Code viewer for World: Pac World
// Cloned by J Faj on 27 Oct 2019 from World "Complex World" by Starter user 
// Please leave this clone trail here.


//****************************************************************************** 
//Name : Justin Fajou
//Student Number : 19214107
//
// I implemented the A* algorithm and I also tried 3 additonal things:
//      1. I check for all the possible locations that a good agent can 
//         be trapped and if there are none, then I stop the game immediately, as there will be no solution
//      2. As the goal is the good agent (the end node), when the enemy gets close
//         it doesn't allow it to move very much.  So when this state occurred
//         I selected a random neighbour of the start node to allow the enemy agent
//         to move on and potentially hit a node where it can be trapped
//      3. I also save all the potential nodes for an agent to be trapped and 
//         the corresponding node the enemy agent need to be in to trap the good agent.
//         If the good agent is in one of the "trapped" nodes, and the enemy agent
//         has a neighbour of one of the "winner" nodes, I move the enemy agent to 
//         this node to finish the game quicker
//
// Most of the work is done in the "moveLogicalEnemy" function, but I also created 
// a Node object for each square in the grid.  I also declare some global variables
// and do some initialisation in the "initScene" function.  Finally, I have two smaller
// functions of getDist (the hueristic) and "moveToRandomNeighbour", which covers point 2 above
// 
//
// Some STATS
// I ran both algorithms 20 times (original vs. new A*).  For those searches that didn't find the good agent, I've used 1000 steps as 
// the result:
// Average steps for Original : 716
// Average steps for new A* : 477
//
// In addition, the Original search found the good agent 50% of the time versus the A* which found the agent 65% of the time
//
// Certainly a decrease in the number of steps to find the good agent, but not quite as dramatic as I'd hoped.
// In retrosepct, there were two types of targets.  The good agent, and the squares where the good agent could be trapped.
// An algorithm that could "lure" the good agent into one of those squares is something I would have looked at, which
// could have dramatically increased the success rate of trapping the good agent.  It would have also increased the complexity
// and coding it in such a way that it was fast enough may have been a challenge.
//
//
//Finally, one of the final things you mentioned in your email was some analysis on what they agent could do to counter.
//I think the biggest think it could do would be to become aware of the locations on the grid where it can be trapped and
//design its moves to avoid those locations.  Would become close to impossible for the enemy agent to trap it then
//******************************************************************************

// ==== Starter World ===============================================================================================
// (c) Ancient Brain Ltd. All rights reserved.
// This code is only for use on the Ancient Brain site.
// This code may be freely copied and edited by anyone on the Ancient Brain site.
// This code may not be copied, re-published or used on any other website.
// To include a run of this code on another website, see the "Embed code" links provided on the Ancient Brain site.
// ==================================================================================================================



// =============================================================================================
// More complex starter World 
// 3d-effect Maze World (really a 2-D problem)
// Movement is on a semi-visible grid of squares 
//
// This more complex World shows:
// - Skybox
// - Internal maze (randomly drawn each time)
// - Enemy actively chases agent
// - Music/audio
// - 2D world (clone this and set show3d = false)
// - User keyboard control (clone this and comment out Mind actions to see)
// =============================================================================================


// =============================================================================================
// Scoring:
// Bad steps = steps where enemy is within one step of agent.
// Good steps = steps where enemy is further away. 
// Score = good steps as percentage of all steps.
//
// There are situations where agent is trapped and cannot move.
// If this happens, you score zero.
// =============================================================================================


 





// ===================================================================================================================
// === Start of tweaker's box ======================================================================================== 
// ===================================================================================================================

// The easiest things to modify are in this box.
// You should be able to change things in this box without being a JavaScript programmer.
// Go ahead and change some of these. What's the worst that could happen?


AB.clockTick       = 100;    

	// Speed of run: Step every n milliseconds. Default 100.
	
AB.maxSteps        = 1000;    

	// Length of run: Maximum length of run in steps. Default 1000.

AB.screenshotStep  = 50;   
  
	// Take screenshot on this step. (All resources should have finished loading.) Default 50.



