人工智能课件第四次课.ppt

人工智能课件第四次课.ppt

《人工智能课件第四次课.ppt》由会员分享，可在线阅读，更多相关《人工智能课件第四次课.ppt（63页珍藏版）》请在冰豆网上搜索。

基本路径搜索和航点应用BasicPathfindingandWaypointsAtitsmostbasiclevel,pathfindingissimplytheprocessofmovingthepositionofagamecharacterfromitsinitiallocationtoadesireddestination.基本路径搜索是从初始位置移动到目标位置的过程。

基本路径搜索Basicpathfindingalgorithmif（positionXdestinationX）positionX-;elseif（positionXdestinationY）positionY-；elseif（positionYdestinationY）positionY+;限制条件SomelimitationsSimplepathmovementLine-of-sightpathmovement障碍问题Problemswithobstacles

（1）随机运动避开障碍RandomMovementObstacleAvoidanceRandommovementcanbeasimpleandeffectivemethodofobstacleavoidance.随机运动能够简单而有效地解决避开障碍。

Randommovementobstacleavoidancealgorithmifplayerinlineofsightfollowingstraightpathtoplayerelsemoveinrandomdirection

（2）围绕障碍物的追踪TracingAroundObstaclesThismethodcanbeeffectivewhenattemptingtofindapatharoundlargeobstacles,suchasamountainrangeinastrategyorrole-playinggame.解决围绕大障碍物寻找路径的问题。

基本追踪BasictracingComputer-controlledcharacterItsgoal存在的问题ProblemwithtracingDecidingwhentostoptracing?

什么时候停止追踪？

Weneedawaytodeterminewhenweshouldswitchfromthetracingstatebacktoasimplepathfindingstate.如何从追踪状态转换为路径搜索状态？

Onewayofaccomplishingthisistocalculatealinefromthepointthetracingstartstothedesireddestination.解决方法-计算从追踪开始点到目标点的直线距离。

改进的追踪Improvedtracing改进的追踪ImprovedtracingTracingtheoutskirtsoftheobstacleuntilthelineconnectingthestartingpointanddesireddestinationiscrossedensuresthatthepathdoesntloopbacktothestaringpoint.沿着障碍物外围追踪时，穿过障碍物连接开始点和目标点，防止追踪路径又回到起点。

视线追踪Tracingwithlineofsight视线追踪TracingwithlineofsightWefollowtheoutskirtsoftheobstacle,butateachstepwechecktoseeifthedestinationisinthecomputer-controlledcharacterslineofsight.每一步检测是否处在视线之内。

Ifso,weswitchfromatracingstatetoaline-of-sightpathfindingstate.处在视线之内，路径搜索从追踪状态转换为视线搜索状态。

（3）标记路径搜索BreadcrumbPathfindingBreadcrumbpathfindingcanmakecomputer-controlledcharactersseemveryintelligentbecausetheplayerisunknowinglycreatingthepathforthecomputer-controlledcharacter.带标记的路径搜索是玩家无意地留下轨迹。

Eachtimetheplayertakesastep,heunknowinglyleavesaninvisiblemarker,orbreadcrumb,onthegameworld.每次玩家走一步，它就留下一个不可见的标记。

BreadcrumbtrailAtrollrandomlymovesaboutthetile-basedenvironmentuntilitdetectsabreadcrumbonanadjacentlocation.ai_Entityclass#definekMaxTrailLength15classai_Entitypublic:

introw;intcol;inttype;intstate;inttrailRowkMaxTrailLength;inttrailColkMaxTrailLength;ai_Entity（）;ai_Entity（）;变量说明#definestatementsetsthemaximumnumberofplayerstepstotrack.设置kMaxTrailLength为玩家标记轨迹的最大步骤数。

trailRow,trailColarraysstoretherowandcolumncoordinatesoftheprevious15stepstakenbytheplayer.trailRow,trailCol保存由玩家标记的15步的横、纵坐标。

标记数组的初始化Trailarrayinitializationinti;for（i=0;ikMaxTrailLength;i+）trailRowi=-1;trailColi=-1;记录玩家的位置Recordingtheplayerpositionsvoidai_World:

KeyDown（intkey）inti;if（key=kUpKey）for（i=0;i0）entityListi.row-;DropBreadCrumb（）;if（key=kDownKey）for（i=0;ikMaxEntities;i+）if（entityListi.state=kPlayer）if（entityListi.row=kMaxRows-1）entityListi.row+;DropBreadCrumb（）;if（key=kLeftKey）for（i=0;i0）entityListi.col-;DropBreadCrumb（）;if（key=kRightKey）for（i=0;ikMaxEntities;i+）if（entityListi.state=kPlayer）if（entityListi.colkMaxCols-1）entityListi.col+;DropBreadCrumb（）;设置标记DroppingabreadCrumbvoidai_World:

DropBreadCrumb（void）inti;for（i=kMaxTrailLength-1;i-）entityList0.trailRowi=entityList0.trailRowi-1;entityList0.trailColi=entityList0.trailColi-1;entityList0.trailRow0=entityList0.row;entityList0.trailCol0=entityList0.Col;追踪标记FollowingthebreadcrumbsThegoalistodetermineifanyoftheeightpositionsadjacenttothecomputer-controlledtrollcontainabreadcrumb.是否在八个相邻方向之一中有标记。

Followingthebreadcrumbsfor（i=0;ikMaxEntities;i+）r=entityListi.row;c=entityListi.col;foundCrumb=-1;for（j=0;j=0）entityListi.row=entityList0.trailRowfoundCrumb;entityListi.col=entityList0.trailColfoundCrumb;elseentityListi.row=entityList0.row+Rnd（0,2）-1;entityListi.col=entityList0.col+Rnd（0,2）-1;if（entityListi.row0）entityListi.row=0;if（entityListi.col=kMaxRows）entityListi.row=kMaxRows-1;if（entityListi.col=kMaxCols）entityListi.col=kMaxCols-1;Followingtheshortestpath12,11,10,9,8,7,6,2（4）PathFollowingItisnecessarytomovecomputer-controlledcharactersinagameenvironmentinarealisticwayeventhoughtheymightnothaveanultimatedestination.没有目的地的移动Car-racinggame赛车navigatearoadwaywantthecarstostayontheroadPathFollowing2-road1-outofbounds地域分析TerrainanalysisWeneedtoanalyzethesurroundingterrainanddecideonthebestmove.分析周围的地域并决定选取最佳移动。

Weexaminealleightdirectionsandtheneliminatethosethatarenotpartoftheroad.对八个方向检测，消除不在路上的部分。

Theproblembecomesoneofdecidingwhichoftheremainingdirectionstotake.决定选取哪一个方向移动？

地域分析Terrainanalysisintr;intc;intterrainAnalysis9;r=entityListi.row;c=entityListi.col;terrainAnalysis1=terrainr-1c-1;terrainAnalysis2=terrainr-1c;terrai