game.js

// The point and size class used in this program
function Point(x, y) {
    this.x = (x)? parseFloat(x) : 0.0;
    this.y = (y)? parseFloat(y) : 0.0;
}

function Size(w, h) {
    this.w = (w)? parseFloat(w) : 0.0;
    this.h = (h)? parseFloat(h) : 0.0;
}

// Helper function for checking intersection between two rectangles
function intersect(pos1, size1, pos2, size2) {
    return (pos1.x < pos2.x + size2.w && pos1.x + size1.w > pos2.x &&
            pos1.y < pos2.y + size2.h && pos1.y + size1.h > pos2.y);
}

function createMonster(x, y) {
	var monster = svgdoc.createElementNS("http://www.w3.org/2000/svg", "use");
	svgdoc.getElementById("monsters").appendChild(monster);
	monster.setAttribute("x", x);
	monster.setAttribute("y", y);
	monster.setAttributeNS("http://www.w3.org/1999/xlink", "xlink:href", "#monster");
}

function shootBullet() {

	// Disable shooting for a short period of time
	canShoot = false;
	var timer = setTimeout("canShoot = true", SHOOT_INTERVAL);

	// Create the bullet by createing a use node
	var bullet = svgdoc.createElementNS("http://www.w3.org/2000/svg", "use");
	svgdoc.getElementById("bullets").appendChild(bullet);

    // Calculate and set the position of the bullet
	bullet.setAttribute("x", (player.position.x + (PLAYER_SIZE.w / 2)));
	bullet.setAttribute("y", (player.position.y + (PLAYER_SIZE.h / 2)));

    // Set the href of the use node to the bullet defined in the defs node
	bullet.setAttributeNS("http://www.w3.org/1999/xlink", "xlink:href", "#bullet");

    // Append the bullet to the bullet group


}

function moveBullets() {
	var bullets = svgdoc.getElementById("bullets");
	bulletCount = bullets.childNodes.length;
    for (var i = 0; i < bulletCount; i++) {
        var node = bullets.childNodes.item(i);
		var x = parseInt(node.getAttribute("x"));
        // Update the position of the bullet
		node.setAttribute("x", x + BULLET_SPEED);

        // If the bullet is not inside the screen delete it from the group
        if (x > SCREEN_SIZE.w) {
	        svgdoc.getElementById("bullets").removeChild(node);
        }

    }
}

function collisionDetection() {
    // Check whether the player collides with a monster
    var monsters = svgdoc.getElementById("monsters");
    for (var i = 0; i < monsters.childNodes.length; i++) {
        var monster = monsters.childNodes.item(i);
        // For each monster check if it overlaps with the player
        // if yes, stop the game
        var monsterPos = new Point(monster.getAttribute("x"), monster.getAttribute("y"));
        if (intersect(monsterPos, MONSTER_SIZE, player.position, PLAYER_SIZE)) {
        	alert("You are killed!");
        	gameOver();
        }
    }

    // Check whether a bullet hits a monster
    var bullets = svgdoc.getElementById("bullets");
    for (var i = 0; i < bullets.childNodes.length; i++) {
        var bullet = bullets.childNodes.item(i);

        // For each bullet check if it overlaps with any monster
        // if yes, remove both the monster and the bullet		
	    for (var i = 0; i < monsters.childNodes.length; i++) {
	        var monster = monsters.childNodes.item(i);
	        var monsterPos = new Point(monster.getAttribute("x"), monster.getAttribute("y"));
	        var bulletPos = new Point(bullet.getAttribute("x"), bullet.getAttribute("y"));
	        if (intersect(monsterPos, MONSTER_SIZE, bulletPos, BULLET_SIZE)) {
	        	score++;
	        	bullets.removeChild(bullet);
	        	monsters.removeChild(monster);
			}
        }

    }
}
function Input(){
	playerName = prompt("Enter your name ");
	if(playerName.length == 0)
		playerName = "Anonymous";
}

function gameOver() {
    clearInterval(gameInterval);
    
	var table = getHighScoreTable();
	var record = new ScoreRecord(playerName, score);//playerName, score);
	for(var i = 0 ; i < 10 ;++i){
		if(table.length == 0 || i == table.length || table[i].score < record.score   ){
			table.splice(i, 0, record);
			break;
		}
	}

	setHighScoreTable(table);
	showHighScoreTable(table);
}

// The player class used in this program
function Player() {
    this.node = svgdoc.getElementById("player");
    this.position = PLAYER_INIT_POS;
    this.motion = motionType.NONE;
    this.verticalSpeed = 0;
}

