TheGameCreators - CodeBase - Multiplayer Example from Connection to Gameplay

Category: Multiplayer

Version: 1.0

Information

Uploaded: 27th Sep 2004 07:36

Modified: 1st Jan 1970 01:00

Author: Richard Davey

Summary

To accompany the article in Issue 21 of the newsletter. This is a complete multiplayer routine illustrating a text chatbox and gamestate written by Shawn Bower of Starwraith 3D Games LLC.

Full Description

DarkBASIC Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

rem Multiplayer Example from Connection to Gameplay

rem by Shawn Bower of StarWraith 3D Games (starwraith3dgames@att.net)

rem                   www.starwraith.com

rem A complete multiplayer routine illustrating a text chatbox and gamestate

rem Provided free for use in your projects (commercial or otherwise).

rem You're welcome to modify and use this code however you wish.

rem A short credit in your project indicating where you got the core

rem code from is appreciated, but not required.

rem I do ask that you please provide me with a copy of the project you

rem use this code in as I like to see what others come up with.

rem _____________________________________________________

rem This was designed on and intended for use with DarkBasic 1.13 with

rem the enhancement pack, it has not been tested with other versions.

rem I've tried to make the code easy to understand and relatively

rem modular so you can cut and paste sections of it for easy implementation

rem into your projects.  It's designed around a line by line style with

rem comments to help make it easier to understand what is being done.

rem A lot of integrity checks are in this example also.

rem _____________________________________________________

rem To use this example, the host should start a session first and make

rem sure the correct IP address is used, or the client won't be able

rem to find the game and they will just automatically start another

rem session on whatever IP they enter.

rem This basic example does not include things like packet rate throttling

rem or sophisticated movement prediction, it merely illustrates how to

rem design a chat room for your game and monitoring gamestate for player

rem objects.  This example does not require any external media, it is

rem designed to work as stand-alone, so you can just hit F5 and run it.

rem Note: there are many ways to accomplish the same routines, this is

rem just an example to illustrate the concept.  It's design is for

rem simplicity, not efficiency or complexity.

rem _____________________________________________________

rem Remember that IP addresses can be blocked by routers or firewalls,

rem so if you're trying to get this to work over the internet using

rem broadband connections, you may need to open ports or use a DMZ

rem Refer to your router or firewall's documentation on how to do this.

rem Using a DMZ or opening ports can reduce the security for your

rem network/internet connection, so you do so at your own risk.

rem _____________________________________________________

rem Using this as a foundation, you can further enhance multiplayer for

rem your project with movement prediction to smooth out the motion and

rem reduce jerkiness.  You can do this by measuring how far a player

rem moves between packets, then predict the same movement prior to receiving

rem the next packet.  Doing this for rotations also will further smooth the

rem overall movement and accuracy of gameplay.

rem You can use these same concepts for all needed weapon data and can

rem add such data to the existing data packet to keep things simple.

rem For more detailed instructions, refer to the Multiplayer Tutorial I

rem wrote (contact me if you'd like a copy in HTML format).

rem You can use the Window mode settings below if you want to

rem compile and run this example in a window to test multiple copies

rem of it on your local IP address.  You can alt-tab between them as

rem needed and space them across a 1280X960 or larger desktop.

rem set window on:always active on

rem __________________BEGIN MULTIPLAYER EXAMPLE_________________

rem set a few display parameters

rem use sync

sync on

rem overstep sync rate by two for consistent performance (30+2)

sync rate 32

rem set black backdrop and no camera tracking when creating objects

backdrop on

color backdrop 0

autocam off

draw to front

set text font "arial"

set text size 12

set text transparent

set camera range 1,3000

hide mouse

rem DIM a few variables we will need to use

dim mpgot(10)

dim zchat$(20)

rem **** SET THE MULTIPLAYER VARIABLES

rem use the 'packetrate' variable for a set packet exchange rate

rem you can check for ping rates or exchange rates and throttle this

rem setting on the fly to reduce lag or poor performance

rem this is in milliseconds, 250 means 4 packets per second, ok for internet

rem gameplay with a few players

packetrate=250

rem **** CREATE GAME WORLD

rem Let's create a small world for our game to take place

rem first a nice blue background sky sphere

rem draw all 2D graphics used for textures off-screen to boost speed

create bitmap 1,256,256

set current bitmap 1

for i = 0 to 127

ink rgb(i,i*2,255),0

line 0,i,256,i

next i

ink rgb(127,255,255),0

for i = 128 to 256:line 0,i,256,i:next i

get image 1,0,0,256,256

cls

rem now some simple terrain

ink rgb(128,170,0),0

for i = 0 to 256:line 0,i,256,i:next i

for i = 0 to 5000

s=130+rnd(80)

