isnake_kucc2008_report.pdf

ProjectReport

on

iSnakeMultiplayerIntelligentSnakeGamehttp://isnake.sourceforge.net

Submittedto

InterCollegeUndergraduateProjectCompetition

KUCCSoftwareMeet2008

Mar.7,2008

by

AbhishekDutta JitendraHarlalka SurajSapkota

[email protected] [email protected] [email protected]

cell:9841559669 cell:9803395335 cell:9841579381

TableofContents

1 Acknowledgment..................................................................................................................................1 2 Abstract.................................................................................................................................................2 3 Objectives.............................................................................................................................................3 4 Programming Environment...................................................................................................................4 5 Methodology.........................................................................................................................................5

5.1 iSnake Client Application..............................................................................................................6 5.1.1 Client Encoder/Decoder.........................................................................................................6 5.1.2 Client Network Interface........................................................................................................6 5.1.3 Input Handler..........................................................................................................................6 5.1.4 Game Field Matrix.................................................................................................................7 5.1.5 Game Field Canvas.................................................................................................................7 5.1.6 User Interface Components....................................................................................................7 5.1.7 Game Controller.....................................................................................................................7

5.2 iSnake Game Server......................................................................................................................8 5.2.1 Server Encoder/Decoder.........................................................................................................8 5.2.2 Server Network Interface........................................................................................................8 5.2.3 Virtual Game Field.................................................................................................................9 5.2.4 Player Information Manager...................................................................................................9 5.2.5 Random Number Pool............................................................................................................9 5.2.6 Status Server...........................................................................................................................9 5.2.7 Server Core...........................................................................................................................10

5.3 Intelligent Autonomous Opponent Snakes..................................................................................10 5.4 iSnake Game Server Manager (GSM) @ SF.net.........................................................................13

6 Project Management...........................................................................................................................14 7 Documentation....................................................................................................................................16 8 Limitations..........................................................................................................................................16 9 Future Enhancements..........................................................................................................................17 10 Conclusion........................................................................................................................................17 11 References.........................................................................................................................................18 12 ANNEX A: Blackmamba path finding algorithm 13 ANNEX B: Viper path finding algorithm 14 ANNEX C: Program Flow 15 ANNEX D: Inter Snake Communication Protocol (ISCP)

1 Acknowledgment

WeoffergratitudetoprojectsupervisorAsst.Prof.JayaramTimsina(DeputyHOD,Dept.Of

Electronics&ComputerEngineering,IOEPulchowkCampus)forguidingusthroughoutthe

project.

We would like to thank all those forum members at JavaGaming.org

[http://www.javagaming.org]andSunJavaForum[http://forum.java.sun.com] whoreplied

toourendlessquerieswithoutanycomplain.

We acknowledge the creators of Quantum Random Bit Generator Service [QRBG

http://random.irb.hr],whichprovidesourgameserverwithhighqualityrandomnumbers.

1

2 Abstract

Thisprojectaimstobringthefunandsimplicityofsnakegamewithsomenewfeatures.Itwill

includecomputercontrolledintelligentopponentswhoseaimwillbetochallengethehuman

players.Itwillalsohavethemultiplayerfeaturethatwillallowmorethanoneplayerstoplay

thegameoveranetwork.

This project explores a new dimension in the traditional snake game to make it more

interestingandchallenging. Thesimplicity of this gamemakes it anideal candidatefora

minor project as we can focus on advanced topics like multiplayer functionality and

implementationofcomputercontrolledintelligentopponents.

2

3 Objectives

Thisgameaimstochangethewaypeoplethinkoftraditionalsnakegame.Itwillofferthe

experienceofcommercialmultilayergamestotheplayerretainingthesimplicityoftraditional

snakegame.

Themajorobjectivesofthisprojectare:

Createasnakegamethatwillhaveallthefunctionalityoftraditionalsnakegames.

Introducemultilayerfunctionalityinthegamethatwillallowseveralplayerstoplaya

gamesimultaneously.Itshouldbeabletogivetheexperienceofarealtimemultiplayer

gametotheplayers.

Introducecomputercontrolledintelligentopponent(uniquefeatureofthisgame)to

makethegamemorechallengingandinteresting.Themovementandactionofthese

intelligentopponentswillbecontrolledbycomputerwhoseaimwillbetoeatthefood

beforehumanplayerscaptureit.

3

4 ProgrammingEnvironment

Weusedseveralopensourcetoolstodevelopthisproject:

Netbeans5.5IDE

All the developers of iSnake teamused Netbeans IDE for the development of this

project.

Inkscape0.45andGimp2.2

ThesegraphicsdevelopmenttoolswereextensivelyusedforthedevelopmentofUser

Interfacecomponents.Theillustrationspresentedinthisreporthavealsobeenprepared

usingtheseopensourcetools.

Gnuplot

Thedataobtainedduringprofilingoftwopathfindingalgorithmsviz.Blackmambaand

Viperwasplottedusinggnuplot.

OpenOfficeWriter2.2

AlltheprojectdocumentsandthisreportwerepreparedusingOpenOfficeWriter2.2.

WiresharkNetworkTrafficAnalyzer0.99.6

DuringthedevelopmentofiSnakeGameServerManager(GSM)@SF.net,Wireshark

toolwasusedtoanalyzethenetworktraffic.

4

5 Methodology

iSnakeisamultiplayerversionoftraditionalsnakegame(popularamongcellphonegamers)

withcomputercontrolledintelligentopponentsthatchallengesthehumanplayers.

Theplayerwhohoststhegameserveriscalledlocalplayer.TheiSnakeClientApplication

andGameServerruninseparateexecutiondomains.TheiSnakeClientApp.forlocalplayer

communicateswiththegameserverthroughnetworklayer,justlikeotherremoteplayers,as

showninillustration1.

ThecompleteiSnakeapplicationisdividedintofourmajorcomponents:

iSnakeClientApplication

iSnakeGameServer

IntelligentAutonomousOpponentSnakes

iSnakeGameServerManager(GSM)@SF.net

5

Illustration 1: iSnake block diagram

5.1 iSnakeClientApplicationiSnakeclientapplicationreferstotheapplicationusedtoplaysnakegame.Aplayerjoins

analreadyexistingiSnakegameserverusingthisapplication.

ThemaincomponentsofiSnakeClientapplicationare:

5.1.1 ClientEncoder/Decoder

Thismoduleperformstheencodinganddecodingofmessagesleaving/arrivingthe

clientnetworkinterfacemoduleusingtheprotocolstandarddescribedinANNEXD:Inter

SnakeCommunicationProtocol.

5.1.2 ClientNetworkInterface

ItprovidesaninterfacetotheGameControllermoduleforcommunicationwiththe

game server hosted at local/remote computer. It is responsible for triggering of

appropriatemethodsofGameControllerwhenmessagefromGameServerisreceived.

