snake game with sfml

#include <SFML/Graphics.hpp>
#include <iostream>
#include <stdlib.h>
#include <ctime>
#include <vector>
#include <sstream>
#include <math.h>
/*
head following direction,*/
enum Direction {UP, DOWN ,PLACE_HOLDER, LEFT , RIGHT};
Direction dir=LEFT;
Direction prevDir=DOWN;
bool gameOver = false;
float tileSize = 40.0;
sf::Vector2i screenSize(20,20);
std::vector <std::vector <float>> tailPos (20,std::vector<float>(20));
sf::Vector2i headPosition((screenSize.x/2),(screenSize.y/2));
sf::Vector2i fruitPosition;
int tailLenght = 0;

bool AreSame(double a, double b)
{
    return fabs(a - b) < 0.001;
}

void setup(float &gameSpeed)
{
    gameSpeed=0.35;
    tailLenght=0;
    headPosition.x=screenSize.x/2;
    headPosition.y=screenSize.y/2;
        for(int i = 0 ; i< screenSize.x; i++)
    {

        for(int k = 0 ; k< screenSize.y; k++)
        {



                tailPos[i][k]=0;


        }
    }
    fruitPosition.x= rand()%screenSize.x;
    fruitPosition.y= rand()%screenSize.y;
    gameOver = false;


}

void logic(float &gameSpeed)
{




    if(sf::Keyboard::isKeyPressed(sf::Keyboard::W))
    {

        dir=UP;

    }
    if(sf::Keyboard::isKeyPressed(sf::Keyboard::S))
    {
        dir=DOWN;

    }
    if(sf::Keyboard::isKeyPressed(sf::Keyboard::D))
    {
        dir= RIGHT;

    }

    if(sf::Keyboard::isKeyPressed(sf::Keyboard::A))
    {

        dir=LEFT;

    }


    if(headPosition.x == fruitPosition.x && headPosition.y == fruitPosition.y)
    {
        tailLenght++;
        gameSpeed-=(0.04*gameSpeed);
        fruitPosition.x= rand()%screenSize.x;
        fruitPosition.y= rand()%screenSize.y;

        while((tailPos[fruitPosition.x][fruitPosition.y]!=0))
        {
            fruitPosition.x= rand()%screenSize.x;
            fruitPosition.y= rand()%screenSize.y;

        }
    }
    if(headPosition.x<0||headPosition.x>19||headPosition.y<0||headPosition.y>19||(tailPos[headPosition.x][headPosition.y]>=1))
    {

        gameOver=true;


    }



}


void update(sf::Sprite &head)
{



    for(int i = 0 ; i< screenSize.x; i++)
    {

        for(int k = 0 ; k< screenSize.y; k++)
        {

            if(tailPos[i][k]>=1)
            {

                tailPos[i][k]--;

            }
        }
    }

    switch (dir){
        case UP:
        case DOWN:
    tailPos[headPosition.x][headPosition.y]=tailLenght+0.1;
        break;
        case LEFT :
        case RIGHT:
     tailPos[headPosition.x][headPosition.y]=tailLenght+0.2;

    }
    if(std::abs(prevDir-dir)==1){


        dir = prevDir;

    }
    switch (dir) {
    case UP:
         head.setTextureRect(sf::IntRect(0,0,40,40));
        headPosition.y--;
        break;
    case DOWN:
         head.setTextureRect(sf::IntRect(40,0,40,40));
        headPosition.y++;
        break;
    case LEFT:
         head.setTextureRect(sf::IntRect(80,0,40,40));
        headPosition.x--;
        break;
    case RIGHT:
        head.setTextureRect(sf::IntRect(120,0,40,40));
        headPosition.x++;
        break;




    }
prevDir=dir;


//std::cout<<headPosition.x<<" "<<headPosition.y<<std::endl;

}



void draw (sf::RenderWindow &window,sf::Sprite &head,sf::Sprite &tail,sf::Sprite &fruit,sf::Text text)
{


    for(int i = 0 ; i< screenSize.x; i++)
    {

        for(int k = 0 ; k< screenSize.y; k++)
        {



            if(i == headPosition.x && k == headPosition.y)
            {


                head.setPosition(headPosition.x*tileSize,headPosition.y*tileSize);

                window.draw(head);

            }
            if(i == fruitPosition.x && k == fruitPosition.y)
            {
                fruit.setPosition(fruitPosition.x*tileSize,fruitPosition.y*tileSize);
                window.draw(fruit);

            }

            if(tailPos[i][k]>=1)
            {
                float shit = tailPos[i][k]-floor(tailPos[i][k]);

                if(AreSame(shit,0.1)){
                    tail.setTextureRect(sf::IntRect(0,0,40,40));

                }else {

                 tail.setTextureRect(sf::IntRect(40,0,40,40));
                }
                tail.setPosition(i*tileSize,k*tileSize);
                window.draw(tail);

            }




        }

    }

//the prompt that appears
    if(gameOver==true)
    {
        std::string yel;
        std::stringstream sstream;
        sstream<<tailLenght;
        yel=sstream.str();
        text.setColor(sf::Color::Black);
        text.setPosition(200,300);
        text.setString("game over your score is :" +yel+"\n press Escape to exit \n press R to restart");
        window.draw(text);


    }


}




int main()
{
    srand(time(0));
    sf::Clock clock;
    float elapsedTime;
    float gameSpeed=0.35;
    sf::RenderWindow Window;
    Window.create(sf::VideoMode(800,800),"nigra",sf::Style::None);
    sf::Font font;
    font.loadFromFile("DejaVuSansMono.ttf");
    sf::Text text;
    text.setFont(font);


    sf::Texture textureGrass;
    textureGrass.loadFromFile("Grass.png");
    sf::Sprite Grass(textureGrass);

    sf::Texture textureHead;
    textureHead.loadFromFile("snakeHead.png");
    sf::Sprite Head(textureHead);

    sf::Texture textureTail;
    textureTail.loadFromFile("tail.png");
    sf::Sprite Tail(textureTail);

    sf::Texture textureFruit;
    textureFruit.loadFromFile("fruit.png");
    sf::Sprite Fruit(textureFruit);
    setup(gameSpeed);
    sf::Event event;
    while(Window.isOpen())
    {



        Window.draw(Grass);
//the code that makes the prompt appear
  if(gameOver){

        while(Window.waitEvent(event)){

                if(event.key.code==sf::Keyboard::Escape){
                    Window.close();

                }
                if(event.key.code==sf::Keyboard::R){
                    setup(gameSpeed);

                    break;
                }

            }
        }
//-----------------------
        std::cout<<gameSpeed<<std::endl;

        logic(gameSpeed);
        elapsedTime= clock.getElapsedTime().asSeconds();

        if(elapsedTime>=gameSpeed)
        {
            update(Head);

            clock.restart();
            elapsedTime=0;

        }



        draw(Window,Head,Tail,Fruit,text);

        Window.display();







        Window.clear();





    }



}