Creating Snake Game

So like another person i'm making a snake game for matlab but i'm having trouble making the snake eat more than one piece of food, and follow the head of the snake every time it makes a turn. Any help would be extremely grateful.

function draw_snake(snake,food)
plot(snake(:,1),snake(:,2), 'ws',food(1,1),food(1,2), 'rs')%creates the vectors for the food and snake and plots them 
whitebg([0 0 0])%creates black background
axis([0, 25, 0, 25])%creates the axis for gameplay
end

function checkpoint3()
global x y a b n
x =randi([10 20],1);%generates random x starting point for snake
y =randi([10 20],1);%generates random y starting point for snake 
d =randi([1,4]);% generates random direction to start in for snake 
a =randi([1 24],1);%generates random x coordinate for food
b =randi([1 24],1);%generates random y coordinate for food
snake=[x y];%defines the snake for x and y coordinates 
food=[a b];%defines food for a and b coordinates 
figure('KeyPressFcn',@my_callback);
 function my_callback(splooge,event)%callback function for movement
  switch event.Character
      case 30%says if this arrow key is pressed
          d = 1;%assign this value to that arrow key
      case 31%says if this arrow key is pressed
          d = 2;%assign this value to that arrow key
      case 29 %says if this arrow key is pressed
          d = 3;%assign this value to that arrow key
      case 28 %says if this arrow key is pressed
          d = 4;%assign this value to that arrow key
  end 
 end  
     while (snake(1)>=0 && snake(2)>=0 && snake(1)<=25 && snake(2)<=25)%runs the snake as long as its within the game board 
         draw_snake(snake,food)
switch d%calling callback function
   case 1%if this case is called on 
       snake(:,2)=snake(:,2)+1;%add value of 1 to y position
       draw_snake(snake,food)%draws the snake 
       pause(.1)
   case 2 
       snake(:,2)=snake(:,2)-1;%subtract value of 1 to y position
       draw_snake(snake,food)%draws the snake 
       pause(.1)
   case 3 
       snake(:,1)=snake(:,1)+1;%add value of 1 to x position
       draw_snake(snake,food)%draws the snake 
       pause(.1)
   case 4
       snake(:,1)=snake(:,1)-1;%subtracts value of 1 to x position
       draw_snake(snake,food)%draws the snake 
       pause(.1)
end 
      if snake(1)==food(1) && snake(2)==food(2)%if the snake and food are in the same position
          n=length(snake); %creates variable for length of snake 
          switch d 
              case 1%if up is called on 
                  snake(n,1)=food(1);%don't alter x position of new segment of snake 
                  snake(n,2)=food(2)-1;%have new segment follow from bottom 
              case 2 
                  snake(n,1)=food(1);%don't alter x position of new segment of snake 
                  snake(n,2)=food(2)+1;%have new segment follow from the top 
              case 3
                  snake(n,1)=food(1)-1;%have new segment follow from left 
                  snake(n,2)=food(2);%don't alter y position of new segment of snake 
              case 4 
                  snake(n,1)=food(1)+1;%have new segment follow from right 
                  snake(n,2)=food(2);%don't alter y position of new segment of snake 
          end
          food(1) = randi([1 25]);%creates a new x position for the food 
          food(2) = randi([1 25]);%creates a new y position for the food 
         % b = randi([1 25]);
      elseif snake(1)==0;%if snake exceeds boundaries display message box
         msgbox('YOU LOSE HAHAHA')
      elseif snake(2)==0;%if snake exceeds boundaries display message box
          msgbox('YOU LOSE HAHAHA')
      elseif snake(1)==25;%if snake exceeds boundaries display message box
          msgbox('YOU LOSE HAHAHA')
      elseif snake(2)==25;%if snake exceeds boundaries display message box
          msgbox('YOU LOSE HAHAHA')
      end 
     end 
end

[Moe Ebrahimi]

i cant play it just sais cant find varieble snake

[Walter Roberson]

In 2011 when this was posted, you would have had to put the two function into different files.

Starting from R2016b you could instead move the first function to after the second function.