5.1.3 InputHandler

Itmanagesthetaskofsamplingkeystrokesfromlocalplayerandforwardingitto

GameControllerwhenrequested.Itmaintainsaqueueofsize2sothatquickkeystrokes

arenotlost.Itisactiveonlywhenthegameisinrunningmode.

6

Illustration 2: Block diagram of iSnake Client Application

5.1.4 GameFieldMatrix

GameControllermaintainsthecompletestateofthegameusinggamefieldmatrix.

Itisa2Darrayofsize58x58(equaltothegamefielddimensions).Eachgamefieldobject

hasauniqueidentifierinthegamefield.GameControllerupdatesthecellsofthismatrix

ineachcycletoregisterthechangesthatoccurinthegame.

5.1.5 GameFieldCanvas

Itrepresentsthegamefieldasseenbytheplayer.GameControlleranalyzesthe

gamefieldmatrixineachcycleandupdatesthegamefieldcanvastorepresentthestateof

gameinthatgamecycle.DoubleBuffering[usingjava.awt.Canvas.createBufferStrategy()]

hasbeenimplementedtoavoidflickeringofgamefield.Eachblockinthegamefieldhas

dimension10x10pixels.

The update of game field canvas occurs in the way similar to the refreshing

techniqueofacathoderaymonitor.Thegamefieldmatrixandgamefieldcanvasare

updated in separate thread. Theupdateof game field canvas starts byscanningeach

columnofthe1strowinthegamefieldmatrix,then2ndrowandsoonuptothe58throw.

Thegamefieldisrefreshedtwiceduringeachgamecycle(tworefreshcycleforgamefield

canvas for each game cycle). This is done make the movements in the game field

smoother.

5.1.6 UserInterfaceComponents

Thismoduleincludesallthecomponents,exceptgamefield,visibletotheplayer.

Thelookandfeelofdefaultswingcomponentshavebeenoverriddentogivethefeelofa

game to the players. MIT OCW's course1 [6.831] User Interface Design and

Implementationwasveryhelpfulduringdesignofmostoftheuserinterfacecomponents

ofthisgame.

5.1.7 GameController

ItisthemostimportantcomponentoftheiSnakeclientapplication.Itcoordinates

theworkingof all theothermodules in theapplicationandhandles all themessages

1 See References [Website]

7

receivedfromthegameserver.GameControllermaintainsthegamecyclewhenthegame

isrunning.Thisgamecycleissynchronizedwiththegamecycleofthegameserver.Allthe

updatestogamefieldmatrixaredoneduringthiscycletime.Afterexpiryofeachgame

cyclethegamefieldisrepaintedtoreflectthechangesinthegamefield.

5.2 iSnakeGameServeriSnakegameserver handles the multiplayer feature of this gameandallows multiple

iSnakeclientapplicationstoplaythegamehostedbythatparticulargameserver.

ThemaincomponentsofiSnakeGameServerare:

5.2.1 ServerEncoder/Decoder

Thismoduleperformstheencodinganddecodingofmessagesleaving/arrivingthe

servernetworkinterfacemoduleusingtheprotocolstandarddescribedinANNEXD:Inter

SnakeCommunicationProtocol.

5.2.2 ServerNetworkInterface

It providesaninterfaceto theServerCoremodule for communicationwiththe

remote/local players of the game being hosted. It is responsible for triggering of

appropriatemethodsofServerCorewhenmessagefromremote/localplayersisreceived.

8

Illustration 3: Block diagram of iSnake Game Server

5.2.3 VirtualGameField

Gameservermaintainsthestateofthegameusinga2Darrayofsize58x58(similar

tothatusedbyGameControllerreferto5.1.4).

Itismaintainedbythegameservertocheckwhetherthefoodhasbeeneatenand

whetheranyplayerhascollidewiththewall.Itmaintainstheheadcoordinate(notthe

coordinatesfortails)ofeachplayer.Theheadcoordinateofplayersismovedineachgame

cycleandcheckedforthepresenceofwall/foodinthatcoordinateposition.ServerCore

generates corresponding event (collide or food eaten) and all the active players are

informedabouttheeventinthesamecycle.

5.2.4 PlayerInformationManager

It manages the information about the players involved in the game. Player

information like name, location, score, snake's starting position, snake color, etc are

maintained.Anewentryisaddedwheneveranewplayerjoinsthegame.Similarly,when

theplayerleavesthegame,itisremoved.

5.2.5 RandomNumberPool

Game server maintains a buffer of random numbers obtained from Quantum

RandomBitGeneratorservice[QRBGhttp://random.irb.hr].Thisgivesthegameserver

accesstotruerandomnumber.Theserandomdataisusedtogeneratethepositionoffood

andthestartingcoordinateofeachplayer'ssnake.

If the random number service is unreachable pseudo random numbers are

generatedusingjava.util.RandomclassprovidedbyJava.

5.2.6 StatusServer

Statusservermaintainsalltheinformationrequiredtoreplythecurrentstatusof

the game server. The service of status server is utilized by iSnake Game Server

Manager(iSnakeGSM)2hostedathttp://isnake.sf.net.Theresponseofstatusserverisa

wellformedXMLdocumentthatisparsedbyiSnakeGSMtodisplayinformationabout

thegameserverinthewebsite.

2 Refer to 5.4 iSnake Game Server Manager (GSM) @ SF.net

9

AtypicalresponseofStatusServerisgivenbelow:

124.41.228.219

9669

5

Waiting

5.2.7 ServerCore

ItisthemostimportantcomponentoftheiSnakeGameServer.Itcoordinatesthe

workingofalltheothermodulesintheapplicationandhandlesallthemessagesreceived

fromtheremoteplayers.

When the game is in "Waiting" mode, Server Core provides the facility of chat

messagingtothegameplayers.Duringthisstatenewplayerscanjointhegame.

Whenalltheplayershavesentsignaltostartthegame,theServerCorechanges

state to Running mode. If a newplayer tries to join the game, it receives a NAK

response.Inthismode,ServerCoremaintainsagamecycletimeduringwhichitreceives

themovementcoordinates(intermsofdeltaXanddeltaY)fromtheplayers.Ifaplayer

doesnotsendanypacketduringthiscycletime,serverconsidersthemovementcoordinate

sent in last cycle for thecurrentgamecycle. Afterexpiryofcycle time, gameserver

broadcastsapacketcontainingmovementcoordinatesofeachplayertoall theplayers

activeinthegame.Thegameserveralsochecksifanyplayerhaseatenthefoodorifany

playershavecollidedtothewallineachcycle.

