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| 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.
assistant
(formerly Perl 6)

**Works with**: Rakudo version 2016.08

This is a variation of a demo script included in the examples folder for the Raku SDL2::Raw library bindings.

```
use SDL2::Raw;
use Cairo;

constant W = 1280;
constant H = 960;

constant FIELDW = W div 32;
constant FIELDH = H div 32;

SDL_Init(VIDEO);

my $window = SDL_CreateWindow(
    'Snake',
    SDL_WINDOWPOS_CENTERED_MASK,
    SDL_WINDOWPOS_CENTERED_MASK,
    W, H,
    OPENGL
);

my $render = SDL_CreateRenderer($window, -1, ACCELERATED +| PRESENTVSYNC);

my $snake_image = Cairo::Image.record(
    -> $_ {
        .save;
        .rectangle: 0, 0, 64, 64;
        .clip;
        .rgb: 0, 1, 0;
        .rectangle: 0, 0, 64, 64;
        .fill :preserve;
        .rgb: 0, 0, 0;
        .stroke;
        .restore;

        .save;
        .translate: 64, 0;
        .rectangle: 0, 0, 64, 64;
        .clip;
        .rgb: 1, 0, 0;
        .arc: 32, 32, 30, 0, 2 * pi;
        .fill :preserve;
        .rgb: 0, 0, 0;
        .stroke;
        .restore;
    }, 128, 128, Cairo::FORMAT_ARGB32);

my $snake_texture = SDL_CreateTexture(
    $render,
    %PIXELFORMAT<ARGB8888>,
    STATIC,
    128,
    128
);

SDL_UpdateTexture(
    $snake_texture,
    SDL_Rect.new(
        :x(0),
        :y(0),
        :w(128),
        :h(128)
    ),
    $snake_image.data,
    $snake_image.stride // 128 * 4
);

SDL_SetTextureBlendMode($snake_texture, 1);

SDL_SetRenderDrawBlendMode($render, 1);

my $snakepiece_srcrect = SDL_Rect.new(:w(64), :h(64));
my $nompiece_srcrect   = SDL_Rect.new(:w(64), :h(64), :x(64));

my $event = SDL_Event.new;

enum GAME_KEYS (
    K_UP    => 82,
    K_DOWN  => 81,
    K_LEFT  => 80,
    K_RIGHT => 79,
);

my Complex @snakepieces = 10+10i;
my Complex @noms;
my Complex $snakedir = 1+0i;
my $nomspawn   = 0;
my $snakespeed = 0.1;
my $snakestep  = 0;
my $nom        = 4;

my $last_frame_start = now;
main: loop {
    my $start = now;
    my $dt = $start - $last_frame_start // 0.00001;
    while SDL_PollEvent($event) {
        my $casted_event = SDL_CastEvent($event);
        given $casted_event {
            when *.type == QUIT    { last main }
            when *.type == KEYDOWN {
                if GAME_KEYS(.scancode) -> $comm {
                    given $comm {
                        when 'K_LEFT'  { $snakedir = -1+0i unless $snakedir ==  1+0i }
                        when 'K_RIGHT' { $snakedir =  1+0i unless $snakedir == -1+0i }
                        when 'K_UP'    { $snakedir =  0-1i unless $snakedir ==  0+1i }
                        when 'K_DOWN'  { $snakedir =  0+1i unless $snakedir ==  0-1i }
                    }
                }
            }
        }
    }

    if ($nomspawn -= $dt) < 0 {
        $nomspawn += 1;
        @noms.push: (^FIELDW).pick + (^FIELDH).pick * i unless @noms > 3;
        @noms.pop if @noms[*-1] == any(@snakepieces);
    }

    if ($snakestep -= $dt) < 0 {
        $snakestep += $snakespeed;

        @snakepieces.unshift: do given @snakepieces[0] {
            ($_.re + $snakedir.re) % FIELDW
            + (($_.im + $snakedir.im) % FIELDH) * i
        }

        if @snakepieces[2..*].first( * == @snakepieces[0], :k ) -> $idx {
            @snakepieces = @snakepieces[0..($idx + 1)];
        }

        @noms .= grep(
            { $^piece == @snakepieces[0] ?? ($nom += 1) && False !! True }
        );

        if $nom == 0 {
            @snakepieces.pop;
        } else {
            $nom = $nom - 1;
        }
    }

    for @snakepieces {
        SDL_SetTextureColorMod(
            $snake_texture,
            255,
            (cos((++$) / 2) * 100 + 155).round,
            255
        );

        SDL_RenderCopy(
            $render,
            $snake_texture,
            $snakepiece_srcrect,
            SDL_Rect.new(.re * 32, .im * 32, 32, 32)
        );
    }

    SDL_SetTextureColorMod($snake_texture, 255, 255, 255);

    for @noms {
        SDL_RenderCopy(
            $render,
            $snake_texture,
            $nompiece_srcrect,
            SDL_Rect.new(.re * 32, .im * 32, 32, 32)
        )
    }

    SDL_RenderPresent($render);
    SDL_SetRenderDrawColor($render, 0, 0, 0, 0);
    SDL_RenderClear($render);

    $last_frame_start = $start;
    sleep(1 / 50);
}

SDL_Quit();

```