Answer 1

[Andre Coelho]

I made some changes and improvements to your code. Check this:

function snake_game()
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     PRESS 'Q' TO EXIT GAME         %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
close all

%OPTIONS%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

difficulty=9;            %difficulty:  1-10
bounds=0;         %bounds? 1-yes 0-no
axis_limit= 15;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%555555555

d=0;
x =round(axis_limit/2) %starting point
y =round(axis_limit/2) %starting point
d =randi([1,4]);% generates random direction to start in for snake
a =randi([1 axis_limit-1],1);%generates random x coordinate for food
b =randi([1 axis_limit-1],1);%generates random y coordinate for food
snake(1,1:2)=[x y];%defines the snake for x and y coordinates
size_snake=1;
ate=1;   %snake ate food
ex=0;    % used to exit game
food=[a b];%defines food for a and b coordinates
draw_snake(snake,food,size_snake,axis_limit)
figure('KeyPressFcn',@my_callback);
    function my_callback(splooge,event)%callback function for movement
        switch event.Character
            case 'q'
                ex=1;
            case 30               % arrow direction
                if(d~=2)
                    d = 1;              %up d=1
                end
            case 31
                if(d~=1)
                    d = 2;              %down d=2
                end
            case 29
                if(d~=4)
                    d = 3;              %right d=3
                end
            case 28
                if(d~=3)
                    d = 4;              %left d=4
                end
        end
    end
while (ex~=1)%runs the snake as long as q is not pressed
    size_snake=size(snake);
    size_snake=size_snake(1)
    for l=size_snake+ate:-1:2
        snake(l,:)=snake(l-1,:);
    end
    switch d         %calling callback function
        case 1
            snake(1,2)=snake(1,2)+1;%add value of 1 to y position
        case 2
            snake(1,2)=snake(1,2)-1;%subtract value of 1 to y position
        case 3
            snake(1,1)=snake(1,1)+1;%add value of 1 to x position
        case 4
            snake(1,1)=snake(1,1)-1;%subtracts value of 1 to x position
    end
    draw_snake(snake,food,size_snake,axis_limit)%draws the snake

      pause(max([(105-difficulty*10)/(10*axis_limit) .001])) %diffculty makes game faster;

      if snake(1,1)==food(1) && snake(1,2)==food(2)%if the snake and food are in the same position
          ate=1;
          food(1) = randi([1 axis_limit-1]);%creates a new x position for the food
          food(2) = randi([1 axis_limit-1]);%creates a new y position for the food
      else
          ate=0;
      end
      bounds
      if bounds==1
          snake(1,:)
          if snake(1,1)==0 %if snake exceeds boundaries display message box
              msgbox('YOU LOST! HAHA')
              ex=1

          elseif snake(1,2)==0%if snake exceeds boundaries display message box
              msgbox('YOU LOST! HAHA')
              ex=1

          elseif snake(1,1)==axis_limit%if snake exceeds boundaries display message box
              msgbox('YOU LOST! HAHA')
              ex=1

          elseif snake(1,2)==axis_limit%if snake exceeds boundaries display message box
              msgbox('YOU LOST! HAHA')
              ex=1

          end
      else
          snake=snake-((snake>axis_limit).*(axis_limit+1));
          snake=snake+((snake<0).*(axis_limit+1));
      end
      if (sum(snake(:, 1) ==snake(1, 1)   & snake(:, 2) == snake(1, 2) )>1); %if snake hits itself
          msgbox('YOU LOST! HAHA')
          break

      end
  end
  close all
  end

function draw_snake(snake,food,size_snake,axis_limit)

      for p = 1:size_snake
          plot(snake(p,1),snake(p,2), 'wo')
          hold on
      end
      plot(food(1,1),food(1,2), 'rs')%creates the vectors for the food and snake and plots them
      whitebg([0 0 0])%creates black background
      axis([0, axis_limit, 0, axis_limit])%creates the axis for gameplay
      hold off
      end

[Anand Sharma]

How do we keep the scores for each game so as to compare the results afterwards?

Answer 2

[Sean de Wolski]

Did you see my suggestion in the other thread?

