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Title	Snake (No Death)
ID	4719965228761088
Created	11 years ago, 1397569144086
Updated	11 years ago, 1414610482490
Code	/** * A Khan Academy version of the classic arcade game * "Snake" / //IF YOU WANT TO TURN ON DEATHS FIND THE BLUE TEXT IN THE CODE, ONE IS NEAR TOP, OTHER NEAR BOTTOM /* Use the arrow keys to move the star around and * eat the avatars/grow the snake. / ///////////// SETTINGS ///////////// // number of {rows\|columns} var N = 20; // starting length of snake // click "Restart" if you change this var START_LENGTH = 1; // increase to slow down the game var GAME_SPEED = 3; // how many cycles to wait before letting the // user restart var GAME_OVER_TIMEOUT = 20; /* IF YOU WANT TO TURN ON DEATH BY TOUCHING WALLS CHANGE TO FALSE / var WRAP_AROUND = true; ///////////// GLOBAL VARIABLES ///////////// var apple; // the avatar to be eaten next var snake; var gameOver; // true when the game is over var gameOverTimer; // height is the canvas height var rowHeight = height / N; // keep track of arrow keypresses var keystack = []; ///////////// IMAGE VARIABLES ///////////// var star = getImage("cute/Star"); var oldspice = getImage("avatars/old-spice-man"); var mrpink = getImage("avatars/mr-pink"); var marcimus = getImage("avatars/marcimus"); var pants = getImage("avatars/mr-pants"); var squid = getImage("avatars/orange-juice-squid"); var purple = getImage("avatars/purple-pi"); var pi = getImage("avatars/piceratops-ultimate"); var leafer = getImage("avatars/leafers-ultimate"); var mrob = getImage("avatars/robot_male_3"); var frob = getImage("avatars/robot_female_3"); var leaf = getImage("avatars/leaf-green"); var sam = getImage("avatars/spunky-sam"); var winston = getImage("creatures/Winston"); var hopper1 = getImage("creatures/Hopper-Happy"); var hopper2 = getImage("creatures/Hopper-Cool"); var eb = getImage("creatures/OhNoes"); var boy = getImage("cute/CharacterBoy"); var girl = getImage("cute/CharacterCatGirl"); var bug = getImage("cute/EnemyBug"); var beet = getImage("space/beetleship"); var oct = getImage("space/octopus"); var rock = getImage("space/rocketship"); var aqua = getImage("avatars/aqualine-ultimate"); var dusk = getImage("avatars/duskpin-ultimate"); var prim = getImage("avatars/primosaur-ultimate"); var stark = getImage("avatars/starky-ultimate"); var images = [oldspice, mrpink, marcimus,pants, squid, purple, pi, leafer, mrob, frob, leaf, sam, winston, hopper1, hopper2, eb, boy, girl, bug, beet, oct, rock, aqua, dusk, prim, stark]; ///////////// UTILITY FUNCTIONS ///////////// // generate a random integer var randomInt = function(min, max) { var num = random(min, max); return floor(num); }; // a generic timer function var Timer = function(limit) { // initialize var t = limit; return { reset: function() { t = limit; }, decr: function() { if (t > 0) { t -= 1; } else { t = 0; } }, isUp: function() { return t === 0; } }; }; // record key presses var keyPressed = function() { if (!gameOver) { if (keyCode === RIGHT \|\| keyCode === LEFT \|\| keyCode === UP \|\| keyCode === DOWN) { keystack.push(keyCode); } } }; ///////////// DRAWING FUNCTIONS ///////////// var drawUnit = function(row, col, i) { var h = rowHeight; var x = col h; var y = row * h; image(images[i], x, y, h, h); }; var drawBackground = function(opacity) { fill(36, 36, 36, opacity); rect(0, 0, height, height); }; var drawGrid = function() { stroke(46, 46, 46); for (var i = 0; i < N; i += 1) { var x = i / N * height; line(x, 0, x, height); line(0, x, height, x); } }; var drawGameOverScreen = function() { drawBackground(150); var font = createFont("monospace", 20); textFont(font, 20); textSize(60); fill(49, 201, 26); text("GAME OVER", 38, 175); textSize(26); text("Score: " + snake.score(), 132, 239); if (gameOverTimer.isUp()) { textSize(16); text("Press any key to start over.", 66, 314); } }; ///////////// APPLE ///////////// var Apple = function() { this.init = function() { this.row = randomInt(0, N); this.col = randomInt(0, N); this.img = randomInt(0, images.length); }; this.positionMatch = function(row, col) { return this.row === row && this.col === col; }; this.draw = function() { stroke(69, 69, 69); strokeWeight(1); fill(20, 20, 20); var h = rowHeight; var x = (this.col + 0.5) * h; var y = (this.row + 0.5) * h; ellipse(x, y, h * 1.5, h * 1.5); drawUnit(this.row, this.col, this.img); }; this.init(); }; ///////////// SNAKE ///////////// var Snake = function() { var rowArr = []; // row index of each body part