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User interaction and gameplay: Scripting, AI, Physics, and Behaviors How are Players and NPCs controlled? – Player’s interface – Scripting, AI, Physics,

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Presentation on theme: "User interaction and gameplay: Scripting, AI, Physics, and Behaviors How are Players and NPCs controlled? – Player’s interface – Scripting, AI, Physics,"— Presentation transcript:

1 User interaction and gameplay: Scripting, AI, Physics, and Behaviors How are Players and NPCs controlled? – Player’s interface – Scripting, AI, Physics, Behaviors Determines gameplay

2 User Interface Manual (hardware) – Keyboard, mouse – Controller: analog mini-sticks, D-pad, analog buttons Visual (screen display) – Active: menus, actions – Passive: status, HUDS – Score, lives, power, map, etc. – Split-screen, Whole screen, Invisible

3 User Interface: Unreal Controllers are non-physical actors which can be attached to a pawn to control its actions. – PlayerControllers are used by human players to control pawns – AIControllers are used to implement the artificial intelligence for the pawns they control. AIScripts can be associated with pawns placed in levels to modify their AIControllers. – ScriptedControllers can be used to make a pawn follow a scripted sequence HUD – Uses 2D Canvas

4 User Interface: VRML/X3D Sensor Nodes: – Drag Sensors: TouchSensor, SphereSensor, PlaneSensor, etc. – Proximity Sensor – Visibility Sensor HUD Prototype – Moves 3D object along with viewpoint

5 Scripting Native support the major concepts of time, state, properties, and networking (replication) which traditional programming languages don't address. Safety – a pointerless environment with automatic garbage collection – a safe client-side execution "sandbox To enable rich, high level programming in terms of game objects and interactions rather than bits and pixels.

6 Scripting Slow – C++ : 50M base language instructions per second – UnrealScript: 2.5 million - a 20X performance hit. create animation-driven or time-driven code – Exploit latent functions (like FinishAnim and Sleep)

7 Scripting: Time Most engines use Ticks – smallest unit of time in which all actors in a level are updated. A tick typically takes between 1/100th to 1/10th of a second. – limited only by CPU power; the faster machine, the lower the tick duration is. Synchronous vs. Asynchronous Zero-time vs. Latent Event cascade

8 Scripting Examples: UnrealScript Actor (extends Object) is the parent class of all standalone game objects in Unreal. – The Actor class contains all of the functionality needed for an actor to move around, interact with other actors, affect the environment, and do other useful game- related things. Pawn (extends Actor) is the parent class of all creatures and players in Unreal which are capable of high-level AI and player controls.

9 Scripting Examples: UnrealScript function ModifyPlayer(Pawn Other) { local xPawn x; //x is a variable x = xPawn(Other); if (x != None) { x.MaxMultiJump = MultiJumpCount; x.MultiJumpBoost = MultiJumpBoost; x.Health = StartingHealth; x.HealthMax = MaximumHealth x.SuperHealthMax = SuperDuberMaximumHealth }

10 Scripting Functionality: World Awareness native final function Actor Trace(HitLocation, HitNormal, TraceEnd, TraceStart, bTraceActors, Extent, Material) – casts a ray (aka "traces") into the world and returns what it collides with first. Trace takes into account both this actor's collision properties and the collision properties of the objects Trace may hit. Use Trigger – If a human controlled pawn is within the proximity of this trigger and hits their USE key, it activates this trigger. VRML: Proximity, Collision, Gravity, Visibility nodes

11 Scripting Examples: Unreal Animation Blending Multiple animation channels/stages are used to blend into the animation track. native final function AnimBlendParams( int Stage, BlendAlpha, InTime, OutTime, BoneName) – Before playing animation on any channel, you need to call AnimBlendParams to set up that channel. Channels are blended in order starting at the base channel (channel 0) with higher channels blended on top. – animations played on higher channels will mask animations played on lower channels, depending on the BlendAlpha of the higher animation channel and which bones the higher channel affects.