ink rgb(s-42,s,0),0

dot rnd(255),rnd(255)

next i

get image 2,0,0,256,256

delete bitmap 1

set current bitmap 0

rem now that we've got the textures, create the environment objects

make object sphere 1,1000

texture object 1,1

set object 1,1,1,0,1,0,0

make object plain 2,2000,2000

texture object 2,2

scale object texture 2,10,10

xrotate object 2,90

position object 2,0,-20,0

set ambient light 100

rem now create 8 objects to represent 8 players

rem low number players will be blue boxes which fade to

rem red with higher number players

for i = 0 to 7

make object cone 10+i,5

color object 10+i,rgb(i*30,0,210-(i*30))

xrotate object 10+i,90

fix object pivot 10+i

rem make sure to hide player objects not in use

hide object 10+i

next i

rem make sure the camera is in the center of the world

position camera 0,0,0

rem **** FIND THE TCP/IP CONNECTION TYPE

rem sample code to setup a net connection

perform checklist for net connections

sync:sleep 50

netsel=0

nettotal=checklist quantity()

for a = 1 to nettotal

rem find the connection for TCP/IP internet

if checklist string$(a)="Internet TCP/IP Connection For DirectPlay" then netsel=a

next a

rem if TCP/IP wasn't found and netsel=0, which can occur on non-english

rem versions of windows, set the netsel variable to the last detected

rem connection type which is almost always TCP/IP anyway

if netsel=0 then netsel=nettotal

rem if no connections detected and netsel still equals 0, stop the program

if netsel=0 then end

rem **** USE WHATEVER ENTRY ROUTINE TO LET THE PLAYER SELECT THE IP ADDRESS

rem now let the player enter the IP address they want to use

ask4ip:

ky$=entry$()

if ky$="" then goto msync0

clear entry buffer

if right$(ky$,1)=chr$(13) then add$=chat$:chat$="":goto gotip

if right$(ky$,1)=chr$(8) then chat$=left$(chat$,len(chat$)-1):ky$=""

if len(chat$)>30 then ky$="":goto msync0

chat$=chat$+ky$

ky$=""

msync0:

ink rgb(255,255,255),0

text 10,10,"Enter IP address to connect to: "+chat$+"_"

sync

goto ask4ip

gotip:

sleep 500

ky$=""

rem now let the player select the name they want to use

ask4name:

ky$=entry$()

if ky$="" then goto msync1

clear entry buffer

if right$(ky$,1)=chr$(13) then goto gotname

if right$(ky$,1)=chr$(8) then playername$=left$(playername$,len(playername$)-1):ky$=""

if len(playername$)>10 then ky$="":goto msync1

playername$=playername$+ky$

ky$=""

msync1:

ink rgb(255,255,255),0

text 10,10,"IP Address selected: "+add$

text 10,20,"Enter the name you want to use: "+playername$+"_"

sync

goto ask4name

gotname:

rem **** ESTABLISH MULTIPLAYER CONNECTION

rem now establish the connection using the connection type and IP address

for i = 0 to 5

text 10,50,"Establishing connection to: "+add$

sync

next i

set net connection netsel,add$

for i = 0 to 5

text 10,70,"Connection established..."

sync

next i

rem **** NOW SCAN THE CONNECTION FOR EXISTING GAMES

rem check for active games on the IP address the player just connected to

perform checklist for net sessions

if checklist quantity()<1 then game$="None":goto nogame

game$=checklist string$(1)

nogame:

rem if a game doesn't already exit, let the player host

rem otherwise, joining the existing game is the only option

rem NOTE: you can hault the process here to let the player select

rem from a series of active games, or manually start hosting

rem this example just automates the process based on what is detected

if game$="None" then goto setashost

for i = 0 to 30

text 10,85,"Active session detected on this IP..."

text 10,100,"Joining active session as client..."

sync

next i

join net game 1,playername$

rem now send a greeting message that a new player has joined

rem this example will use MESSAGE= as a flag for a text message for the

rem chat sequence of this multiplayer routine

rem send messages three times to make sure it gets through

rem using the 0 flag will send the message to all players

for i = 0 to 2

send net message string 0,"MESSAGE="+playername$+" has joined the game!"