//---- global constants: -------------------------------------------------------

 const show3d = true;						// Switch between 3d and 2d view (both using Three.js) 


 //const TEXTURE_WALL 	= '/uploads/starter/door.jpg' ;
 const TEXTURE_WALL 	= '/uploads/jfajou/TronCircuitry.jpg' ;
 const TEXTURE_MAZE 	= '/uploads/jfajou/TronVector.jpg' ;
 //const TEXTURE_MAZE 	= '/uploads/starter/latin.jpg' ;
 const TEXTURE_AGENT 	= '/uploads/starter/pacman.jpg' ;
 //const TEXTURE_ENEMY 	= '/uploads/starter/ghost.3.png' ;
 const TEXTURE_ENEMY 	= '/uploads/jfajou/Ghost.jpg' ;

// credits:
// http://commons.wikimedia.org/wiki/File:Old_door_handles.jpg
// https://commons.wikimedia.org/wiki/Category:Pac-Man_icons
// https://commons.wikimedia.org/wiki/Category:Skull_and_crossbone_icons
// http://en.wikipedia.org/wiki/File:Inscription_displaying_apices_(from_the_shrine_of_the_Augustales_at_Herculaneum).jpg

 
	const MUSIC_BACK  = '/uploads/starter/Defense.Line.mp3' ;
	const SOUND_ALARM = '/uploads/starter/air.horn.mp3' ;

// credits:
// http://www.dl-sounds.com/royalty-free/defense-line/
// http://soundbible.com/1542-Air-Horn.html 

	
	
const gridsize = 20;						// number of squares along side of world	   

const NOBOXES =  Math.trunc ( (gridsize * gridsize) / 10 );
		// density of maze - number of internal boxes
		// (bug) use trunc or can get a non-integer 

const squaresize = 100;					// size of square in pixels

const MAXPOS = gridsize * squaresize;		// length of one side in pixels 
	
const SKYCOLOR 	= 0xddffdd;				// a number, not a string 

 
const startRadiusConst	 	= MAXPOS * 0.8 ;		// distance from centre to start the camera at
const maxRadiusConst 		= MAXPOS * 10  ;		// maximum distance from camera we will render things  



//--- change ABWorld defaults: -------------------------------

ABHandler.MAXCAMERAPOS 	= maxRadiusConst ;

ABHandler.GROUNDZERO		= true;						// "ground" exists at altitude zero



//--- skybox: -------------------------------
// skybox is a collection of 6 files 
// x,y,z positive and negative faces have to be in certain order in the array 
// https://threejs.org/docs/#api/en/loaders/CubeTextureLoader 

// mountain skybox, credit:
// http://stemkoski.github.io/Three.js/Skybox.html
/*
 const SKYBOX_ARRAY = [										 
                "/uploads/starter/dawnmountain-xpos.png",
                "/uploads/starter/dawnmountain-xneg.png",
                "/uploads/starter/dawnmountain-ypos.png",
                "/uploads/starter/dawnmountain-yneg.png",
                "/uploads/starter/dawnmountain-zpos.png",
                "/uploads/starter/dawnmountain-zneg.png"
                ];

*/
// space skybox, credit:
// http://en.spaceengine.org/forum/21-514-1
// x,y,z labelled differently


 const SKYBOX_ARRAY = [										 
                "/uploads/starter/sky_pos_z.jpg",
                "/uploads/starter/sky_neg_z.jpg",
                "/uploads/starter/sky_pos_y.jpg",
                "/uploads/starter/sky_neg_y.jpg",
                "/uploads/starter/sky_pos_x.jpg",
                "/uploads/starter/sky_neg_x.jpg"
                ];
				


// urban photographic skyboxes, credit:
// http://opengameart.org/content/urban-skyboxes

/*
 const SKYBOX_ARRAY = [										 
                "/uploads/starter/posx.jpg",
                "/uploads/starter/negx.jpg",
                "/uploads/starter/posy.jpg",
                "/uploads/starter/negy.jpg",
                "/uploads/starter/posz.jpg",
                "/uploads/starter/negz.jpg"
                ];
*/



// ===================================================================================================================
// === End of tweaker's box ==========================================================================================
// ===================================================================================================================


// You will need to be some sort of JavaScript programmer to change things below the tweaker's box.