5.3 IntelligentAutonomousOpponentSnakesThesearecomputercontrolledsnakes,inthegame,whoseaimistochallengethe

human players. We have two implementations of path finding algorithms to create

intelligentautonomousopponentsnakes. Thesealgorithmsreturntheshortest possible

10

pathfromgivensource(S)andtarget(T)coordinatepairconsideringtheobstacles(if

any)presentinthegamefield.Thecodename3forthesetwoimplementationsare:

Blackmamba(refertoANNEXA)

Viper(refertoANNEXB)

Adetailed paper describingthealgorithmusedby these two implementation is

presentin ANNEXAandANNEXB.Themoduleimplementingthesetwopathfinding

algorithmeasily fits into theexistingdesignof iSnakeClient Applicationas shownin

Illustration4

Toknowwhichof the two implementations performbetter, weprofiled themusinga

simpleJUnittestandtheresultswereplottedusinggnuplot:

3 Named after two popular species of venomous snakes

11

Illustration 4: Module implementing two path finding algorithms replaces the Input Handler module of standard iSnake Client application.

Illustration 6: Length of path returned by the two path finding algorithms

Turnaroundtimeplot

Thetimeelapsedbetweentheinstantofsupplyingthe(source,target)coordinate

pair(S,T)tothealgorithmandtheinstantwhenitreturnsapathforsupplied(S,T)pairis

calledturnaroundtime.Fromtheplotofillustration5,itisclearthattheturnaround

timeforViperisalwayssmallerascomparedtoBlackmamba.

PathLengthplot

Thelengthofpath(computedbycountingthenumberofgamefieldcoordinatesin

the path) returned by the two path finding algorithms is depicted by the plot of

illustration6.ItisclearfromtheplotthatViperimplementationresultsinsmallerpaths

(andhenceefficient)ascomparedtoBlackmambaimplementation.

NOTE:Thevalueofturnaroundtimeandpathlengthforthecoordinatepairs5,7,8have

negativevaluesforBlackmamba.Thissuggeststhatthealgorithmwasnotabletocomputea

pathforgiven(S,T)pairingiventimeoutperiod(250msforthistest).

12

Illustration 5: Turn around time for two path finding algorithms

5.4 iSnakeGameServerManager(GSM)@SF.netiSnakeGameServerManager(iSnakeGSM)hostedathttp://isnake.sf.netisusedto

managealltheinformationaboutiSnakegameserversbeinghostedovertheInternet.

TheiSnakeGSMhasbeendevelopedusingPHP.JavaWebStarttechnologyhasbeen

usedtodeployiSnakeapplicationatourwebsitewhichautomaticallydownloads/installs

iSnakeapplicationanditslibrarydependencies.Thisprovidesthegamerswiththefacility

ofoneclicklaunchoftheiSnakeapplication.Italsomakethedistributionofupdatesof

theiSnakeapplicationtotheendusersveryconvenient.

TheiSnakeapplicationdeployedatourwebsitehasbeendigitallysignedbythe

iSnaketeamtoaddressthesecurityissuesrelatedtolaunchofInternetapplications.

13

Illustration 7: Block diagram of iSnake Game Server Manager at http://isnake.sf.net

6 ProjectManagement

The first thing we did before starting the work on iSnake was to register a project at

Sourceforge4.Apartfromhostingservices,itprovidedusseveralcodeandprojectmanagement

services.

Illustration8showsthesvncommitstatisticsfortheisnakecoderepositoryatsourceforge.We

collaboratedonprojectdocuments(includingprototypedesigns,projectplan,TODOlist,etc)

usingWIKI(http://isnake.wiki.sourceforge.net).

JUnittestsweredevelopedtoindependentlytestsomeofthemodulesbeforeintegration.The

integrationofmodulesdevelopedbythethreedeveloperswasperformedinthreephases:

Phase 1 Integration (Sep. 28, 2007) chat functionality of the game was tested

successfully

4 http://www.sourceforge.net

14

Illustration 8: Commit statistics for iSnake subversion repository at http://isnake.svn.sourceforge.net

Phase2Integration(Oct.06,2007)successfultestingofbasicversionofmultiplayer

snakegame

Phase3Integration(Feb1726,2008)integrationofallthemodulesforiSnake0.1

Betarelease.

7 Documentation

Documentationofeverytaskbeingdoneintheprojectwasapriorityforalltheteammembers.

Almost every portion of the source code contains full code documentation conforming to

Javadocstandards.

Thereexiststwopathfindingalgorithmsthatimplementsintelligentopponentinthegameviz

BlackmambaandViper.Thesetwoalgorithmshavebeenfullydocumentedwithillustrations5.

The protocol devised for communication between game server and clients has been

documentedinANNEXD.

8 Limitations

ThelimitationsofpresentimplementationofiSnakeare:

ThepresentimplementationofiSnakecanonlybeplayedinLAN.Duetolargelatency

timeandbandwidthlimitation,itcannotbeplayedovertheInternet.

Pathfindingalgorithms(BlackmambaandViper)implementedinthisgamehavetheir

owncomputationlimitationswhichhasbeendescribeinANNEXA,B.

5 Refer to ANNEX A,B

Illustration 9: Screen shot of a snippet of source code showing method comments conforming to javadoc standards.

Fullstresstestoftheapplicationhasnotbeendoneyet.Hence,theresponseofgame

serverinunpredictablesituationscannotbehandledproperly.

iSnake'sGameServerManager(iSnakeGSM)locatedathttp://isnake.sf.netisstillin

itsearlydevelopmentphase.Therearesomeunresolvedsecurityissues.

9 FutureEnhancements

PortiSnaketocellphoneplatformandOneLaptopPerChildOLPC(whichusesSugar

Desktopenvironment).Thepresenceofseveralconnectivityoptions(Bluetooth,WIFI,

GPRS,CDMA)incellphonesmakesitaveryattractiveplatformforamultiplayergame

likeiSnake.LocalWIFInetworkformedbykidsusingOLPClaptopscanbeusedasa

platformforiSnake'sdeployment.

AsiSnakegameservercommunicateswithremoteplayingusingawelldefinedand

very simple protocol (Refer to ANNEX D), iSnake clients programmed in other

programmingplatformlikeFlash,Python,etccanbedeveloped.

10 Conclusion

Weweresuccessfulincreatingamultiplayerversionoftraditionalsnakegame.Thecomputer

controlledintelligentopponentshavebeensuccessfullytestedinthegameisauniquefeature

ofiSnake.

Welearnedseveral project management techniquesusedbyprofessionals todevelop large

scale project. The experience of working in team and integration of modules developed

independently,withjustrequirementspecifications,isaveryimportantachievementforthe

iSnaketeam.