sync

next i

cls

rem get general timer for exchange rate

tmm=timer()

oldtmm=tmm

goto multimain

setashost:

rem if game$="None" then this section starts a new game on this IP address

rem The 8 is the maximum number of players, 1 is for peer-to-peer

rem client/server is another connection option which routes all data

rem traffic through the host's computer instead of letting each player's

rem system talk directly to every other player's system

for i = 0 to 70

text 10,85,"No session detected on this IP..."

text 10,100,"Creating multiplayer session as host..."

sync

next i

create net game "Multiplayer Game #1",playername$,8,1

cls

tmm=timer()

oldtmm=tmm

multimain:

ink rgb(255,255,255),0

text 300,0,"Use Arrow keys to move around..."

text 300,20,"Type text messages and press enter to send..."

rem get a continuous list of all players

text 10,10,"Current players:"

perform checklist for net players

totalplayers=checklist quantity()

for i = 1 to totalplayers

rem now save each player's unique ID number to the MPGOT array

rem to help keep track of each specific player more accurately

mpgot(i-1)=checklist value b(i)

rem grab the name of each player in the session

name$=checklist string$(i)

rem if name on the list matches this player, get the unique ID number as

rem we'll need it later for transmitting packets

if name$=playername$ then playernum=checklist value b(i)

rem display each name in the upper left of the screen

text 10,10+(i*10),name$

next i

rem display any messages in the chatbox queue

for i = 0 to 13

text 10,200+(i*10),zchat$(i)

next i

rem rpackets is how many packets we're receiving this cycle, if we receive

rem a packet, we want to skip sending a packet for this sync.  this helps

rem reduce packet overload and the resulting lag.

rpackets=0

rem check for disconnect, exit as needed

if net game lost()=1 then for i = 0 to 90:text 10,450,"Connection lost...":sync:next i:end

rem search/scan for new messages

keepchecking:

get net message

message$=net message string$()

rem if no net message received, then leave scan routine

if message$="" then goto scrappacket

rem if a message is detected, apply it to the chatbox array line by line

if left$(message$,8)<>"MESSAGE=" then goto notamessage

mess$=right$(message$,len(message$)-8)

rem if it is a duplicate message, just discard

if zchat$(13)=mess$ then goto scrappacket

rem if it's a new message, scroll the chatbox and add the message

for i = 0 to 12:zchat$(i)=zchat$(i+1):next i

zchat$(13)=mess$

rem add one to the received packets variable to indicate we got one

rpackets=rpackets+1

goto baddata

notamessage:

rem **** DATA PACKET RECEIVE ROUTINE

rem lets assign this data packet to a shorter variable, pc$

pc$=message$

rem DECODE MULTIPLAYER PACKET

rem we'll use decod for the character position when analyzing the packet

rem start at the first character

decod=1

rem we'll use plyr$ for the player ID number

rem mx$, my$, and mz$ will be used to store the player's position

rem max$, may$, and maz$ will be used to store the player's rotation angles

rem angle Z is included in this example, but isn't required

rem reset variables to null values every time a packet is received

plyr$="":mx$="":my$="":mz$="":max$="":may$="":maz$=""

rem this routine will scan each packet character until the seperator

rem character is encountered.  Once the seperator is encountered, the

rem variable has been stored and is ready for use.  We'll use "|" as

rem the seperator in our packet structure.  The first step is

rem to get the player ID number this packet is for:

getplayernum:

mpp$=mid$(pc$,decod)

if mpp$="|" then goto setmvplyr else goto nomvplyr

setmvplyr:

decod=decod+1

rem we'll use mvplyr to indentify which player slot this packet is for

mvplyr=-1

for i = 1 to totalplayers

rem now compare the plyr$ result with the numbers we stored in the

rem mpgot array.  Find the one is matches, then identify who the

rem packet is for using the mvplyr variable (will be in the 0-7 range)

rem make sure to stick to string values, if you try to convert the

rem plyr$ variable to a number using val(), you will encounter mismatches

rem because the result can get reduced by several digits.  You can convert

rem large numbers stored in non-string variables to strings, but you

rem can't go the other way without risking inaccurate results.