//--- Mind can pick one of these actions -----------------

const ACTION_LEFT 			= 0;		   
const ACTION_RIGHT 			= 1;
const ACTION_UP 			= 2;		 
const ACTION_DOWN 			= 3;
const ACTION_STAYSTILL 		= 4;

// in initial view, (smaller-larger) on i axis is aligned with (left-right)
// in initial view, (smaller-larger) on j axis is aligned with (away from you - towards you)


// contents of a grid square

const GRID_BLANK 	= 0;
const GRID_WALL 	= 1;
const GRID_MAZE 	= 2;
 
 
var BOXHEIGHT;		// 3d or 2d box height 

var GRID 	= new Array(gridsize);			// can query GRID about whether squares are occupied, will in fact be initialised as a 2D array   

var theagent, theenemy;
  
var wall_texture, agent_texture, enemy_texture, maze_texture; 


// enemy and agent position on squares
var ei, ej, ai, aj;

var badsteps;
var goodsteps;

//**************************************************************
//New Variables for A* Search

// Start and End Nodes
var startNode;
var endNode;

//This is all the places on the grid where the good agent can be trapped
var trappedSet = [];

//This is all the places on the grid where the enemy agent needs to be
//to trap the good agent, but only if it's in the corresponding trappedSet
var winnerSet = [];

//If there is no square for the agent to be trapped, then stop
//the game immediately
var isASolution = false;

//Could have used the GRID array, but decided to keep it separate from the
//existing code
var grid = new Array(gridsize);

//**************************************************************


function loadResources()		// asynchronous file loads - call initScene() when all finished 
{
	var loader1 = new THREE.TextureLoader();
	var loader2 = new THREE.TextureLoader();
	var loader3 = new THREE.TextureLoader();
	var loader4 = new THREE.TextureLoader();
	
	loader1.load ( TEXTURE_WALL, function ( thetexture )  		
	{
		thetexture.minFilter  = THREE.LinearFilter;
		wall_texture = thetexture;
		if ( asynchFinished() )	initScene();		// if all file loads have returned 
	});
		
	loader2.load ( TEXTURE_AGENT, function ( thetexture )  	 
	{
		thetexture.minFilter  = THREE.LinearFilter;
		agent_texture = thetexture;
		if ( asynchFinished() )	initScene();		 
	});	
	
	loader3.load ( TEXTURE_ENEMY, function ( thetexture )  
	{
		thetexture.minFilter  = THREE.LinearFilter;
		enemy_texture = thetexture;
		if ( asynchFinished() )	initScene();		 
	});
	
	loader4.load ( TEXTURE_MAZE, function ( thetexture )  
	{
		thetexture.minFilter  = THREE.LinearFilter;
		maze_texture = thetexture;
		if ( asynchFinished() )	initScene();		 
	});
	
}


function asynchFinished()		 // all file loads returned 
{
	if ( wall_texture && agent_texture && enemy_texture && maze_texture )   return true; 
	else return false;
}	
	
	
 
//--- grid system -------------------------------------------------------------------------------
// my numbering is 0 to gridsize-1

	
function occupied ( i, j )		// is this square occupied
{
 if ( ( ei == i ) && ( ej == j ) ) return true;		// variable objects 
 if ( ( ai == i ) && ( aj == j ) ) return true;

 if ( GRID[i][j] == GRID_WALL ) return true;		// fixed objects	 
 if ( GRID[i][j] == GRID_MAZE ) return true;		 
	 
 return false;
}

 
// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates
// logically, coordinates are: y=0, x and z all positive (no negative)    
// logically my dimensions are all positive 0 to MAXPOS
// to centre everything on origin, subtract (MAXPOS/2) from all dimensions 

function translate ( i, j )			
{
	var v = new THREE.Vector3();
	
	v.y = 0;	
	v.x = ( i * squaresize ) - ( MAXPOS/2 );   		 
	v.z = ( j * squaresize ) - ( MAXPOS/2 );   	
	
	return v;
}

	
function initScene()		// all file loads have returned 
{
	 var i,j, shape, thecube;
	 
	// set up GRID as 2D array
	 
	 for ( i = 0; i < gridsize ; i++ ) 
		GRID[i] = new Array(gridsize);		 

