// Cloned by Minhui Chen on 25 Nov 2020 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 = 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: -------------------------------------------------------
//minhui chen: change to 2D
const show3d = true; // Switch between 3d and 2d view (both using Three.js)
//minhui chen: change the texture for wall maze, agent and enemy
const TEXTURE_WALL = '/uploads/minhui96/wall.jpg' ;
const TEXTURE_MAZE = '/uploads/minhui96/maze.jpg' ;
const TEXTURE_AGENT = '/uploads/minhui96/agent.jpg' ;
const TEXTURE_ENEMY = '/uploads/minhui96/enemy.png' ;
// image source:
// 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
//minhui chen: change teh gridsiez 20 to 50
const gridsize = 50; // number of squares along side of world
//minhui chen: change the desity of maze divided by 3
const NOBOXES = Math.trunc ( (gridsize * gridsize) / 3 );
// density of maze - number of internal boxes
// (bug) use trunc or can get a non-integer
const squaresize = 100; // size of square in pixels
// 5000
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
//50
//minhui chen: create a new array occ about whether squares are occupied
var occ = new Array(gridsize);
var GRID = new Array(gridsize); // 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;
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
//********* notice*************
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 ( occ[i][j] == GRID_WALL ) return true; // fixed objects
if ( occ[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 and occ as 2D array, grid will store the f g h neighbor values
// occ store whether the square are occupied
//i<50
for ( i = 0; i < gridsize ; i++ )
GRID[i] = new Array(gridsize);
for ( i = 0; i < gridsize ; i++ )
occ[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 ) )
{
occ[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
occ[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);
occ[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);
}
// loop for every column and rows, make each spot as an object
for ( i = 0; i < gridsize; i++)
for ( j = 0; j < gridsize; j++)
GRID[i][j] = new Spot(i, j);
//add all the neighbors
for ( i = 0; i < gridsize; i++)
for ( j = 0; j < gridsize; j++)
GRID[i][j].addNeighbors(GRID);
// show GRID array contents
console.table(GRID);
// console.table(occ);
// 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
});
}
// --- 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 -----------------------------------
//------- A* algorithm --------------------------------------------
var pathline;
// line color for pathline
const linecolor = 0X66FF33;
function heuristic(e, a)
{
// minhui chen: calculate the distance between two vectors, the estimate cost
// euler distance
var Pos1 = new THREE.Vector3( e.i, 0, e.j);
var Pos2 = new THREE.Vector3( a.i, 0, a.j);
var distance = Pos1.distanceTo(Pos2);
return distance;
}
// Function to delete current element from the openset
function removeFromArray(arr, elt)
{
for (var i = arr.length - 1; i >= 0; i--)
if (arr[i] == elt)
arr.splice(i, 1);
}
//minhui chen: spot is an object for store the each spot information, i, j is the spot coordinate
// spot has f g h value for A* algorithm, previous is used to backwards path for find the next move position,
// obstacle value for wall and maze
// add then add all neighbors for current spot, will have 8 neighbors beacuase I allow enemy move diagonal
function Spot(i,j)
{
this.i = i;
this.j = j;
//f,g,h values
this.f = 0;
this.g = 0;
this.h = 0;
// Neighbors
this.neighbors = [];
// Where is the previouse spot for current spot
this.previous = undefined;
//Is it obstacle
if (occ[i][j] === 0){
this.obstacle = false;
// console.log('succ');
}
else{
this.obstacle = true;
// console.log('test');
}
// Figure out neighbors
this.addNeighbors = function(GRID)
{
var i = this.i;
var j = this.j;
if (i < gridsize - 1) this.neighbors.push(GRID[i + 1][j]);
if (i > 0) this.neighbors.push(GRID[i - 1][j]);
if (j < gridsize - 1) this.neighbors.push(GRID[i][j + 1]);
if (j > 0) this.neighbors.push(GRID[i][j - 1]);
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]);
}
}
//minhui chen: this function is used to detect if agent in a trap which agent will surround by maze or walls
// if agent in a trap, the enemy will try to getting agent, and find where is agent's exit
function trap(){
if(GRID[ai-1][aj].obstacle === false && GRID[ai+1][aj].obstacle === true && GRID[ai][aj-1].obstacle === true && GRID[ai][aj+1].obstacle === true){
return 0;
}
else if(GRID[ai-1][aj].obstacle === true && GRID[ai+1][aj].obstacle === false && GRID[ai][aj-1].obstacle === true && GRID[ai][aj+1].obstacle === true){
return 1;
}
else if(GRID[ai-1][aj].obstacle === true && GRID[ai+1][aj].obstacle === true && GRID[ai][aj-1].obstacle === false && GRID[ai][aj+1].obstacle === true){
return 2;
}
else if(GRID[ai-1][aj].obstacle === true && GRID[ai+1][aj].obstacle === true && GRID[ai][aj-1].obstacle === true && GRID[ai][aj+1].obstacle === false){
return 3;
}
else {
return 4;
}
}
// minhui chen:
// openset stores a list of all the spots taht have finished being evaluated
// closedset store dont need to ever revisit
// path store the roads
// enemy position and agent position
function enemyPath(){
var openSet = [],closedSet = [],path = [],start,end;
// enemy position
start = GRID[ei][ej];
// agent position
// is agent in agent, if in trap, move to agent's exits else move to agaent
switch(trap()){
case 0:
end = GRID[ai-1][aj];
break;
case 1:
end = GRID[ai+1][aj];
break;
case 2:
end = GRID[ai][aj-1];
break;
case 3:
end = GRID[ai][aj+1];
break;
case 4:
end = GRID[ai][aj];
break;
}
// console.log('agent:'+ai+','+aj);
// first node which enemy start position
openSet.push(start);
var count=0;
var findPath = false;
//---begin using A* algrothim find path----
while (openSet.length > 0)
{
// count times for find path
// count++;
// assume the lowest f one is the first
var winner = 0;
for ( i = 0; i < openSet.length; i++){
if(openSet[i].f < openSet[winner].f){
winner = i;
}
}
var current = openSet[winner];
// if find the agent then done!