11 References

Books

1. TheJavaProgrammingLanguage,byKenArnold,JamesGosling,DavidHolmes

ADDISONWESLEY,2000,ISBN8178081482

2. JavaThreads,SecondEdition,byScottOaks,HenryWong

O'REILLY,1997,ISBN8173660573

3. CoreJavaVolumeI/II,SeventhEdition,byCayS.Horstmann,GaryCornell

PEARSONEDUCATION,2005,ISBN8129709325

4. Introduction to Algorithms, Second Edition, by Thomas H. Cormen, Charles E.

Leiserson,RonaldL.Rivest,CliffordStein

MITPRESS,2001,ISBN8120321413

5. HeadFirstJava,SecondEdition,byKathySierra,BertBates

O'REILLY,May2003,ISBN8173666024

Websites

1. NetbeansCommunityDocs

http://wiki.netbeans.org/wiki/view/CommunityDocs

2. TheInkscapeTutorialsBlog

http://inkscapetutorials.wordpress.com/

3. SmashingMagazineOnlinemagazinefordesigners

http://www.smashingmagazine.com/

4. TheJavaTutorials

http://java.sun.com/docs/books/tutorial/

5. TimingFramework

https://timingframework.dev.java.net/

6. JavaGaming.org'sForum

http://www.javagaming.org/forums/index.php

7. MITOpenCourseWare6.831UserInterfaceDesignandImplementation

http://ocw.mit.edu/OcwWeb/ElectricalEngineeringandComputerScience/6831Fall

2004/CourseHome/index.htm

8. Amit'sA*PageTutorialonA*Pathfindingalgorithms

http://theory.stanford.edu/~amitp/GameProgramming/

9. Arianneamultiplayeronlinegamesframework

http://arianne.sourceforge.net/

10.JavaDesktopCommunityBlog

http://community.java.net/javadesktop/

11.JavaForum

http://forum.java.sun.com

12.BlogofRomainGuycoauthorofFilthyRichClients

http://www.curiouscreature.org/

13.FilthyRichClientsExamples

http://www.filthyrichclients.com/

14.ADistributedMultiplayerGameServerSystem

http://warriors.eecs.umich.edu/games/papers/quakefinal.pdf

15.TheJavaDevelopersAlmanac1.4

http://www.exampledepot.com/

16.ApacheMINASampleprogramsandtutorials

http://mina.apache.org/

17.PHPDocumentationforXMLlibrary

http://www.php.net/

18.QuantumRandomBitGeneratorService(QRBG)

http://random.irb.hr/

ANNEXA:BlackmambapathfindingalgorithmProposedby:AbhishekDutta

1Somedefinitionsandnotations

1.1BoundingRectangle(br)Itisarectangleinwhichthesourceandthetargetlieattwooppositecornersofthe

rectangle.SourceBoundingRectangle(sbr0)andTargetBoundingRectangle(tbr0)

representtheboundingrectanglesfromsourceandtargetwhicharethesame

rectangle.

1.2PartialBoundingRectangle(pbr):Theserectangles toucheither thesourceor thetarget nodeandnotboth. Two

partial boundingrectangles touching 'S' and 'T' formpaths fromsource to the

targetnode.

SourcePartialBoundingRectangle(spbr)

Thepbrtouchingthesourcenode'S'.

TargetPartialBoundingRectangle(tpbr)

Thepbrtouchingthetargetnode'T'.

RefertoIllustration10

1.3Notations:

1.3.1brNM

denotesaboundingrectanglethatspans(ortouches)Nnodesalongthexaxis

andMnodesalongtheyaxis.

ANNEXA A1

1.3.2spbrNM

denotesasourcepartialboundingrectanglethatspans(ortouches)Nnodes

alongthexaxisandMnodesalongtheyaxis.

1.3.3tpbrNM

denotesatargetpartialboundingrectanglethatspans(ortouches)Nnodes

alongthexaxisandMnodesalongtheyaxis.

1.3.4hpNM

denotesahoppingpoint(coordinatespecifiedwithreferencetosource)along

whichspbrNMandtpbrNMareformed.This coordinatepoint iscommonto

bothspbrNMandtpbrNM

1.3.5NumberingofPaths

Foranygivenboundingrectangle(br)thereareonlytwopossiblepathsasshow

inIllustration11.Pathnumberingconventionappliedis:

Path1: The xcoordinate of the path first changes followedby change in y

coordinate

Path2: The ycoordinate of the path first changes followedby change in x

coordinate

Asource(S)andtarget(T)canbeplacedinfourpossiblewayssuchthatthey

lieonoppositeendsofthediagonal.Consideringthefourposition(A,B,C,D)as

depictedinIllustration11,wehavethefollowingfourcases:

1.3.5.1'S'placedatpositionAand'T'placedatpositionC

Path1=ABC,Path2=ADC

1.3.5.2'S'placedatpositionBand'T'placedatpositionD

Path1=BAD,Path2=BCD

1.3.5.3'S'placedatpositionCand'T'placedatpositionA

Path1=CDA,Path2=CBA

ANNEXA A2

1.3.5.4'S'placedatpositionDand'T'placedatpositionB

Path1=DCB,Path2=DAB

2Basisofthisalgorithm

Inabsenceofanyobstacles, thecostofmovingfromonenodetoanother is constant

throughoutthegamefield.Hence,theshortestpathisalongtheboundingrectangleedges

ifnoobstaclesarepresentinthepathasshowninIllustration11.

Bothpath1andpath2haveequaltravelingcost providedthatnoobstaclesarepresent

alongthosepaths.Foranygivenbr,ifthereexistsapathfromsourcetotargetinsidethe

brthenitwillbetheshortestpath.

3Pathsgeneratedbypartialboundingrectangles

Fourpathsaregeneratedbythesourceandtarget partial boundingrectanglesforthe

givenhoppingpointasshowninIllustration12.

ANNEXA A3

Illustration 10: Bounding rectangle (br - dotted gray), Source bounding rectangle (spbr - dotted red) and Target bounding rectangle (tpbr - dotted green)

Illustration 11: Two possible paths along the edges of the bounding rectangle (dotted red line rectangle) provided no obstacles exists along the path

Foranygiven(S,T)pair,wemovethehoppingpointalongthediagonaljoiningSandT.

Specialconsiderationsisrequiredwhen:

obstacles(wall)arepresentalongthepathsformedusingtheboundingandpartial

boundingrectangles.

Nopossiblepathcanbefoundusingallthepossiblecombinationsofthepartial

boundingrectangles.

theboundingrectangleisnotasquare(ie:forbrNM,NM)

4Descriptionofthealgorithm

Instead of considering all the possible cases at once, let us consider the working of

algorithminseveralstages(withincreasingcomplications).

4.1[A]SymmetricBoundingRectangles(SimpleCase)Forillustrationpurpose,letusfirstconsideragamefieldof6x6nodeswheresource

andtargetareplacedat'S'and'T'respectivelyasshowninFigureA1.Thefollowing

seriesofstepsareexecutedtofindapathfromsourcetotarget.Ifobstacleisfoundin

ANNEXA A4

Illustration 12: Four possible paths generated by source and target partial bounding rectangles (spbr,tpbr - depicted using red and green dotted lines respectively) for a given hopping point

all possiblepathofanstagethenextstageischecked.Theseriesofstepstakento

obtainapathfrom'S'to'T'are:

4.1.1Procedureoffindingpathforagiven(S,T)pair

4.1.1.1FigureA2initiallythehoppingpointishp66(onthetarget).twopaths

formedalongtheboundingrectanglebr66(showninreddottedrectangle in

FigureA2)arecheckedforpresenceofobstacles.Ifnoobstaclesarefound,either

path1orpath2arechosen(refertoIllustration11).Asbothpath1andpath2

havesamepathlength,choicebetweenthesetwopathsismadebasedonsome

combinationofsubpathsandchoosingthepathwhoselengthisshortest.

