SFML：如何更改tilemap中的图块？

Question

我创建了一个类来加载效果很好的tilemap。在我的应用程序中，我想在单击时更改此地图中的图块，我做了一个程序，该程序可以知道单击了哪个图块，但找不到在tilemap中更改图块的正确方法。

TileMap.h：

#ifndef TILEMAP_H
#define TILEMAP_H

#include <SFML/Graphics.hpp>
#include <iostream>
#include <cstring>

class TileMap : public sf::Drawable, public sf::Transformable
{
    public:
        void createTileMap(std::string path, int tilesize, int tiles);
        void changeTile(int f, char c);
        virtual void draw(sf::RenderTarget &target, sf::RenderStates states) const;

    private:
        int index = 0;
        char blocks[3364];
        sf::Texture tileset;
        sf::VertexArray vertices;
};

#endif

TileMap.cpp：

void TileMap::createTileMap(std::string path, int tilesize, int tiles)
{
    //load the texture of tiles.
    if(!tileset.loadFromFile(path)) std::cout << "Unable to open map" << std::endl;

    vertices.setPrimitiveType(sf::Quads);
    vertices.resize(tiles * tiles * 4);

    for(int i = 0; i < tiles; ++i)
    {
        for(int j = 0; j < tiles; ++j)
        {
            sf::Vertex* quad = &vertices[(i + j * tiles) * 4];
            quad[0].position = sf::Vector2f(j * tilesize, i * tilesize);
            quad[1].position = sf::Vector2f(j * tilesize + tilesize, i * tilesize);
            quad[2].position = sf::Vector2f(j * tilesize + tilesize, i * tilesize + tilesize);
            quad[3].position = sf::Vector2f(j * tilesize, i * tilesize + tilesize);

            if(blocks[index] == 'G') ///GRASS
            {
                quad[0].texCoords = sf::Vector2f(0, 0);
                quad[1].texCoords = sf::Vector2f(50, 0);
                quad[2].texCoords = sf::Vector2f(50, 50);
                quad[3].texCoords = sf::Vector2f(0, 50);
            }
            index++;

void TileMap::draw(sf::RenderTarget& target, sf::RenderStates states) const
{
    states.transform *= getTransform();
    states.texture = &tileset;
    target.draw(vertices, states);
}
void TileMap::changeTile(int f, char c)
{   //this function is supposed to change a tile
    blocks[f] = c;
}

我该怎么办？