12 Scripting Examples: VRML Character Control function mouseinput(val,t){ newrot.angle=calcangle(val.x,val.y); touchval=val; mlen=val.length(); if (mlen) body2.rotation=newrot; loco(mlen,t); }

13 Scripting Examples: VRML function keyinput(k,t){ if (k==106){ //jump stand.stopTime=walk.stopTime=run.stopTime= jump.startTime=t; mlen=0; } if (k==119){ //w - walk mlen=1.5; } if (k==114){ //r- run mlen=2.9; } if (k==104){ //h- halt mlen=0; }

14 Scripting Examples: VRML if (k==38){ //up - faster mlen+=.2; } if (k==40){ //down - slower mlen-=.2; } if (k==39){ //right - turn newrot.angle= newrot.angle -.39; //16th of turn body2.rotation=newrot; } if (k==37){ //left- turn newrot.angle= newrot.angle +.39; body2.rotation=newrot; }

15 Scripting Examples: VRML if (mlen<0) mlen=0; touchval.x= mlen * Math.sin(newrot.angle); touchval.y= mlen * Math.cos(-newrot.angle); //print('ang='+newrot.angle); //print('x='+touchval.x+',y='+touchval.y); //print('mlen='+mlen); loco(mlen,t); }

16 Scripting Examples: VRML function loco(mlen,t){ if (mlen<0.4){ //print('STOP'); stand.startTime=t; walk.stopTime=t; run.stopTime=t; }else if (mlen<2.9){ //print('WALK'); stand.stopTime=t; walk.startTime=t; run.stopTime=t; walk.cycleInterval = 4 - (1.0 * mlen); }else{ // print('RUN'); stand.stopTime=t; walk.stopTime=t; run.startTime=t; run.cycleInterval = (2.0/(mlen-1.9)); }

17 Scripting Examples: VRML function engine(val,time){ //advance position each frame if (lasttime){ if (touchval.length()>=0.4) //not stopped body.translation= body.translation.add(touchval.multiply((time- lasttime)*.5)); } lastval=t; }

18 Artificial Intelligence Strong AI: the ability to perform activities normally thought to require intelligence, learning, and adapting. Weak AI: specialized intelligent qualities. Deterministic- predictable – Path Planning Nondeterministic – uncertainty – NPC learning to adapt to fighting tactics

19 Artificial Intelligence Chasing and Evading & Pattern movement Flocking Pathfinding – A* algorithm Logic: Finite State Machines, Fuzzy Logic Probability – Bayesian Adaptive – Neural Networks – Genetic Algorithms

20 Artificial Intelligence: Unreal AI Scripting allows enemies (and friends) to be controlled easily via external files that can be easily changed without map rebuilding. Almost every important NPC (non player character) in Unreal II has a long and detailed script behind it controlling its behavious and actions under various conditions

21 Artificial Intelligence: Unreal :MarinePatrol ontrigger ChangeMarinePatrol gotolabel MarinePatrol2 gotoactor PathNode0 gotoactor PathNode1 sleep 2 gotolabel MarinePatrol :MarinePatrol2 ontrigger ChangeMarinePatrol gotolabel MarinePatrol gotoactor PathNode2 gotoactor PathNode3 sleep 2 gotolabel MarinePatrol2

22 Physics Collisions, gravity, falling, explosions, etc. – should be used selectively in your level so as not to overwhelm the engine. NOTE: Don’t confuse with: PYSICS-BASED ANIMATION – the motion of the pawn determines what animation the pawn is playing. – good for multiplayer situations because each client just looks at the motion of a given pawn to see what animation should be playing; no extra information needs to be transmitted.

23 Physics-based Animation walking, running, crouch walking, swimming, flying, jumping, falling, landing, and idling. functionality for playing arbitrary animations not based on movement.

24 Physics-based Animation // Play appropriate idle animations simulated function PlayWaiting(){ if (Physics == PHYS_Falling) LoopAnim(FallingAnim, 1.0, 0.2); else if (Physics == PHYS_Flying) LoopAnim(FlyIdle, 1.0, 0.2); else if (Physics == PHYS_Swimming) LoopAnim(SwimIdle, 1.0, 0.2); else { if (bIsCrouched) LoopAnim(CrouchIdle, 1.0, 0.2); else LoopAnim(StandIdle, 1.0, 0.2); }


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