	// set up walls
	 
	 for ( i = 0; i < gridsize ; i++ ) 
	  for ( j = 0; j < gridsize ; j++ ) 
		if ( ( i==0 ) || ( i==gridsize-1 ) || ( j==0 ) || ( j==gridsize-1 ) )
		{
			GRID[i][j] = GRID_WALL;		 
			shape    = new THREE.BoxGeometry ( squaresize, BOXHEIGHT, squaresize );			 
			thecube  = new THREE.Mesh( shape );
			thecube.material = new THREE.MeshBasicMaterial( { map: wall_texture } );
			
			thecube.position.copy ( translate(i,j) ); 		  	// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates 
			ABWorld.scene.add(thecube);
		}
		else 
   			GRID[i][j] = GRID_BLANK;

		
   // set up maze 
   
    for ( var c=1 ; c <= NOBOXES ; c++ )
	{
		i = AB.randomIntAtoB(1,gridsize-2);		// inner squares are 1 to gridsize-2
		j = AB.randomIntAtoB(1,gridsize-2);
			
		GRID[i][j] = GRID_MAZE ;
		
		shape    = new THREE.BoxGeometry ( squaresize, BOXHEIGHT, squaresize );			 
		thecube  = new THREE.Mesh( shape );
		thecube.material = new THREE.MeshBasicMaterial( { map: maze_texture } );		  

		thecube.position.copy ( translate(i,j) ); 		  	// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates 
		ABWorld.scene.add(thecube);		
	}
	 	 
   
	// set up enemy 
	// start in random location
	 do
	 {
	  i = AB.randomIntAtoB(1,gridsize-2);
	  j = AB.randomIntAtoB(1,gridsize-2);
	 }
	 while ( occupied(i,j) );  	  // search for empty square 

	 ei = i;
	 ej = j;
	 
	 shape    = new THREE.BoxGeometry ( squaresize, BOXHEIGHT, squaresize );			 
	 theenemy = new THREE.Mesh( shape );
 	 theenemy.material =  new THREE.MeshBasicMaterial( { map: enemy_texture } );
	 ABWorld.scene.add(theenemy);
	 drawEnemy();		  

	// set up agent 
	// start in random location
	 do
	 {
	  i = AB.randomIntAtoB(1,gridsize-2);
	  j = AB.randomIntAtoB(1,gridsize-2);
	 }
	 while ( occupied(i,j) );  	  // search for empty square 

	 ai = i;
	 aj = j;
 
	 shape    = new THREE.BoxGeometry ( squaresize, BOXHEIGHT, squaresize );			 
	 theagent = new THREE.Mesh( shape );
	 theagent.material =  new THREE.MeshBasicMaterial( { map: agent_texture } );
	 ABWorld.scene.add(theagent);
	 drawAgent(); 

  // finally skybox 
  // setting up skybox is simple 
  // just pass it array of 6 URLs and it does the asych load 
  
  	 ABWorld.scene.background = new THREE.CubeTextureLoader().load ( SKYBOX_ARRAY, 	function() 
	 { 
		ABWorld.render(); 
	 
		AB.removeLoading();
	
		AB.runReady = true; 		// start the run loop
	 });

//****************************************************
//Initialise the grid array for the A* search 

    // Making a 2D array
    for (var i = 0; i < gridsize; i++) 
        grid[i] = new Array(gridsize);
        
    for (var i = 0; i < gridsize; i++) 
        for (var j = 0; j < gridsize; j++) 
            grid[i][j] = new Node(i, j);

    // All the neighbors
    for (var i = 0; i < gridsize; i++) 
        for (var j = 0; j < gridsize; j++) 
            {
                grid[i][j].addNeighbors(grid);
                if (grid[i][j].canBeStoppedHere == true) isASolution = true;
            }

    if (isASolution == false)
    {
        AB.abortRun = true;
        console.log("There is no square available for the agent to be trapped, so we can finish here!");
    }
//***************************************************	 
	
}
 
 
// --- draw moving objects -----------------------------------
function drawEnemy()		// given ei, ej, draw it 
{
	theenemy.position.copy ( translate(ei,ej) ); 		  	// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates 

	ABWorld.lookat.copy ( theenemy.position );	 		// if camera moving, look back at where the enemy is  
}

function drawAgent()		// given ai, aj, draw it 
{
	theagent.position.copy ( translate(ai,aj) ); 		  	// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates 

