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InExIn

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Detailed Description

Library for an artificial intelligence in computer games.

At the moment the library provides pathfinding via navigation meshes, organization of AI objects in AI world, actor's decisioning via state machine and basic set of states for actors.

• Coordinate system and units
• Guide to usage
• Examples

Coordinate system and units

AI Lib use right-handed coordinate system. For more information about coordinate systems see DirectX documentation (DirectX Graphics / Programming Guide / 3-D Coordinate Systems and Geometry / 3-D Coordinate systems).

AI Lib has no space units but it is tested on 1 unit = 1 m. Please do not use too little metrics because of possible float rounding errors.

Guide to usage

Even if you can use some classes such as AI_NavigationMesh, AI_AStar or spatial database classes by your own it is the common way how to use the library:

• Create and setup object of AI_World class (or derived).
• Add vertices, edges and triangles into the AI_NavigationMesh of the just created AI_World.
• Preprocess navigation mesh.
• Create and setup agents for your game entities (you can connect them with your entities via setUserData())
  • Use AI_Agent for very little entity without its own intelligence such as for item on the ground.
  • Use AI_Obstacle for bigger entities without its own intelligence when you need your actor to avoid them. For example trees, boxes etc.
  • Use AI_Actor for entities which has some intelligence and need to perform some intelligent behaviour and navigation in the space.
• Create one state machine for each required behaviour. For example close range attacker, long range attacker etc.
• Add one state machine pointer to each AI_Actor object. Actors share state machines and there is no need to create unique SM for each actor.
• Do the agents state reading (position, orientation etc.) and state aplication on game entity.
• Ensure actors feedback (see AI_Actor for more).
• Trigger AI_World per frame.

Examples

World creation

    //create world    
    AI_World world;
    
    //build navigation mesh
    AI_NavigationMesh &navigation_mesh = world.getNavigationMesh();
    
    float           ptr_vertices[];
    unsigned short  ptr_triangles[];
    unsigned short  ptr_edges[];
    
    int i_num_vertices; //num of vertces * 3 (x,y,z)
    int i_num_triangles; // num of triangles * 3 (index vertex1, index vertex2, index vertex3)
    int i_num_edges; //num of edges * 4 (index triangle1, index triangle2, index edge1, index edge2)
    
    loadMeshFromYourFile(ptr_vertices, i_num_vertices, ptr_triangles, i_num_triangles, ptr_edges, i_num_edges);
    
    for (int i=0; i<i_num_vertices; i++)
        navigation_mesh.addVertex( AI_Vector3(ptr_vertices[i], ptr_vertices[i+1], ptr_vertices[i+2]) );

    for (int i=0; i<i_num_triangles; i+3)
        navigation_mesh.addTriangle( ptr_triangles[i], ptr_triangles[i+1], ptr_triangles[i+2]) );

    for (int i=0; i<i_num_edges; i+3)
        navigation_mesh.addEdge( ptr_edges[i], ptr_edges[i+1], ptr_edges[i+2], ptr_edges[i+3] );

    //setup world
    world.setAutoEnable(true);
    world.setAutoEnableDistance(50.0f);

    world.setAutoDisable(true);
    world.setAutoDisableDistance(70.0f);
    
    //this line must be add after the pivot is known and added into the world
    world.setAutoEnableDisablePivot( ptr_agent_pivot );

Actor creation

    //create an actor    
    AI_Actor *ptr_actor = new AI_Actor;
    
    //set characteristics
    ptr_actor->setLinearVelocity( 3.0f );
    ptr_actor->setAngularVelocity( 1.0f );
    ptr_actor->setRefex( 0.2 );
    ptr_actor->setSight( 30.0f );
    ptr_actor->setEarshot( 15.0f );
    ptr_actor->setFOV( 0.785f );
    ptr_actor->setRange( 10.0f );
    ptr_actor->setOptimalDistance( 7.0f );

    //create and set state machine (this state machine consists of one stop state)
    //store state machine pointer and delete them at the end of the game (SM clear all states)
    MUT_AI_StateMachine *ptr_sm = new AI_StateMachine;
    
    ptr_sm->beginStates(1);
    ptr_sm->addState( 0, new AI_Actor::State(0) );
    ptr_sm->endStates();
    
    ptr_actor->setStateMachine( ptr_sm );

    //add into the world
    ptr_actor->AddRef();
    world.addAgent(ptr_actor);

Actor handling

    void YourActorWrapper::readState(void)
    {
        switch ( this->ptr_actor->getAct() )
        {
        case AI_Actor::WALK:
            this->updateActorMovement( this->ptr_actor->getWalkDirection() );
            this->updateActorRotation( this->ptr_actor->getTurnDirection() );
            this->playWalkingAnimation();
            break;
    
        case AI_Actor::TURN:
            this->updateActorRotation( this->ptr_actor->getTurnDirection() );
            this->playTurningAnimation();
            break;
    
        case AI_Actor::ATTACK:
            attackToActor( (YourActorWrapper*)this->ptr_actor->getAttackTarget()->getUserData() );
            this->playAttackAnimation();
            break;
        }        
    }
    
    
    void YourActorWrapper::sendFeedback(void)
    {
        if ( this->isActorMovedSomehow() )
        {
            this->ptr_actor->setPosition( this->getTranslation() );
            this->ptr_actor->setOrientation( this->getEulerAnglesIn0ToPi() );
            this->ptr_actor->move();
        }
        
        if ( this->ptr_actor->getAct()==AI_Actor::ATTACK )
        {
            if ( this->isAttackAnimationFinished() )
            {
                this->ptr_actor->sendFeedback(AI_Actor::ATTACK_FINISHED);
            }
        }
    }

Modules
	Mathematics
	Mathematics library.
	Spatial Database
	Basic spatial database for visibility and spatial region queries.
	Utilities
	Very basic help classes.
Classes
class	AI_Actor
	AI agent as an actor. More...
class	AI_Agent
	Agent in the AI world. More...
class	AI_AStar
	Generic A* (pronounce a-star) algorithm implementation. More...
class	AI_NavigationMesh
	Navigation mesh for agent pathfinding. More...
class	AI_Obstacle
	AI agent as an obstacle. More...
class	AI_State
	One generic state of state machine. More...
class	AI_StateMachine
	Generic state machine. More...
class	AI_World
	World for AI agents. More...

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InExIn documentation generated by doxygen at Tue Dec 18 12:55:28 2007