Code viewer for World: Complex World-II Aparna (c...
/***
Name: Aparna Cheriya Mullamparambath
Email: aparna.cheriyamullamparambath2@mail.dcu.ie
Student Number: 22267019
***/
// Cloned by Aparna on 4 Nov 2022 from World "Complex World" by Starter user 
// Please leave this clone trail here.
 



// ==== Starter World =================================================================================================
// This code is designed for use on the Ancient Brain site.
// This code may be freely copied and edited by anyone on the Ancient Brain site.
// To include a working run of this program on another site, see the "Embed code" links provided on Ancient Brain.
// ====================================================================================================================



// =============================================================================================
// 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       = 200 ; // 500;    

	// 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 WALLMOVENO = 20; // 60;
 const WALLMOVETICK = 2;

 
 const TEXTURE_WALL 	= '/uploads/aparna/wallBlack.png' ;
 const TEXTURE_MAZE 	= 'uploads/aparna/maze.png' ;
 const TEXTURE_AGENT 	= '/uploads/starter/pacman.jpg' ;
 const TEXTURE_ENEMY 	= '/uploads/aparna/Hazard.png' ;

// const TEXTURE_ENEMY 	= '/uploads/aparna/Death_BlackWhight.png' ;
// credits:
// https://commons.wikimedia.org/wiki/File:DmhImg3333.png
// https://commons.wikimedia.org/wiki/File:Red_lego_brick.png
// https://commons.wikimedia.org/wiki/Category:Skull_and_crossbone_icons
// https://commons.wikimedia.org/wiki/File:ECB_Hazard_Symbol_T.svg
// https://commons.wikimedia.org/wiki/File:Death_penalty.svg
 
	const MUSIC_BACK  = 'uploads/aparna/Komiku_-_29_-_Poupi_Great_Adventures_The_Arcade_Game.ogg.mp3' ;
	const SOUND_ALARM = '/uploads/aparna/Alarm_or_siren.ogg.mp3' ;

// credits:
//https://commons.wikimedia.org/wiki/File:Komiku_-_07_-_STOP_TALKING_AND_MOVING_Games_Mascotts_theme.ogg
//https://upload.wikimedia.org/wikipedia/commons/transcoded/8/81/Alarm_or_siren.ogg/Alarm_or_siren.ogg.mp3

	
	
const gridsize = 40; // 20;						// number of squares along side of world	   

 const NOBOXES =  Math.trunc ( (gridsize * gridsize) / 3 );  // 10 
// const NOBOXES = 100;
		// 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 PATHCOLOR = 0xff0000;            // a number, not a string 
 
const startRadiusConst	 	= MAXPOS * 1 ;		// 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/aparna/posx.jpg",
	"/uploads/aparna/negx.jpg",
	"/uploads/aparna/posy.jpg",
	"/uploads/aparna/negy.jpg",
	"/uploads/aparna/posz.jpg",
	"/uploads/aparna/negz.jpg"
	];
//credits
//https://opengameart.org/content/field-skyboxes
// ===================================================================================================================
// === 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, thepath;
  
var wall_texture, agent_texture, enemy_texture, maze_texture; 

var start, end 

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

var badsteps;
var goodsteps;

var openSet = [];
var closedSet = [];
var path = [];
var pathCube = [];
var wallPositions = [];


/**
 * Find an element and remove it from the array.
 * @param {array} array 
 * @param {object} element 
 */
function removeFromArray(array, element) 
{
  const index = array.indexOf(element);
  // Here we assume that element always exist in the array.
  array.splice(index, 1);
}

/**
 * Represents heuristic used in A* algorithm.
 * Since diagonal movement is not allowed, use Manhattan distance.
 * @param {object} a 
 * @param {object} b 
 * @returns {number}
 */
function heuristic ( a, b ) 
{
	// Use Manhattan distance as heuristic  
	// since diagonal move is not allowed.
    return ( Math.abs(a.i - b.i) + Math.abs(a.j - b.j) );
}
/**
 * Compute G function in A* algorithm.
 * Since diagonal movement is not allowed, maximum value will be 1.
 * @param {object} a 
 * @param {object} b 
 * @returns {number}
 */
function computeG  ( a, b ) 
{
    return ( Math.abs(a.i - b.i) + Math.abs(a.j - b.j) ); 
}
/**
 * Find the optimal path from enemy to agent. 
 */
function findNextStep()
{
	var i;
	var j;
	// Reset f, g and h values of all cells in the grid.
	// This is required for running A* algorithm
	for (i = 0; i < gridsize; i++) 
		for (j = 0; j < gridsize; j++) 
			GRID[i][j].resetState(GRID);
	// Find the neighbors of each cell. 
	// This will be used in A*
	for (i = 0; i < gridsize; i++) 
		for (j = 0; j < gridsize; j++) 
			GRID[i][j].addNeighbors(GRID)
    	// reset path for finding the new path.
	path = [];
	var finalNode = runAStar();

	if(finalNode != null)
	{
		// Find the path by working backwards		
		var temp = finalNode;
		path.push(temp);
		while (temp.previous) 
		{
		  path.push(temp.previous);
		  temp = temp.previous;
		}
	}
}