Player.prototype.isOnPlatform = function() {
    var platforms = svgdoc.getElementById("platforms");
    for (var i = 0; i < platforms.childNodes.length; i++) {
        var node = platforms.childNodes.item(i);
        if (node.nodeName != "rect") continue;

        var x = parseFloat(node.getAttribute("x"));
        var y = parseFloat(node.getAttribute("y"));
        var w = parseFloat(node.getAttribute("width"));
        var h = parseFloat(node.getAttribute("height"));

        if (((this.position.x + PLAYER_SIZE.w > x && this.position.x < x + w) ||
             ((this.position.x + PLAYER_SIZE.w) == x && this.motion == motionType.RIGHT) ||
             (this.position.x == (x + w) && this.motion == motionType.LEFT)) &&
            this.position.y + PLAYER_SIZE.h == y) return true;
    }
    if (this.position.y + PLAYER_SIZE.h == SCREEN_SIZE.h) return true;

    return false;
}

Player.prototype.collidePlatform = function(position) {
    var platforms = svgdoc.getElementById("platforms");
    for (var i = 0; i < platforms.childNodes.length; i++) {
        var node = platforms.childNodes.item(i);
        if (node.nodeName != "rect") continue;

        var x = parseFloat(node.getAttribute("x"));
        var y = parseFloat(node.getAttribute("y"));
        var w = parseFloat(node.getAttribute("width"));
        var h = parseFloat(node.getAttribute("height"));
        var pos = new Point(x, y);
        var size = new Size(w, h);

        if (intersect(position, PLAYER_SIZE, pos, size)) {
            position.x = this.position.x;
            if (intersect(position, PLAYER_SIZE, pos, size)) {
                if (this.position.y >= y + h)
                    position.y = y + h;
                else
                    position.y = y - PLAYER_SIZE.h;
                this.verticalSpeed = 0;
            }
        }
    }
}

Player.prototype.collideScreen = function(position) {
    if (position.x < 0) position.x = 0;
    if (position.x + PLAYER_SIZE.w > SCREEN_SIZE.w) position.x = SCREEN_SIZE.w - PLAYER_SIZE.w;
    if (position.y < 0) {
        position.y = 0;
        this.verticalSpeed = 0;
    }
    if (position.y + PLAYER_SIZE.h > SCREEN_SIZE.h) {
        position.y = SCREEN_SIZE.h - PLAYER_SIZE.h;
        this.verticalSpeed = 0;
    }
}


//
// Below are constants used in the game
//
var PLAYER_SIZE = new Size(40, 40);         // The size of the player
var MONSTER_SIZE = new Size(40, 40)
var SCREEN_SIZE = new Size(600, 560);       // The size of the game screen
var PLAYER_INIT_POS  = new Point(0, 0);     // The initial position of the player

var MOVE_DISPLACEMENT = 5;                  // The speed of the player in motion
var JUMP_SPEED = 15;                        // The speed of the player jumping
var VERTICAL_DISPLACEMENT = 1;              // The displacement of vertical speed

var GAME_INTERVAL = 25;                     // The time interval of running the game

var BULLET_SIZE = new Size(10, 10); // The size of a bullet
var BULLET_SPEED = 10.0;            // The speed of a bullet
                                    //  = pixels it moves each game loop
var SHOOT_INTERVAL = 200.0;         // The period when shooting is disabled

var MAX_BULLETS_ON_SCREEN = 3;

//
// Variables in the game
//
var motionType = {NONE:0, LEFT:1, RIGHT:2}; // Motion enum

var svgdoc = null;                          // SVG root document node
var player = null;                          // The player object
var gameInterval = null;                    // The interval
var zoom = 1.0;                             // The zoom level of the screen

var canShoot = true;                		// A flag indicating whether the player can shoot a bullet
var bulletCount = 0;

var playerName = "";						// The name of player
var score = 0;								// The score of game

//
// The load function for the SVG document
//
function load(evt) {
    // Set the root node to the global variable
    svgdoc = evt.target.ownerDocument;

    // Attach keyboard events
    svgdoc.documentElement.addEventListener("keydown", keydown, false);
    svgdoc.documentElement.addEventListener("keyup", keyup, false);

    // Remove text nodes in the 'platforms' group
    cleanUpGroup("platforms", true);

    // Create the player
    player = new Player();

	createMonster(100, 200);
	createMonster(200, 200);
	createMonster(0, 200);
	createMonster(100, 0);

	createMonster(0, 300);

	Input();
    // Start the game interval
    gameInterval = setInterval("gamePlay()", GAME_INTERVAL);
}