4.1.1.2FigureA3fourpaths(refertoIllustration12)formedalongthesourceand

targetpartialboundingrectangle(spbr55,tpbr22)arecheckedforpresenceof

obstacle.


targetpartialboundingrectangle(tpsbr44,ptbr33)arecheckedforpresenceof

obstacle.



obstacle.



obstacle.

4.1.1.6FigureA7Thisstepisnotnecessarytoexecuteasthetaskhasalready

beenperformedinStep1usingtheboundingrectangle(br66).

SeeIllustration13forillustrationofsteps1to6

Computationoverheadcalculations

Letthetimerequiredtocheckwhetherapartialboundingrectanglehasanobstacle

ANNEXA A5

=T1

timerequiredtocheckwhetheraboundingrectanglehasanobstacle=T2

foragamefieldNxN(rowxcol)

alsolet(tocreatetheworstcase)

thesource'S'belocatedat(1,1)

thetarget'T'belocatedat (N,N)

Totalno.ofpossiblehoppingpoints(excludingthesource)=N1

Hence,total time required to calculate a path6 = T2 + N * T1

6 See section Requirements of this algorithm

ANNEXA A6

ANNEXA A7

Illustration 13: Illustrations for [A] Symmetric Bounding Rectangles (Simple Case)

4.1.2Backtracking

If4.1.1.1to4.1.1.6doesnotgiveapathfrom'S'to'T'thetechniqueofbacktracking

willbeapplied.Toillustratetheprocessofbacktrackingletusconsiderthescenario

showninIllustration14.

Thepathsgeneratedfromtheboundingrectangle(br44)andallthepossiblepartial

boundingrectanglescontainobstacle.Hencetheprocessdiscussedabovewillnot

resultinanypathfrom'S0'to 'T'.Forsuchscenariowecanapplytheprocessof

backtracking.

ANNEXA A8

Illustration 14: Game field scenario when all the paths formed by bounding and partial bounding rectangles contain obstacle.

Backtrackinginvolvesmovingtothenextouter(asinnerboundingrectanglesdonot

contain any path for sure) bounding rectangle a path to the target is found.

Illustration15showstheresultofbacktracking.BacktrackingfromS0toS1(the

nextouterboundingrectangle)resultsinaboundingrectanglebr55.Thisbounding

rectangledoesnotalsoresultinanypathfromS1toT.Hence,nextouterbounding

rectangleischecked.

The next outer bounding rectangle (br66) is formed at node S1 as shown in

ANNEXA A9

Illustration 15: Next outer bounding rectangle (br55) is checked for a path from node S1 to T.

Illustration 16: Next outer bounding rectangle (br66) is checked for a path from node S2 to T.

Illustration16.ThisboundingrectanglehasapathfromS2toT.Hence,thepossible

pathiscalculatedtoreachfromS2toT.

AswenowhaveapathfromS2toT,weneedtocalculateapathfromS0toS2so

thatwecanultimatelyreachTfromS0.NowwecalculatethepossiblepathfromS0

toS2usingthestepsdiscussedaboveasshowninIllustration17.

Byjoiningthepathsformedfromtheabovetwostepscanbecombinedtoforma

pathfromS0toT.

4.1.2.1Determiningnextouterboundingrectangleduringbacktracking

Although the vertex for next outer bounding rectangle (required for

backtracking)canbethenextcoordinateontheextendeddiagonal(asshownin

Illustration 15,16), a simple technique can greatly reduce the number of

backtrackingstepsofbothsourceandtarget.

Letsource(S)andtarget(T)beplacedasshowninIllustration18.Apathfrom

S to T contains twoedges. Path1 contains edge1andedge2. Path2contains

edge4 and edge3. While determining whether a path contains obstacle, the

algorithmmustalsodeterminewhichedgescontainsobstacles(ifany).

ANNEXA A10

Illustration 17: Path from node S0 to S2 is calculated using the process discussed before (after a path is found from S2 to T

Wecanapplythefollowingalgorithmtodeterminetheouterrectanglesrequired

duringbacktrackingforsource.

if(edge1containsobstacle) {


sourceouterrectanglevertex=S'

}else {

sourceouterrectanglevertex=S'''

}

}else {


sourceouterrectanglevertex=S''

}else {

nobacktrackingrequired

}

}

Theouterrectanglefortarget,duringbacktracking,canbedeterminedbyapplying

similarlogicforedge2andedge3.

Thistechniqueworksfordifferentorientationofsourceandtargetasdescribedin

Section1.3.5NumberingofPaths

ANNEXA A11

Illustration 18: Four edges (1-4) formed out of a bounding rectangle and the possible backtracking vertices for S and T

4.1.2.2Mergingthepathsformedwhilebacktracking

Whilebacktrackingseveralsubpathsarecreatedwhilerequirestobemergedto

formthefinalpathfromsourcetotarget.Letusconsideracaseasdepictedin

Illustration19.

Duetothepresenceofwall(greenblocks),SandThastobacktracktoS'andT'

positionsrespectively.Hereweobtainthreesubpathswhichare:

Path from S to S' : depicted by red colored line from S to S' (SubPath1)

PathfromS'toT:depictedbybluecoloredlinefromTtoT'(SubPath2)

PathfromT'toT:depictedbypinkcoloredlinefromT'toT(SubPath3)

We need to combine these three paths to obtain a final path from S to T

(depictedbythickblackline).Ifweaddthesethreepathsdirectly,thefinalpath

willcontainoverlappingpaths(whichisnotrequired).Thefollowingalgorithm

canbeappliedtocomputethefinalpath(thatdoesnotcontainanyoverlapping

regions).

START

Step1:InitializeFinalPathwiththecontentsofSubPath1

ANNEXA A12

Illustration 19: Sub paths formed during backtracking. Final path from S to T obtained by combining the sub paths.

FinalPath=SubPath1

Step 2: Now perform the following operations for each cell coordinate

presentinSubPath2andSubPath2(K=2,3)

cellCoordinate=SubPathK.getCellCoordinate()

if(FinalPathcontainscellCoordinate) {

removecellCoordinatefromFinalPath

}else {

addcellCoordinatetoFinalPath

}

Step3:FinalPathcontainsdiscontinuitiesatthebendsofpath.Searchfor

consecutivecellcoordinateforwhichbothxandyvaluesofthecoordinate

change(ie:|dx|=1,|dy|=1).

Step4:Correctthesediscontinuitiesbyaddingthemissingcellcoordinates.

END

4.2[B]AsymmetricBoundingRectangles

4.2.1SimpleCase

A problem arises when the bounding rectangle is asymmetric as shown in

Illustration20.