// --- run A* -----------------------------
/**
 * Run A* algorithm to find the optimal path between the enemey and the agent
 * @returns agent if path exists, else return null
 */
function runAStar()
{
    var i;
	openSet = [];
	closedSet = [];
	var x  = AB.world.getState();
	start = GRID[ei][ej];
	end = GRID[ai][aj];	
	openSet.push(start);
	while (openSet.length > 0)
	{
		var winner = 0;
		
       // Find the node with least f value from the openset.
		
		for (i = 0; i < openSet.length; i++)
		{
		    if (openSet[i].f < openSet[winner].f) 
			    winner = i;
		}
		

		var current = openSet[winner];
		if (current === end) 
		{
		  //Algorithm ends on the target node.
		  console.log("***** Found optimal path *****");
		  return current;
		}

		removeFromArray(openSet, current);
    	closedSet.push(current);

		var neighbors = current.neighbors;
		for (i = 0; i < neighbors.length; i++)
		{
			var neighbor = neighbors[i];
			// Consider node which is not closed and not wall
			if (!closedSet.includes(neighbor) && neighbor.cellType != GRID_MAZE)
			{
				
				var g = current.g + computeG ( neighbor, current );
				var newPath = false;
				// Check for a better path than what we have now.
				if (openSet.includes(neighbor)) 
				{
					
					if (g < neighbor.g) 
					{
						neighbor.g = g;
						newPath = true;
					}
				}
				else 
				{
					neighbor.g = g;
					newPath = true;
					openSet.push(neighbor);
				}

				// Calculate new f, g and h values
				if (newPath) 
				{	
				  neighbor.h = heuristic ( neighbor, end );
				  neighbor.f = neighbor.g + neighbor.h;
				  neighbor.previous = current;
				}
			}			
		}
	}
	// No optimal path exist between enemy and agent.
	return null;
}
/**
 * Load resources at start up
 */
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();		 
	});
	
}

/**
 * Check whether all files are loaded.
 * @returns {bool}
 */
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

/**
 * Check whether the square is occupied
 * @param {number} i 
 * @param {number} j 
 * @returns {bool}
 */
	
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].cellType == GRID_WALL ) return true;		// fixed objects	 
 if ( GRID[i][j].cellType == GRID_MAZE ) return true;		 
	 
 return false;
}

/**
 * Check whether the cell is Enemy.
 * @param {number} i 
 * @param {number} j 
 * @returns {bool}
 */
function isEnemy(i, j)
{
	if ( ( ei == i ) && ( ej == j ) ) return true;
}

/**
 * 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 
 * @param {number} i 
 * @param {number} j 
 * @returns {object}
 */
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;
}

/**
 * Generate integer random numbers between begin and end.
 * @param {number} begin 
 * @param {number} end 
 * @param {number} count 
 * @returns Array of random numbers
 */
function getNRandomNumbers(begin, end, count)
{
    var set = new Set();
    var more = count;
    while(more > 0)
    {
        var num = AB.randomIntAtoB(begin, end);
		// Generate unique random numbers.
        if(!set.has(num)) 
        {
            set.add(num);
            more--;
        }
    }
    return Array.from(set);
}

/**
 * Replace WALLMOVENO number of walls with new walls
 */
function findWallPositionsToChange()
{
    var wallsToKeep = null;
    var wallsToChange = null;
    var indexStore = []; // Stores the position of new walls.