if plyr$=str$(mpgot(i-1)) then mvplyr=i-1

next i

rem since we received a data packet, add one to our rpackets counter

rpackets=rpackets+1

rem now that we have the player number, continue analyzing the rest of the

rem packet starting with the X position (saved to mx$) of the player

goto getmx

nomvplyr:

plyr$=plyr$+mpp$

decod=decod+1

goto getplayernum

getmx:

mpp$=mid$(pc$,decod)

if mpp$="|" then decod=decod+1:goto getmy

mx$=mx$+mpp$

decod=decod+1

goto getmx

getmy:

mpp$=mid$(pc$,decod)

if mpp$="|" then decod=decod+1:goto getmz

my$=my$+mpp$

decod=decod+1

goto getmy

getmz:

mpp$=mid$(pc$,decod)

if mpp$="|" then decod=decod+1:goto getmax

mz$=mz$+mpp$

decod=decod+1

goto getmz

getmax:

mpp$=mid$(pc$,decod)

if mpp$="|" then decod=decod+1:goto getmay

max$=max$+mpp$

decod=decod+1

goto getmax

getmay:

mpp$=mid$(pc$,decod)

if mpp$="|" then decod=decod+1:goto getmaz

may$=may$+mpp$

decod=decod+1

goto getmay

getmaz:

mpp$=mid$(pc$,decod)

if mpp$="|" then decod=decod+1:goto gotvariables

maz$=maz$+mpp$

decod=decod+1

goto getmaz

gotvariables:

rem Now position the identified player's object where it needs to be

if mvplyr=-1 then goto baddata

mppx#=val(mx$)

mppy#=val(my$)

mppz#=val(mz$)

mpmx#=val(max$)

mpmy#=val(may$)

mpmz#=val(maz$)

position object 10+mvplyr,mppx#,mppy#,mppz#

rotate object 10+mvplyr,mpmx#,mpmy#,mpmz#

rem if we receive a packet for a player not currently visible, show object

rem if a player leaves, you can detect that event and hide the object

if object visible(10+mvplyr)=0 then show object 10+mvplyr

baddata:

rem then check for any remaining messages

if net message exists()=1 then goto keepchecking

scrappacket:

rem monitor any chat messages the player enters to broadcast to other players

text 10,400,">"+chat$+"_"

ky$=entry$()

if ky$="" then goto msync2

clear entry buffer

if right$(ky$,1)=chr$(13) then chatb$=chat$:chat$="":broadcast=3:goto msync2

if right$(ky$,1)=chr$(8) then chat$=left$(chat$,len(chat$)-1):ky$=""

if len(chat$)>55 then ky$="":goto msync2

chat$=chat$+ky$

ky$=""

msync2:

if broadcast=0 or rpackets>0 then goto skipbroad

tmm=timer()

if tmm<oldtmm+packetrate then goto nodatapacket

rem send message packet 3 times to make sure it gets delivered

send net message string 0,"MESSAGE="+chatb$

rem now on the last send, add this message to the chatbox as needed

if broadcast=1 then for i = 0 to 12:zchat$(i)=zchat$(i+1):next i:zchat$(13)=chatb$

broadcast=broadcast-1

oldtmm=timer()

goto nodatapacket

skipbroad:

rem **** SEND DATA PACKET ROUTINE

rem if no message is being sent, send data packet instead

rem you can also just send a data packet right after a message packet,

rem just wait until after the next sync before doing so.

rem this also runs a slightly higher risk of causing lag, but maintains

rem gamestate data a little better at low exchange rates

tmm=timer()

rem if the packetrate time hasn't been reached yet, delay sending data

rem to prevent overloading the connection and causing lag

if tmm<oldtmm+packetrate or rpackets>0 then goto nodatapacket

rem now generate a data packet with this player's position and

rem rotation using the | character as a seperator for the variables

pc$=str$(playernum)+"|"

pc$=pc$+str$(camera position x())+"|"

pc$=pc$+str$(camera position y())+"|"

pc$=pc$+str$(camera position z())+"|"

pc$=pc$+str$(camera angle x())+"|"

pc$=pc$+str$(camera angle y())+"|"

pc$=pc$+str$(camera angle z())+"|"

send net message string 0,pc$

oldtmm=timer()

nodatapacket:

rem allow the player to move around using the arrow keys

if upkey()>0 then move camera 0.4

if downkey()>0 then move camera -0.4

if rightkey()>0 then yrotate camera wrapvalue(camera angle y()+2)

if leftkey()>0 then yrotate camera wrapvalue(camera angle y()-2)

rem recenter sky sphere

position object 1,camera position x(),camera position y(),camera position z()

rem now we're ready to update the gamestate and refresh the screen

sync

goto multimain

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Author Name:	Richard Davey
CodeBase Entries:	57

CodeBase - Multiplayer Example from Connection to Gameplay

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DarkBASIC Source Code

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