
and the new one is greater than 0, this was a new hit on the same
square.<BR></FONT><FONT size=2 face=Arial>---End of Internal
Description---</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>I realize that this is a lot of very game
specific information, and that's exactly my point. This all seems like a
very dirty hack to me, and I was wondering if any of you can suggest a
better and more scalable way of doing this while still keeping latency to an
absolute minimum?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Thanks in advance for any help!</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Kind regards,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Philip Bennefall</FONT></DIV>
<DIV><FONT size=2 face=Arial>P.S. I should perhaps mention that this is a
game for the blind; entirely based on sound, which is why sounds are
mentioned all over the place rather than graphics.</FONT></DIV><PRE wrap=""><FIELDSET class=mimeAttachmentHeader></FIELDSET>
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