	// The array wallPositions maintains the i, j indices of all the existing walls.
	// We need to randomly select which walls in the grid should be removed, 
	// by selecting the indexes of wallPostions array. 
	// If total walls to be moved is more than half of the total number of walls,
	// then randomly select which walls to kept instead of walls to be removed,
	// this would reduce the number of unique random numbers to be found.
    if(WALLMOVENO > wallPositions.length / 2)
    {
        wallsToKeep = getNRandomNumbers(0, wallPositions.length - 1, wallPositions.length - WALLMOVENO);
    }
    else 
    {        
        wallsToChange = getNRandomNumbers(0, wallPositions.length - 1, WALLMOVENO);
    }
    if(wallsToKeep != null)
    {
        // Select wallPositions.length - wallsToKeep random positions
        var more = wallPositions.length - wallsToKeep.length;
        var i, j;
        while(more > 0)
        {
            i = AB.randomIntAtoB(1,gridsize-2);		// inner squares are 1 to gridsize-2
		    j = AB.randomIntAtoB(1,gridsize-2);
			// Select unoccupied and unique i and j combinations
            if(!occupied(i, j) && !indexStore.some(e => e.i === i && e.j === j))
            {
                more--;
                indexStore.push({"i": i, "j": j});
            }
        }
		// Since we identified the positions of the walls to be kept as it is, 
		// now need to find the position of walls to be removed.
		// Suppose we have total 6 walls [0, 1, 2, 3, 4, 5, 6] and walls to keep are [3, 5],
		// then walls to be removed are [0, 1, 2, 4, 6].
		// Following two lines would do it    
        var temp = Array.from(Array(wallPositions.length).keys())
        wallsToChange = temp.filter(x => !wallsToKeep.includes(x));
		// Finally remove the walls and add new walls.
		removeBoxAndAddNewBoxesToScene(wallPositions, wallsToChange, indexStore);
    }
    else
    {     
        var more = wallsToChange.length;
        var i, j;
        while(more > 0)
        {
            i = AB.randomIntAtoB(1,gridsize-2);		// inner squares are 1 to gridsize-2
		    j = AB.randomIntAtoB(1,gridsize-2);
			// Select unoccupied and unique i and j combinations
            if(!occupied(i, j) && !indexStore.some(e => e.i === i && e.j === j))
            {
                more--;
                indexStore.push({"i": i, "j": j});
            }
        }
		// Remove the walls and add new walls.
        removeBoxAndAddNewBoxesToScene(wallPositions, wallsToChange, indexStore);      
    }
}

/**
 * Remove selected walls and add new walls.
 * @param {array} wallPositions - stores the existing walls and its i, j indices
 * @param {array} wallsToChange - index of walls to be changed/removed
 * @param {array} indexStore - postion of new walls.
 */
function removeBoxAndAddNewBoxesToScene(wallPositions, wallsToChange, indexStore)
{
    for(i = 0; i < wallsToChange.length; i++)
    {
		// Remove existing wall from scene.
        ABWorld.scene.remove(wallPositions[wallsToChange[i]].wall);
        var shape    = new THREE.BoxGeometry ( squaresize, BOXHEIGHT, squaresize );			 
        var thecube  = new THREE.Mesh( shape );
        thecube.material = new THREE.MeshBasicMaterial( { map: maze_texture } );
        thecube.position.copy ( translate(indexStore[i].i, indexStore[i].j) ); 		  	// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates 
        
		// Add new wall to the scene.
		ABWorld.scene.add(thecube);
		// Set removed walls position in Grid as blank. 
		// This will make sure that A* algorithm would consider the changes in the walls.
        GRID[wallPositions[wallsToChange[i]].i][wallPositions[wallsToChange[i]].j].cellType = GRID_BLANK;        
        wallPositions[wallsToChange[i]] = new Wall(thecube, indexStore[i].i, indexStore[i].j)
		// Set new wall position in Grid as wall.
		// This will make sure that A* algorithm would consider the changes in the walls.
        GRID[indexStore[i].i][indexStore[i].j].cellType = GRID_MAZE;           
    }   
	
}

/**
 * Represents Wall object
 * @param {object} wall 
 * @param {number} i 
 * @param {number} j 
 */
function Wall(wall, i, j)
{
    this.i = i;
    this.j = j;
    this.wall = wall;
}

/**
 * Represent each node as an obect with properties to run A*
 * @param {number} i 
 * @param {number} j 
 */
function AStarNode(i, j) 
{

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

  // Cell type
  this.cellType = undefined;

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

  // Neighbors
  this.neighbors = [];

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

  // Figure out who my neighbors are
  this.addNeighbors = function(grid) 
  {
    var i = this.i;
    var j = this.j;
    
    if (i < gridsize - 2)   this.neighbors.push(grid[i + 1][j]);
    if (i > 1)          this.neighbors.push(grid[i - 1][j]);
    if (j < gridsize - 2)   this.neighbors.push(grid[i][j + 1]);
    if (j > 1)          this.neighbors.push(grid[i][j - 1]);        
  };
  
  this.resetState = function(grid)
  {
	this.f = 0;
  	this.g = 0;
  	this.h = 0;
	this.neighbors = [];
	this.previous = undefined;
  };
}