Thesolutiontothisproblemistoinsertrequirednumberofdummynodesbetween

'S' and 'T' so that the newbounding rectangle becomes symmetric as shown in

ANNEXA A13

Illustration 20: Case of asymmetric bounding rectangle (br63)

Illustration 21. The algorithm applied in [A] Symmetric Bounding Rectangles

(SimpleCase)canbenowappliedbyconsideringthedummynodesasnormal

gamefieldnodesfreefromanyobstacles.

4.2.2SandTlyingonsamestraightline(verticalorhorizontal)

Thiscaseariseswhenboth 'S' and 'T' lieonsamestraightline(horizontalor

vertical)asshowninIllustration22.

The case can be converted to [A] Symmetric Bounding Rectangle (Simple

Case)casebyaddingdummynodesasshowninIllustration23.

ANNEXA A14

Illustration 21: The bounding rectangle (br66) is made symmetric by adding required no. of dummy nodes

Illustration 22: Another case of asymmetric bounding rectangle (br61)

5Requirements

5.1ConstanttimealgorithmforobstacledetectionTheremustexistaconstanttimealgorithmthatcananswerthequestionDoesthe

given bounding or partial bounding rectangle contain any obstacle?. The

constant time algorithm requirement means that the YES/NO decision of this

algorithmshouldnotdependonthesizeofrectangleunderconsiderationorthe

numberofobstaclespresentinthegamefield.

AnimportantobservationforiSnakegameisthattheobstaclesinthegamearenot

dynamic.Inotherwords,theobstaclesremainconstantuntilagivenFOODiseaten

byoneoftheplayers.Hencewecanassumethattheobstacleisconstantduringthe

executionofthispathfindingalgorithm.

Weapply the followingalgorithmtodetect whether agivenboundingrectangle

containsanyobstacles.

START

ANNEXA A15

Illustration 23: The case can be converted to [A] Symmetric Bounding Rectangle (Simple Case) case by adding dummy nodes

Step1:Let(x1,y1)=onecorneroftheboundingrectangle

(x2,y2)=diagonallyoppositecorneroftheboundingrectangle

obstacle=asetcoordinatesdefiningtheobstacle(wall)

Step2:Repeatstep2foreachcellcoordinateinobstacle

oc=obstacle.getCellCoordinate()

path1HasObstacle=true,path2HasObstacle=true

if(x>=x1andx=y1andy

if(path2HasObstacle)

returnPATH1 is OBSTACLE FREE

else

returnPATH1andPATH2are OBSTACLE FREE

}

END

6Limitations

6.1Thisalgorithmdoesnotconsiderthetransparentgamefieldboundary(entrytoone

sideofthefieldcausesexitintheoppositesideofthefieldasdepictedinIllustration

24)duringpathcalculation.Duetothislimitationthecomputedpathisnotoptimal.

6.2Thehoppingpointsarealwaystakenfromthediagonallinejoiningthesourceand

target.Becauseofpropertyofthealgorithm,itisnotabletocomputepathswhena

complexstructureofwall,asshowninIllustration25,ispresent.Thisisthereasonwhy

Blackmambaimplementationentersinfiniterecursionforsuchobstacles.

ANNEXA A17

Illustration 24: Transparent boundary of the game field

ANNEXA A18

Illustration 25: Only 1 hopping point prevents this algorithm from computing path in presence of a complex structured wall

ANNEXB:ViperpathfindingalgorithmProposedby:SurajSapkota

1 Assumptions

Thisalgorithmassumesgamefieldasfollows:

The rectangle with the dotted boarder is the viewport(vp) of each player. Other

rectangles attached with it in each side are the virtual view port(vvp) in their

correspondingsides.

Smallyellowboxisawallunit.Groupofattachedwallunitissaidtobewall.

Theborderofthegamefieldaretransparentunlessthereiswall.

Wallistheonlythingthatasnakecanstriketo.

Therecanbemultiplewallinthesamegamefield.

ANNEXB B1

Illustration 1: The game field (unfolded Envelop)

Finallyconsideringall these, theaimof this algorithmis tofindall (theremaybe

multiplepathofsamedistance)shortestpathfromthesnake(head)tofood.However

asaresultitwillreturnonlyoneamongthosepaths.

2 Principalandimplementationofthisalgorithm.

Thisalgorithmwillnotdealwithfindingonlyoneshortestpathinsteaditcalculatesmultiple

pathbetweenthesourceandthedestination,andallofthesepathhavethesamedistance,the

shortestdistance.Actually theresultisnotintheformofmultiplepath,merelyitisa

collectionofthepointsthatitmustpassthrough.Itisthepositionofthepointsthatmake

thepathmultiple.Itisdescribedlaterinmoredetail.

Thealgorithmfollowsfollowingsteps:

1.Thisalgorithmbeginswithsplittingallthegamefieldintosmallrectangles(Fundamental

openrectangle7(FOR8)),sayR1,R2,R3,...Rn.Ifgamefield(onlyviewport),asawholeis

saidtobeG.Thenmathematicallythewall,Wcanbedefinedas:

W=GR1UR2UR3U...URn

Broadly,thisalgorithmdealswithsplittingthegamefieldintoseveral(asmany)rectangles

suchthat,theunionofallthesesmallrectanglesresultinthegamefieldthatexcludewall.ie,

thesnakecanmovesafelyfromanypointintherectangle(Ri)toanyotherpointwithinthe

samerectangle(Ri)andhencecalledOpenrectangles(OR).

7 Open rectangle is a rectangle that does not contain any wall. Within it snake can move freely.8 The algorithm of generating FOR is discussed later.

ANNEXB B2

2.NextwedefineGate9(GateasinreallifeisawaytomovefromaFORtoanotheradjacent

FOR) calculatetheshortestdistancebetweeneachtwoGatesofeach FOR(eg:theshortest

distancebetweentherectanglesR1andR5aredeterminedbythedistancebetweenthetwo

gatesofR3sharedwithR1andR5respectively).

3.Afterthecalculationoftheshortestpath,agraphasshowninIllustration4isformed.

Intheabovegraph

i. Thedottedlinesdefinesdirectconnection,thedirectpath.

ii. Thedarklineshowsa1stepindirectconnectionbetweenthoserectanglesthatarenot

connecteddirectly.

9 A gate must be common to only two FOR.

ANNEXB B3

Illustration 4: Graph

Illustration 3: "Illustration 2" in broader view

Illustration 2: Slitted into 6 small pieces of rectangle.

iii. Sij,besidewiththevertex,(ingraph)denotesthatFORiisconnectedtoFORjthrough

thisvertexandviceversa.Thiscanalsobecalledindirectpath.Anditpossesthepath

distance.

iv. There may be multiple indirect path. Eg: We can move form2 to 5 (S25) in two

differentways:via3or5.

Somedatathatareassociatedwiththerectangle(nodeinthegraph)isshownbelow.

4.Finallyafterallthesecalculation,wecancalculatethepathbetweentwoFOR's,thesource

andthedestinationwithshortestdistance.Whentwopoints(sourceandtarget)aregivenwe

candeterminetheFOR's,theylieinandcancomputethepathbetweenthem.