	ABWorld.follow.copy ( theagent.position );			// follow vector = agent position (for camera following agent)
}


// --- take actions -----------------------------------
//Implementation of A* search ------------------
//*************************************************************************
function Node(i, j) 
{

    // Location
    this.i = i;
    this.j = j;

    // f, g, and h values for A*
    //this.f = 0;
    this.g = 0;
    this.h = 0;
    this.f = this.g + this.h;

  // Neighbors
  this.neighbors = [];

  // Where did I come from?
  this.previous = undefined;

  //Check for Wall
 if ( GRID[i][j] == GRID_BLANK ) 
    this.wall = false;		// fixed objects	 
 else 
    this.wall = true;
    
  //Can be caught
  this.canBeStoppedHere = false;

  // Figure out who my neighbors are
  this.addNeighbors = function(grid) 
  {
    var i = this.i;
    var j = this.j;
    var k = 0;
    var temp;
    
    if (i < gridsize - 1)
        {
            this.neighbors.push(grid[i + 1][j]);
            if (grid[i + 1][j].wall == true) k++;
            else temp = grid[i + 1][j];
        }
    if (i > 0)
        {
            this.neighbors.push(grid[i - 1][j]);
            if (grid[i - 1][j].wall == true) k++;
            else temp = grid[i - 1][j];
        }
    if (j < gridsize - 1)
        {
            this.neighbors.push(grid[i][j + 1]);
            if (grid[i][j + 1].wall == true) k++;
            else temp = grid[i][j + 1];
        }
    if (j > 0)
        {
            this.neighbors.push(grid[i][j - 1]);
            if (grid[i][j - 1].wall == true) k++;
            else temp = grid[i][j - 1];
        }
    
    //The logic here is to determine whether there are any nodes where the good agent can be stopped
    //If there are 3 (and only 3) neighbours that are walls that are not diagonal, then this node
    //will allow the good agent to be trapped.
    //It currently won't cater for when this Node is inaccessible by the good agent, but if none exist,
    //then there is definitely no solution and the game can be stopped.
    if (k == 3 && grid[i][j].wall == false)
    {
        console.log("***Can be stopped at " + i + ", " + j);
        this.canBeStoppedHere = true;
        trappedSet.push(grid[i][j]);
        winnerSet.push(temp);
    }
    
    if (i > 0 && j > 0)                 this.neighbors.push(grid[i - 1][j - 1]);
    if (i < gridsize - 1 && j > 0)          this.neighbors.push(grid[i + 1][j - 1]);
    if (i > 0 && j < gridsize - 1)          this.neighbors.push(grid[i - 1][j + 1]);
    if (i < gridsize - 1 && j < gridsize - 1)   this.neighbors.push(grid[i + 1][j + 1]);
    
  }
  
}

function getDist (a,b)
{
    //I eventually worked out that there is a Distance function in three.js, but I left this
    //as it should be doing the same job
    var dist =  Math.pow((a.i - b.i),2) + Math.pow((a.j - b.j),2);
    //console.log("Dist is " + dist);
    return Math.sqrt(dist);
    
}

function moveLogicalEnemy()
{ 
    //All the logic for the A* search is in this function
    
    // Open and closed set
    var openSet = [];
    var closedSet = [];

    var current;

    startNode = grid[ei][ej];
    endNode = grid[ai][aj];
    
    //console.log("Trapped Set is " + trappedSet.length);
    //console.log("Winner Set is " + winnerSet.length);
    
    openSet.push(startNode);

    //Continue searching while there is anything left in the openSet
    while (openSet.length > 0)
    {
        // Best next option
        var winner = 0;
    
        for (var i = 0; i < openSet.length; i++) 
            if (openSet[i].f < openSet[winner].f) 
                winner = i;
        
        current = openSet[winner];
        if (current == endNode)
        {   
            //console.log("About to break at " + endNode.i + "," + endNode.j);
            break;
        }
        
        //Remove the Node from openSet, as it's about to be searched
        for (var i = openSet.length - 1; i >= 0; i--) 
            if (openSet[i] == current) 
                openSet.splice(i, 1);
        
        //Add to closedSet        
        closedSet.push(current);
        
        // Check all the neighbors
        var neighbors = current.neighbors;
        //console.log("Number of neighbours is " + neighbors.length);
        for (var i = 0; i < neighbors.length; i++) 
        {
            var neighbor = neighbors[i];
            