/**
 * Initialize scene
 */
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] = new AStarNode(i,j);
				GRID[i][j].cellType = 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] = new AStarNode(i,j);
				GRID[i][j].cellType = GRID_BLANK;
			}
			
	// All the neighbors
	for (i = 0; i < gridsize; i++) 
		for (j = 0; j < gridsize; j++) 
			GRID[i][j].addNeighbors(GRID);
		
   // 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].cellType = 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);
        wallPositions.push(new Wall(thecube, i, j));		
	}
	 	 
   
	// 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 path

	
	// 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 } );
	 color: 0xffc0cb
*/
	shape = new THREE.SphereGeometry( 50);
	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
	 });
 		
}
 
 
 


// --- draw moving objects -----------------------------------
/**
 * Draw enemy
 */
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  
}

/**
 * Draw agent
 */
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)
}

/**
 * Draw the optimal path between enmey and agent.
 * path is already calculated by using A* algorithm.
 */
function drawPath()
{
	for(var i=1; i < path.length - 1; i++)
	{
		var shape    = new THREE.BoxGeometry ( squaresize, 1, squaresize );			 
		var thecube  = new THREE.Mesh( shape );
		thecube.material = new THREE.MeshBasicMaterial(PATHCOLOR);
		
		thecube.position.copy ( translate(path[i].i, path[i].j) ); 		  	// translate my (i,j) grid coordinates to three.js (x,y,z) coordinates 
		ABWorld.scene.add(thecube);
		pathCube.push(thecube);
	}	
}

/**
 * Reset the path and remove it from the scene.
 */
function clearPath()
{
	for(var i=0; i < pathCube.length; i++)
	{
		ABWorld.scene.remove(pathCube[i]);
	}
	pathCube = [];
}

// --- take actions -----------------------------------
/**
 * Move logical enemy.
 */
function moveLogicalEnemy()
{ 
 // move towards agent 
 // put some randomness in so it won't get stuck with barriers 
 var i = ai;
	findNextStep();
	if(path.length > 1)
	{
		if(ai != path[path.length - 2].i || aj != path[path.length - 2].j)
		{
			ei = path[path.length - 2].i;
			ej = path[path.length - 2].j;
		}				
	}
}

/**
 * Move logical agent
 * @param {number} a 
 */
function moveLogicalAgent( a )			 
{ 
    
 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 ) ); }
	
/**
 * Handle agent movement using key board.
 * @param {*} event 
 * @returns 
 */	

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: -----------------------------------
/**
 * Determine bad step
 * @returns {bool}
 */
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;
}

/**
 * Check whether agent is blocked.
 * @returns {bool}
 */
function agentBlocked()			// agent is blocked on all sides and one of the sides has enemy, run over
{
 return ( 	occupied (ai-1,aj) 		&& 
		occupied (ai+1,aj)		&&
		occupied (  ai,aj+1)		&&
		occupied (  ai,aj-1) && 
		(isEnemy(ai-1,aj) || isEnemy(ai+1,aj) || isEnemy(ai,aj+1) || isEnemy(ai,aj-1)));		
} 

/**
 * 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
 * @param {number} a 
 */
function updateStatusBefore(a)
{
 var x 		= AB.world.getState();
 AB.msg ( " Step: " + AB.step + " &nbsp; x = (" + x.toString() + ") &nbsp; a = (" + a + ") " ); 
}

/**
 * Calculate state after agent and enemy moved.
 */
function   updateStatusAfter()	
{
 // 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 ); 
}


/**
 * Represents the new run.
 * Like main() in conventional programming.
 */
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;	
		 
};

/**
 * Get current state.
 * @returns State as array
 */
AB.world.getState = function()
{
 var x = [ ai, aj, ei, ej ];
  return ( x );  
};

/**
 * Take action
 * @param {number} a 
 */
AB.world.takeAction = function ( a )
{
  updateStatusBefore(a);			// show status line before moves 
  if( AB.step % WALLMOVETICK == 0)  // Update walls dynamically on each WALLMOVETICK interval
  {
    findWallPositionsToChange();
  }
  
  if ( ( AB.step % 2 ) === 0 )		// slow the enemy down to every nth step
    moveLogicalEnemy();

  moveLogicalAgent(a);  

  if ( badstep() )  badsteps++;
  else   			goodsteps++;
  clearPath();
  if( ( AB.step % 2 ) === 0 )
   {
	   drawPath()
   }
   drawEnemy();
   drawAgent();      
   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();
  }

};

/**
 * End run
 */
AB.world.endRun = function()
{
  musicPause(); 
  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  );
};

 /**
  * Calculate score
  * @returns {number}
  */ 
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(); }

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