ANNEXB B4

Illustration 5: Data associated with each node

Illustration 7: Zoomed view of "Illustration 6"Illustration 6: Path for a sample case.

The above sample case shown in illustration 6 and 7, shows the path calculated by the

algorithmfromthesnake(redonepointedbyanarrowA)tothefood(blueonepointedbyan

arrowF).ThepointspointedbythearrowsA,B,C,D,EandFarepoints(HopingPoints)that

theintelligentplayermustpassthrough.Andthusallowingmultiplepossibilityforpath.

Thepathismultiplebecause,thereexistmultiplewaytogofromAtoBandEtoF.Further

therectanglesasformedbythepointsAandB(EandF)canalsobecalledDerivedopen

rectangle(asitdoesn'tcontainanywall,andhenceallowsfreemovementofthesnakeinside

it).

3 FordividingtheGamefieldintofundamentalopenrectangle:

Thealgorithminvolvesslicingthegamefieldincyclicorder

inanticlockwisedirectionstartingwiththeleftedge.Asthe

gamefieldinitiallyhasnoterminatingedge(asenvelope)we

startwith(visually)leftedgeofthegamefield.

1. InitiallystartingfromtheZerothcoordinatemoveto

bothsidesuntilitstriketowall(unit).NameitFundamentalOpenRectangle(FOR1and

FOR2orJustR1andR2).Illustration8and9.

2. Now the gamefield has shrinked to as shown in

Illustration10. (It nowhas changed to cylindrical

shapefromenvelopeshape.)

3. Moving in anticlockwise direction, Slice from

bottom in both direction (up and down) to get other two rectangle R3 and R4.

Illustration11.

ANNEXB B5

Illustration 8: Step 1 (a)

Illustration 9: Step 1 (b)

Tillthissteptherectanglewasnotbounded(either in

allfoursides(envelop)orintwosides(topandbottom)

(cylinder)).Fromthissteponwardthe sliced game

fieldwouldbebounded.

4. Now try to slice rectangle from top left, bottom

left,bottomrightandtoprightrespectively.Herewefail

toslicetherectanglefromtopleftandbottomrightas

thereiswall(unit)attheedge.

Wecannowcreatetwonewrectanglesfrombottomleft

andtoprightnamelyR5andR6.Illustration13.

5. Nowsliceawaytheboundarylayerofthegamefield

formedinIllustration13.ShowninIllustration14.

6. Asearlieragaintrytoslicethegamefieldintheanticlockwisedirectionstartingfrom

left.ItwillresultintwomorerectangleR7andR8.Illustration15.

Duringthis weassumealreadyslicedrectangle as a

hollowspace.

7. ForFurtherOptimizationweproceedbybreakingdowntherectanglethattouches

itself(eg:inthiscase,thetopedgedofrectangleR1touchitselftoitsbottomedge).These

typeofrectanglesaredividedinthemiddle.Thisresultsinbestutilizationofthetransparency

oftheGameField.

ANNEXB B6

Illustration 10: Step-2

Illustration 12 Illustration 13: Step 3

Illustration 14: Step 4Illustration 15

Illustration 11: Step-3

4 SpecialcaseforGameFieldwithnowall

Ifthereisnowallwesimplychopthegamefieldverticallyandhorizontallyfromthemiddle

resultingin4FOR's.Thisresultsinmaximumutilizationofthetransparencyofthegame

field.TheresultisshowninIllustration17.

ANNEXB B7

Illustration 16: The Final Result

Illustration 17: Sliced Game Field with no wall

5 SalientFeatures:

As most of the processing is done before the actual game starts, it must reduce the the processing time during the game-time.

The concept of open-rectangle allows multiple path, and hence within it the snake can be moved randomly towards the specified point. And hence it is intelligent.

Furthermore, during the calculation of the path the snake can move within the FOR in which it currently lie.

6 Limitations:

If the number of FOR increases to too high, then it will obviously be tough and slow to determine the shortest path.

ANNEXB B8

ANNEXC:Programflow

NOTE:"EXT"referstotheactionsthataretriggeredbyClientNetworkInterfacemodulewhen

messagesarereceivedfromgameserver

ANNEXC C1

Illustration 26: iSnake game application enters in STAGE-1 and exits through STAGE-5

Illustration 27: iSnake game application starts in STAGE-1 and this stage involves connection to game server specified by the player



ANNEXC C2

Illustration 28: In STAGE-2 players can chat with each other. The game will start only when all the players connected to the game server send READY signal



ANNEXC C3

Illustration 29: STAGE-3 involves receiving different game data (like wall coordinates, food coordinate, snakes start position, etc)



ANNEXC C4

Illustration 30: STAGE-4 involves synchronization with the game server



ANNEXC C5

Illustration 31: STAGE-5 represents the state when game is being played

ANNEXD:InterSnakeCommunicationProtocol

ThecommunicationbetweenthegameserverandclientapplicationsisdoneusingtheInter

SnakeCommunicationProtocol(ISCP).Theprotocolcontainsfivedifferentclasses.Theseare

listedbelow:

Information Usedfortransmissionofplayer'sinformation(name,color,

location). Used only when the player creates/joins the

game.

ChatMessage Transmitsthechatmessage.Worksonlybeforetheactual

gamestarts.

ControlSignal Transmitscontrolsignalsbetweenserverandclients.These

signalsaremainlyusedforsynchronization.

LevelData Sendsdatarequiredonlevelchange(food,wall,score,life,

etc).Sentinitiallywhentheactualgamebeginsandthen

aftereverylevelchange.

Move Transmits the movement of clients, collision information

andalsotheinformationaboutfoodcapture.

Thecommunicationpacketsareencodedinbyteformatforthepurposeoftransmissionand

aredecodedinsimilarfashion.Theencodinganddecodingofpacketsinclientsideishandled

by ClientEncoder and ClientDecoder respectively. Similar for game server, encoding and

decodingishandledbyServerEncoderandServerDecoderrespectively.

For instance, the server encoder for chat message is known as ChatServerEncoder. The

encodersanddecodersareplacedundernet.sf.isnake.codec.

Onthebasisofcommunicationpacketflow,wecanclassifythecommunicationbasicallyinto

twotypes:

Client Initiated Communication: In this type of communication, the client first

ANNEXD D1

encodesthepacketwithnecessarydata.Sendittoserverinflippedorder.Flippingis

requiredsothatitgetsreceivedincorrectorderattheotherend.Theserverdecodesit.