            // If the neighbour has not been searched and isn't part of the maze, then check it
            if (!closedSet.includes(neighbor) && !neighbor.wall) 
            {
                var tempG = current.g + getDist(neighbor, current);

                // Is this a better path than before?
                var newPath = false;
                if (openSet.includes(neighbor)) 
                {
                    if (tempG < neighbor.g) 
                    {
                        neighbor.g = tempG;
                        newPath = true;
                    }
                }
                else 
                {
                    neighbor.g = tempG;
                    newPath = true;
                    openSet.push(neighbor);
                }

                // Yes, it's a better path
                if (newPath) 
                {
                    //No need to set f here, as it's set as part of the Node object
                    neighbor.h = getDist(neighbor, endNode);
                    neighbor.previous = current;
                }
            }
        }
    }

    var temp = current;
    var z = 0;
    while (temp.previous)
    {
        z++;
        if (temp.previous == startNode)
            break;
        temp = temp.previous;
    }
//    console.log("Count through while is " + z);

    //If the node isn't equal to the endNode, then assign the co-ordinates, 
    //otherwise there two further options if the new search is the endNode.
    //There is a more detailed explanation at the top of the program which details
    //what I'm doing here.
    if (temp !== endNode)
    {
        ei = temp.i;
        ej = temp.j;
    }
    else
    {
        if (trappedSet.includes(endNode))
        {
            var newNode = winnerSet[trappedSet.indexOf(endNode)];
            if (startNode.neighbors.includes(newNode))
            {
                console.log("*****In the TRAP!!!!");
                console.log("Winner location " + trappedSet.indexOf(endNode));
                ei = newNode.i;
                ej = newNode.j;
            }
            else
                moveToRandomNeighbour();
        }
        else
            moveToRandomNeighbour();
    }
}

function moveToRandomNeighbour()
{
    //Randomly select a Node from the neighbours array 
    //as long as it's not a wall, maze, or the good agent
    //As we know that the next node is the endNode, we can use the 
    //a neighbour of the startNode to encourage the agent
    //to move to another node
    //The reason I had to do this is because I originally just had the 
    //if statement above, and when the enemy agent was close to the good agent
    //the next move was mostly the endNode, and started the A* again
    //By selecting a random neighbour of startNode, this allowed the good agent to
    //move more freely and made it more likely to trap the good agent
    var i;
    var newNode = startNode.neighbors;
	do
	{   
	    i = AB.randomIntAtoB(0,newNode.length-1);
	}
	while ( occupied(newNode[i].i, newNode[i].j) ); 
        
    ei = newNode[i].i;
    ej = newNode[i].j;
    console.log("New end Node is " + ei + "," + ej);
}

function moveLogicalAgent( a )			// this is called by the infrastructure that gets action a from the Mind 
{ 
 var i = ai;
 var j = aj;		 

      if ( a == ACTION_LEFT ) 	i--;
 else if ( a == ACTION_RIGHT ) 	i++;
 else if ( a == ACTION_UP ) 		j++;
 else if ( a == ACTION_DOWN ) 	j--;

 if ( ! occupied(i,j) ) 
 {
  ai = i;
  aj = j;
 }
}




// --- key handling --------------------------------------------------------------------------------------
// This is hard to see while the Mind is also moving the agent:
// AB.mind.getAction() and AB.world.takeAction() are constantly running in a loop at the same time 
// have to turn off Mind actions to really see user key control 

// we will handle these keys: 

var OURKEYS = [ 37, 38, 39, 40 ];

function ourKeys ( event ) { return ( OURKEYS.includes ( event.keyCode ) ); }
	

function keyHandler ( event )		
{
	if ( ! AB.runReady ) return true; 		// not ready yet 

   // if not one of our special keys, send it to default key handling:
	
	if ( ! ourKeys ( event ) ) return true;
	
	// else handle key and prevent default handling:
	
	if ( event.keyCode == 37 )   moveLogicalAgent ( ACTION_LEFT 	);   
    if ( event.keyCode == 38 )   moveLogicalAgent ( ACTION_DOWN  	); 	 
    if ( event.keyCode == 39 )   moveLogicalAgent ( ACTION_RIGHT 	); 	 
    if ( event.keyCode == 40 )   moveLogicalAgent ( ACTION_UP		);   
	