if (current === end){
console.log("Done");
// find a path, change to true
findPath = true;
// clear array for next move
break;
}
// move the current to closedSet, remove from openSet
removeFromArray(openSet, current);
closedSet.push(current);
var neighbors = current.neighbors;
for ( i = 0; i < neighbors.length; i++){
var neighbor = neighbors[i];
if (!closedSet.includes(neighbor) && !neighbor.obstacle){
var tempG = current.g + heuristic(neighbor, current);
console.log('tempG' + tempG);
console.log('tempG' + tempG);
var newPath = false;
// check is this neighbor in the openSet, and is it a better path
if (openSet.includes(neighbor)){
if (tempG < neighbor.g){
neighbor.g = tempG;
newPath = true;
}
}
else {
neighbor.g = tempG;
newPath = true;
openSet.push(neighbor);
}
if (newPath){
neighbor.h = heuristic(neighbor,end);
neighbor.f = neighbor.g + neighbor.h;
console.log('FFFF:'+neighbor.f);
neighbor.previous = current;
}
}
}
// console.log('each current='+count);
// console.table(current);
}
//---- end--------------------
if( findPath === false){
console.log('fail');
return path;
}
console.log('time for find path: '+count);
console.log('enemy current: '+ei+','+ej);
// Find the path by working backwards
var temp = current;
var clearP = current;
path.push(temp);
while (temp.previous)
{
path.push(temp.previous);
temp = temp.previous;
// need to remove the previous for spot, because next will a new step, if not will cause infinite loop
clearP.previous= undefined;
clearP = temp;
}
// console.table(path);
// return path
return path;
}
// minhui chen
function drawPath(path){
// if world pathline remove it
if(pathline){
ABWorld.scene.remove(pathline);
}
// delete the last node, because last node is the previous enemy position
path.pop();
// store each node in path, and then translat to three.js coordinates
var points = [];
for(const p of path){
var v = translate(p.i,p.j);
points.push(v);
}
// draw lines
var material = new THREE.LineBasicMaterial( { color: linecolor });
var geometry = new THREE.BufferGeometry().setFromPoints( points );
pathline = new THREE.Line(geometry, material);
ABWorld.scene.add(pathline);
}
function moveLogicalEnemy()
{
// move towards agent
// put some randomness in so it won't get stuck with barriers
// i row , j column
var i, j;
var fPath = enemyPath();
//if find the path to agent, move
if(fPath.length > 0)
{
// the path last element is current position for enemy, so remove it and then move enemy
fPath.pop();
i = fPath[fPath.length - 1].i;
j = fPath[fPath.length - 1].j;
drawPath(fPath);
if( ! occupied(i,j)){
ei = i;
ej = j;
}
console.log('enemy moveto:'+ei+','+ej);
}
else{
console.log('Fail!');
return();
}
/*console.log('path');
console.table(path);*/
/*
if ( ei < ai ) i = AB.randomIntAtoB(ei, ei+1);
if ( ei == ai ) i = ei;
if ( ei > ai ) i = AB.randomIntAtoB(ei-1, ei);
if ( ej < aj ) j = AB.randomIntAtoB(ej, ej+1);
if ( ej == aj ) j = ej;
if ( ej > aj ) j = AB.randomIntAtoB(ej-1, ej);
if ( ! occupied(i,j) ) // if no obstacle then move, else just miss a turn
{
ei = i;
ej = j;
}*/
}
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 + " x = (" + x.toString() + ") 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 ( " y = (" + y.toString() + ") <br>" +
" Bad steps: " + badsteps +
" Good steps: " + goodsteps +
" 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
// top agent move
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 ( 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
}