Theserverreencodes thedatawithsomefurther informations(if requiredsuchas

sender'sId)andflipsit.Thispacketisretransmittedtoclientswhereitisdecoded.The

communicationcycleisshownbelow:

ServerInitiatedCommunication:Inthistypeofcommunication,serverfirstencodes

thepacketwithnecessarydataandtransmitsinflippedorder.Thepacketisdecodedon

clientside.Thecommunicationcycleisshownbelow:

Thefiveclassesofcommunicationcansendvariousmessages.Allthemessagesaredecoded

thesamewaytheyareencoded. Followingconventionsareusedindepictingtheencoding

overhere:

Symbol Meaning

Showsfieldstobesentalongwithidentifier

() Showsthedatatypeofthefield.However,allthefieldsareconvertedintobytewhileencodingandondecodingtheyarereceivedasbytesandconvertedtoproperdatatype.

id Representstheplayerid(anintegerusedtouniquelyidentifyaplayerinthegame).

[] Thefieldswithin[]arepartofanarrayintheprotocolclass.

Class: Chat Message1 Packet ChatText

Identifier CH

Type ClientInitiated

Description Isusedtotransmitachatmessagetypedbyaclienttootherclients.

to_idisrequiredforonetoonecommunicationwhichisnotcurrently

ANNEXD D2

Client Encoder Client Decoder Server Encoder Server Decoder

Client Decoder Server Encoder

allowedinthegamebuthasbeendesignedforfutureenhancements.0

isbeingsentasto_idwhichisbasicallyamulticastid.

ClientEncoder CH

ServerEncoder CH

Class: Information1 Packet Playerinfo

Identifier IN


Description Isusedtotransporttheinformationsofaplayerviz;name,colorand

location.

ClientEncoder IN

ServerEncoder IN

Class: ControlSignal1 Packet Acknowledgment

Identifier AK


Description ThispacketissentwhenaclientsuccessfullyreceivesLeveldata.The

status_code field has beenreserved for future enhancements. As of

nowitissentas0.

ClientEncoder AK

ServerEncoder AK

2 Packet Quit

Identifier QT

ANNEXD D3


Description Sentwhenaclientquitsthegame.

ClientEncoder QT

ServerEncoder QT

3 Packet Ready

Identifier RY


Description Issentwhentheuserspecifieshisreadinesstostartthegame.

ClientEncoder RY

ServerEncoder RY

4 Packet ID

Identifier ID

Type ServerInitiated

Description Thispacketissentbyservertoclienttoassignanidtotheplayer.This

isdoneassoonastheclientsendshisinformation.

ServerEncoder ID

5 Packet Start

Identifier ST


Description Represents start of various events in the game on the basis of

status_code.status_code0representsthe beginning of

transmissionof leveldata.status_code1representsthebeginningof

ANNEXD D4

levelsynchronizationtaskbeforebeginningofalevelandstatus_code2

isasignaltostarttheactuallevelplay.

ServerEncoder ST

6 Packet Stop

Identifier SP


Description Representstheendoflevel.

ServerEncoder SP

7 Packet Force

Identifier FR


Description Thiscommunicationpacketforcesaplayertosendareadypacketwhen

allothershaveexpressedtheirwillingnesstobeginthegame.

ServerEncoder FR

8 Packet NoAcknowledgment

Identifier NK


Description Thispacketissentbyserverwhentheinformationsuppliedbyclientis

not valid. status_code here represents field which has invalid data.

Invaliddataoccurswheninformationfieldcontainsreservedcharacters

orduplicateentry.

ServerEncoder NK

ANNEXD D5

Class: LevelData1 Packet Beginfrom

Identifier BF


Description The packet sends starting coordinate of all the players in a single

packet.Theplayer beginslevelfromthiscoordinateandisresettothis

coordinateoncollision.

ServerEncoder BF[]

2 Packet Score

Identifier SC


Description Sendsscoreofalltheplayersinthepacketonbeginningofalevel.

ServerEncoder SC[]

3 Packet Level

Identifier LV


Description Sendsthelevelnumbertotheclients.

ServerEncoder LV

4 Packet Life

Identifier LF


ANNEXD D6

Description Sendsthelifecountforeachplayeronbeginningofalevel.

ServerEncoder LF[]

5 Packet Wall

Identifier WL


Description Sendsthewallcoordinatestotheclients.

ServerEncoder WL[]

6 Packet Food

Identifier FD


Description Sendsthefoodcoordinatestotheclientsonthebeginningofalevel.

ServerEncoder FD[]

Class: Move1 Packet Collide

Identifier CL


Description Thepacketissentwhenaplayerloosesalife.Possibilityofmorethan

oneplayers collidingonsameturnhasbeentakenintoaccount. At

present,however,wearecheckingthe collision on server and the

communicationisthusServerInitiated.

ANNEXD D7

ClientEncoder CL

ServerEncoder CL[]

2 Packet Move

Identifier MV


Description Carriesthechangeinxandy(dxdy)oftheclientstotheserver.Server

mergeschangeincoordinateofalltheclientsinanewMVpacketand

transmitstotheclients.

ClientEncoder MV[]

ServerEncoder MV[]

3 Packet Eaten

Identifier ET


Description Serversendsthepacketwheneverthefoodgetseaten.Thispacketalso

initiatesthe generationofFoodpacketasalevelcanhavemorethan

onefood.

ClientEncoder ET

ServerEncoder ET

FD[]

ANNEXD D8

1 Acknowledgment 2 Abstract 3 Objectives 4 Programming Environment 5 Methodology 5.1 iSnake Client Application 5.1.1 Client Encoder/Decoder 5.1.2 Client Network Interface 5.1.3 Input Handler 5.1.4 Game Field Matrix 5.1.5 Game Field Canvas 5.1.6 User Interface Components 5.1.7 Game Controller

5.2 iSnake Game Server 5.2.1 Server Encoder/Decoder 5.2.2 Server Network Interface 5.2.3 Virtual Game Field 5.2.4 Player Information Manager 5.2.5 Random Number Pool 5.2.6 Status Server 5.2.7 Server Core

5.3 Intelligent Autonomous Opponent Snakes 5.4 iSnake Game Server Manager (GSM) @ SF.net

6 Project Management 7 Documentation 8 Limitations 9 Future Enhancements 10 Conclusion 11 References 1 Some definitions and notations 1.1 Bounding Rectangle (br) 1.2 Partial Bounding Rectangle (pbr): 1.3 Notations: 1.3.1 brNM 1.3.2 spbrNM 1.3.3 tpbrNM 1.3.4 hpNM 1.3.5 Numbering of Paths

2 Basis of this algorithm 3 Paths generated by partial bounding rectangles 4 Description of the algorithm 4.1 [A] Symmetric Bounding Rectangles (Simple Case) 4.1.1 Procedure of finding path for a given (S,T) pair 4.1.2 Backtracking

4.2 [B] Asymmetric Bounding Rectangles 4.2.1 Simple Case 4.2.2 S and T lying on same straight line (vertical or horizontal)

5 Requirements 5.1 Constant time algorithm for obstacle detection

6 Limitations 1 Assumptions 2 Principal and implementation of this algorithm. 3 For dividing the Game field into fundamental open rectangle: 4 Special case for Game Field with no wall 5 Salient Features: 6 Limitations:

Documents

isnake_kucc2008_report.pdf