	// when the World is embedded in an iframe in a page, we want arrow key events handled by World and not passed up to parent 

	event.stopPropagation(); event.preventDefault(); return false;
}





// --- score: -----------------------------------


function badstep()			// is the enemy within one square of the agent
{
 if ( ( Math.abs(ei - ai) < 2 ) && ( Math.abs(ej - aj) < 2 ) ) return true;
 else return false;
}


function agentBlocked()			// agent is blocked on all sides, run over
{
 return ( 	occupied (ai-1,aj) 		&& 
		occupied (ai+1,aj)		&&
		occupied (  ai,aj+1)		&&
		occupied (  ai,aj-1) 	);		
} 


function updateStatusBefore(a)
// this is called before anyone has moved on this step, agent has just proposed an action
// update status to show old state and proposed move 
{
 var x 		= AB.world.getState();
 AB.msg ( " Step: " + AB.step + " &nbsp; x = (" + x.toString() + ") &nbsp; a = (" + a + ") " ); 
}


function   updateStatusAfter()		// agent and enemy have moved, can calculate score
{
 // new state after both have moved
 
 var y 		= AB.world.getState();
 var score = ( goodsteps / AB.step ) * 100; 

 AB.msg ( " &nbsp; y = (" + y.toString() + ") <br>" +
		" Bad steps: " + badsteps + 
		" &nbsp; Good steps: " + goodsteps + 
		" &nbsp; Score: " + score.toFixed(2) + "% ", 2 ); 
}





AB.world.newRun = function() 
{
	AB.loadingScreen();

	AB.runReady = false;  

	badsteps = 0;	
	goodsteps = 0;

	
	if ( show3d )
	{
	 BOXHEIGHT = squaresize;
	 ABWorld.init3d ( startRadiusConst, maxRadiusConst, SKYCOLOR  ); 	
	}	     
	else
	{
	 BOXHEIGHT = 1;
	 ABWorld.init2d ( startRadiusConst, maxRadiusConst, SKYCOLOR  ); 		     
	}
	
	
	loadResources();		// aynch file loads		
							// calls initScene() when it returns 

	document.onkeydown = keyHandler;	
		 
};



AB.world.getState = function()
{
 var x = [ ai, aj, ei, ej ];
  return ( x );  
};



AB.world.takeAction = function ( a )
{
  updateStatusBefore(a);			// show status line before moves 

  moveLogicalAgent(a);

  if ( ( AB.step % 2 ) == 0 )		// slow the enemy down to every nth step
    moveLogicalEnemy();


  if ( badstep() )  badsteps++;
  else   			goodsteps++;

   drawAgent();
   drawEnemy();
   updateStatusAfter();			// show status line after moves  


  if ( agentBlocked() )			// if agent blocked in, run over 
  {
	AB.abortRun = true;
	goodsteps = 0;			// you score zero as far as database is concerned 			 
	musicPause();
	soundAlarm();
  }

};



AB.world.endRun = function()
{
  musicPause(); 
  if (isASolution == false)
  {
      AB.msg ( " <br> <font color=red> <B> The Agent cannot be trapped. The game has ended. </B> </font>   ", 3  );
  }
  else
  {
    if ( AB.abortRun ) AB.msg ( " <br> <font color=red> <B> Agent trapped. Final score zero. </B> </font>   ", 3  );
      else    				AB.msg ( " <br> <font color=green> <B> Run over. </B> </font>   ", 3  );
  }
};

 
AB.world.getScore = function()
{
    // only called at end - do not use AB.step because it may have just incremented past AB.maxSteps
    
    var s = ( goodsteps / AB.maxSteps ) * 100;   // float like 93.4372778 
    var x = Math.round (s * 100);                // 9344
    return ( x / 100 );                          // 93.44
};


 




// --- music and sound effects ----------------------------------------

var backmusic = AB.backgroundMusic ( MUSIC_BACK );

function musicPlay()   { backmusic.play();  }
function musicPause()  { backmusic.pause(); }

											 
function soundAlarm()
{
	var alarm = new Audio ( SOUND_ALARM );
	alarm.play();							// play once, no loop 
}