

 This page uses content from Wikipedia. The original article was at Snake_(video_game). The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)


Snake is a game where the player maneuvers a line which grows in length every time the snake reaches a food source.



Task
Implement a variant of the Snake game, in any interactive environment, in which a sole player attempts to eat items by running into them with the head of the snake.

Each item eaten makes the snake longer and a new item is randomly generated somewhere else on the plane.

The game ends when the snake attempts to eat himself.




 
const L = 1, R = 2, D = 4, U = 8;
var block = 24, wid = 30, hei = 20, frameR = 7, fruit, snake;
function Snake() {
    this.length = 1;
    this.alive = true;
    this.pos = createVector( 1, 1 );
    this.posArray = [];
    this.posArray.push( createVector( 1, 1 ) );
    this.dir = R;
    this.draw = function() {
        fill( 130, 190, 0 );
        var pos, i = this.posArray.length - 1, l = this.length;
        while( true ){
            pos = this.posArray[i--];
            rect( pos.x * block, pos.y * block, block, block );
            if( --l == 0 ) break;
        }
    }
    this.eat = function( frut ) {
        var b = this.pos.x == frut.x && this.pos.y == frut.y;
        if( b ) this.length++;
        return b;
    }
    this.overlap = function() {
        var len = this.posArray.length - 1;
        for( var i = len; i > len - this.length; i-- ) {
            tp = this.posArray[i];
            if( tp.x === this.pos.x && tp.y === this.pos.y ) return true;
        }
        return false;
    }
    this.update = function() {
        if( !this.alive ) return;
        switch( this.dir ) {
            case L:
                this.pos.x--; if( this.pos.x < 1 ) this.pos.x = wid - 2;
            break;
            case R:
                this.pos.x++; if( this.pos.x > wid - 2 ) this.pos.x = 1;
            break;
            case U:
                this.pos.y--; if( this.pos.y < 1 ) this.pos.y = hei - 2;
            break;
            case D:
                this.pos.y++; if( this.pos.y > hei - 2 ) this.pos.y = 1;
            break;
        }
        if( this.overlap() ) { this.alive = false; } else {
            this.posArray.push( createVector( this.pos.x, this.pos.y ) );
            if( this.posArray.length > 5000 ) { this.posArray.splice( 0, 1 ); }
        }
    }
}
function Fruit() {
    this.fruitTime = true;
    this.pos = createVector();
    this.draw = function() {
        fill( 200, 50, 20 );
        rect( this.pos.x * block, this.pos.y * block, block, block );
    }
 
    this.setFruit = function() {
        this.pos.x = floor( random( 1, wid - 1 ) );
        this.pos.y = floor( random( 1, hei - 1 ) );
        this.fruitTime = false;
    }
}
function setup() {
    createCanvas( block * wid, block * hei );
    noStroke(); frameRate( frameR );
    snake = new Snake();fruit = new Fruit();
}
function keyPressed() {
    switch( keyCode ) {
        case LEFT_ARROW: snake.dir = L; break;
        case RIGHT_ARROW: snake.dir = R; break;
        case UP_ARROW: snake.dir = U; break;
        case DOWN_ARROW: snake.dir = D;
    }
}
function draw() {
    background( color( 0, 0x22, 0 ) );
    fill( 20, 50, 120 );
    for( var i = 0; i < wid; i++ ) {
        rect( i * block, 0, block, block );
        rect( i * block, height - block, block, block );
    }
    for( var i = 1; i < hei - 1; i++ ) {
        rect( 1, i * block, block, block );
        rect( width - block, i * block, block, block );
    }
    if( fruit.fruitTime ) {
        fruit.setFruit();
        frameR += .2;
        frameRate( frameR );
    }
    fruit.draw();
    snake.update();
    if( snake.eat( fruit.pos ) ) {
        fruit.fruitTime = true;
    }
    snake.draw();
    fill( 200 );
    textStyle( BOLD ); textAlign( RIGHT ); textSize( 120 );
    text( ""+( snake.length - 1 ), 690, 440 );
    if( !snake.alive ) text( "THE END", 630, 250 );
}
 