[Andy]

I did but I didn't really understand your approach, nor how it would be applied to the code I had already written. I'm honestly not savvy with computer code at all so I apologize for making you answer this question twice

[Sean de Wolski]

My suggestion leaves you with a matrix of zeros and integers representing the snake. The larger the integer, the further toward the tail it is. Thus if the snake eats food on an iteration, it doesn't cut off the tail, else it does.

Answer 3

[Deepika]

function snake_game()

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% PRESS 'Q' TO EXIT GAME %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

close all

%OPTIONS%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

difficulty=9; %difficulty: 1-10

bounds=0; %bounds? 1-yes 0-no

axis_limit= 15;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%555555555

d=0;

x =round(axis_limit/2) %starting point

y =round(axis_limit/2) %starting point

d =randi([1,4]);% generates random direction to start in for snake

a =randi([1 axis_limit-1],1);%generates random x coordinate for food

b =randi([1 axis_limit-1],1);%generates random y coordinate for food

snake(1,1:2)=[x y];%defines the snake for x and y coordinates

size_snake=1;

ate=1; %snake ate food

ex=0; % used to exit game

food=[a b];%defines food for a and b coordinates

draw_snake(snake,food,size_snake,axis_limit)

figure('KeyPressFcn',@my_callback);

function my_callback(splooge,event)%callback function for movement

switch event.Character

case 'q'

ex=1;

case 30 % arrow direction

if(d~=2)

d = 1; %up d=1

end

case 31

if(d~=1)

d = 2; %down d=2

end

case 29

if(d~=4)

d = 3; %right d=3

end

case 28

if(d~=3)

d = 4; %left d=4

end

end

end

while (ex~=1)%runs the snake as long as q is not pressed

size_snake=size(snake);

size_snake=size_snake(1)

for l=size_snake+ate:-1:2

snake(l,:)=snake(l-1,:);

end

switch d %calling callback function

case 1

snake(1,2)=snake(1,2)+1;%add value of 1 to y position

case 2

snake(1,2)=snake(1,2)-1;%subtract value of 1 to y position

case 3

snake(1,1)=snake(1,1)+1;%add value of 1 to x position

case 4

snake(1,1)=snake(1,1)-1;%subtracts value of 1 to x position

end

draw_snake(snake,food,size_snake,axis_limit)%draws the snake

pause(max([(105-difficulty*10)/(10*axis_limit) .001])) %diffculty makes game faster;

if snake(1,1)==food(1) && snake(1,2)==food(2)%if the snake and food are in the same position

ate=1;

food(1) = randi([1 axis_limit-1]);%creates a new x position for the food

food(2) = randi([1 axis_limit-1]);%creates a new y position for the food

else

ate=0;

end

bounds

if bounds==1

snake(1,:)

if snake(1,1)==0 %if snake exceeds boundaries display message box

msgbox('YOU LOST! HAHA')

ex=1

elseif snake(1,2)==0%if snake exceeds boundaries display message box

msgbox('YOU LOST! HAHA')

ex=1

elseif snake(1,1)==axis_limit%if snake exceeds boundaries display message box

msgbox('YOU LOST! HAHA')

ex=1

elseif snake(1,2)==axis_limit%if snake exceeds boundaries display message box

msgbox('YOU LOST! HAHA')

ex=1

end

else

snake=snake-((snake>axis_limit).*(axis_limit+1));

snake=snake+((snake<0).*(axis_limit+1));

end

if (sum(snake(:, 1) ==snake(1, 1) & snake(:, 2) == snake(1, 2) )>1); %if snake hits itself

msgbox('YOU LOST! HAHA')

break

end

end

close all

end

function draw_snake(snake,food,size_snake,axis_limit)

for p = 1:size_snake

plot(snake(p,1),snake(p,2), 'wo')

hold on

end

plot(food(1,1),food(1,2), 'rs')%creates the vectors for the food and snake and plots them

whitebg([0 0 0])%creates black background

axis([0, axis_limit, 0, axis_limit])%creates the axis for gameplay

hold off

end