var colArr = []; // column index of each body part var imgArr = []; // index of image for each body part var direction; // current direction of snake movement var nextDirection; // direction in the next frame var score; // number of apples this snake has eaten var init = function() { // start with a brand new snake rowArr = []; colArr = []; imgArr = []; // start the snake off in the upper left corner // the last element is the head for (var i = 0; i < START_LENGTH; i += 1) { rowArr.push(0); colArr.push(i); // generate a random image for each body // segment imgArr.push(randomInt(0, images.length)); } // start snake moving to the right direction = RIGHT; score = 0; }; // delta (change increment) for the snake's movement var getDelta = function(direction) { var row = 0; var col = 0; if (direction === DOWN) { row = 1; } else if (direction === UP) { row = -1; } else if (direction === LEFT) { col = -1; } else if (direction === RIGHT) { col = 1; } return {row: row, col: col}; }; // set index so that it's within the bounds [0, N-1] var makeInBounds = function(index, wrapAround) { if (!wrapAround) { if (index === N \|\| index === -1) { gameOver = true; return; } } else { if (index === N) { index = 0; } else if (index === -1) { index = N; } } return index; }; // true if a snake segment exists at (row, col) var segmentAt = function(row, col) { var len = rowArr.length; for (var i = 0; i < len; i += 1) { if (row === rowArr[i] && col === colArr[i]) { return true; } } return false; }; var changeDirection = function() { var dir = direction; // by default the next direction will be the // same as the current direction nextDirection = dir; if (keystack.length) { var key = keystack.pop(); if (dir === RIGHT \|\| dir === LEFT) { if (key === UP \|\| key === DOWN) { nextDirection = key; } } else if (dir === UP \|\| dir === DOWN) { if (key === RIGHT \|\| key === LEFT) { nextDirection = key; } } } }; this.move = function(apple) { // don't move unless the frame number is a // multiple of GAME_SPEED if (frameCount % GAME_SPEED !== 0) { return; } changeDirection(); // get snake "head" var row = rowArr[rowArr.length-1]; var col = colArr[colArr.length-1]; // get next movement direction = nextDirection; var delta = getDelta(direction); var rowNext = row + delta.row; var colNext = col + delta.col; rowNext = makeInBounds(rowNext, WRAP_AROUND); colNext = makeInBounds(colNext, WRAP_AROUND); /** IF YOU WANT TO TURN ON DEATH BY SNAKE COLLIDING WITH ITSELF CHANGE TO TRUE / if (segmentAt(rowNext, colNext)) { gameOver = false; } // exit before advancing the snake if (gameOver) { return; } // if the next movement lands on the apple if (apple.positionMatch(rowNext, colNext)) { // add it to the snake tail imgArr.unshift(apple.img); apple.init(); score++; } else { // otherwise, "move" the snake by removing // the tail segment rowArr.shift(); colArr.shift(); } // "move" the snake by adding a new segment to // the head (note that imgArr is not changed) rowArr.push(rowNext); colArr.push(colNext); }; this.draw = function() { fill(255, 64, 64); var h = rowHeight; var len = rowArr.length; for (var i = 0; i < len; i += 1) { if (i === len - 1) { // draw a star for the head var x = colArr[i] h; var y = (rowArr[i] - 0.7) * h; image(star, x, y, h, h * 2); } else { // use the image for everything else drawUnit(rowArr[i], colArr[i], imgArr[i]); } } }; this.score = function() { return score; }; init(); }; ///////////// START GAME ///////////// var startGame = function() { snake = new Snake(); apple = new Apple(); gameOverTimer = Timer(GAME_OVER_TIMEOUT); gameOver = false; }; // begin with a new game startGame(); ///////////// MAIN GAME LOOP ///////////// var draw = function() { drawBackground(255); drawGrid(); snake.draw(); apple.draw(); if (!gameOver) { snake.move(apple); } else { drawGameOverScreen(); // don't let the user restart the game // until the timer is up if (keyIsPressed && gameOverTimer.isUp()) { startGame(); } else { gameOverTimer.decr(); } } }; //Based off of https://www.khanacademy.org/cs/snake/955120070
Folds
Fork	false
Key	ag5zfmtoYW4tYWNhZGVteXIXCxIKU2NyYXRjaHBhZBiAgMDWiJmxCAw
Votes	209
Spin-Offs	52
Type	PJS
Width	400
Height	400
User Flagged	false
Origin Scratchpad	null
Hidden From Hotlist	false
Restricted Posting	false
By Child	false
Author Nick	Cameron J
Author Name	kaid_67647990569365920510517
Author ID	kaid_67647990569365920510517
Author Profile Access	PUBLIC

Archive Data

Added	10 months ago, 1739366845899
Updated	10 months ago, 1739366854098
Source Deleted	unknown