//
// This function removes all/certain nodes under a group
//
function cleanUpGroup(id, textOnly) {
    var node, next;
    var group = svgdoc.getElementById(id);
    node = group.firstChild;
    while (node != null) {
        next = node.nextSibling;
        if (!textOnly || node.nodeType == 3) // A text node
            group.removeChild(node);
        node = next;
    }
}


//
// This is the keydown handling function for the SVG document
//
function keydown(evt) {
    var keyCode = (evt.keyCode)? evt.keyCode : evt.getKeyCode();

    switch (keyCode) {
        case "N".charCodeAt(0):
            player.motion = motionType.LEFT;
            break;

        case "M".charCodeAt(0):
            player.motion = motionType.RIGHT;
            break;


        // Add your code here
        case "Z".charCodeAt(0):
        	if (player.isOnPlatform()) {
	        	player.verticalSpeed = JUMP_SPEED;
        	}
        	break;

    	case 32: // space bar
			if (canShoot == true && bulletCount < MAX_BULLETS_ON_SCREEN) {
    			shootBullet();
    		}
			break;


    }
}


//
// This is the keyup handling function for the SVG document
//
function keyup(evt) {
    // Get the key code
    var keyCode = (evt.keyCode)? evt.keyCode : evt.getKeyCode();

    switch (keyCode) {
        case "N".charCodeAt(0):
            if (player.motion == motionType.LEFT) player.motion = motionType.NONE;
            break;

        case "M".charCodeAt(0):
            if (player.motion == motionType.RIGHT) player.motion = motionType.NONE;
            break;
    }
}


//
// This function updates the position and motion of the player in the system
//
function gamePlay() {
    // Check whether the player is on a platform
    var isOnPlatform = player.isOnPlatform();

    // Update player position
    var displacement = new Point();

    // Move left or right
    if (player.motion == motionType.LEFT)
        displacement.x = -MOVE_DISPLACEMENT;
    if (player.motion == motionType.RIGHT)
        displacement.x = MOVE_DISPLACEMENT;

    // Fall
    if (!isOnPlatform && player.verticalSpeed <= 0) {
        displacement.y = -player.verticalSpeed;
        player.verticalSpeed -= VERTICAL_DISPLACEMENT;
    }

    // Jump
    if (player.verticalSpeed > 0) {
        displacement.y = -player.verticalSpeed;
        player.verticalSpeed -= VERTICAL_DISPLACEMENT;
        if (player.verticalSpeed <= 0)
            player.verticalSpeed = 0;
    }

    // Get the new position of the player
    var position = new Point();
    position.x = player.position.x + displacement.x;
    position.y = player.position.y + displacement.y;

    // Check collision with platforms and screen
    player.collidePlatform(position);
    player.collideScreen(position);

    // Set the location back to the player object (before update the screen)
    player.position = position;

    updateScreen();
}


//
// This function updates the position of the player's SVG object and
// set the appropriate translation of the game screen relative to the
// the position of the player
//
function updateScreen() {
    // Transform the player
    player.node.setAttribute("transform", "translate(" + player.position.x + "," + player.position.y + ")");

    // Calculate the scaling and translation factors
    // Add your code here
    var scale = new Point(zoom, zoom);
    var translate = new Point();

    translate.x = SCREEN_SIZE.w / 2.0 - (player.position.x - PLAYER_SIZE.w / 2) * scale.x;
    if (translate.x > 0) {
	    translate.x = 0;
    } else if (translate.x < SCREEN_SIZE.w - SCREEN_SIZE.w * scale.x) {
	    translate.x = SCREEN_SIZE.w - SCREEN_SIZE.w * scale.x;
    }

    translate.y = SCREEN_SIZE.h / 2.0 - (player.position.y - PLAYER_SIZE.h / 2) * scale.y;
    if (translate.y > 0) {
	    translate.y = 0;
    } else if (translate.y < SCREEN_SIZE.h - SCREEN_SIZE.h * scale.y) {
	    translate.y = SCREEN_SIZE.h - SCREEN_SIZE.h * scale.y;
    }

	// Update the bullet count
	bulletCount = svgdoc.getElementById("bullets").childNodes.length;
/* 	console.log(bulletCount); */


    svgdoc.getElementById("gamearea").setAttribute("transform", "translate(" + translate.x + ", " + translate.y + ") scale(" + scale.x + "," + scale.y + ")");

    moveBullets();
	collisionDetection();
	
	svgdoc.getElementById("score").firstChild.data = score;			// Update score in the SVG
}

function setZoom() {
	if (zoom == 1.0) {
		zoom++;
	} else {
		zoom--;
	}
}