SFML Tile culling and drawing using sf::VertexArray

main.cpp

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

int main() {

    sf::RenderWindow window(sf::VideoMode(640, 480), "Tile Culling");

    // our view
    sf::View camera;
    camera.setSize(320,240);
    camera.setCenter(160, 120);

    int mapWidth = 20;
    int mapHeight = 15;

    // a silly little map
    std::vector<int> intMap {
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
    };


    while (window.isOpen()){

        sf::Event event;

        while (window.pollEvent(event)){
            if (event.type == sf::Event::Closed){
                window.close();
            }
        }

        window.clear(sf::Color::Magenta);

        window.setView(camera);

        int tileSize = 32;

        // get our starting x/y in tile coordinates
        int startX = (int)floorf(camera.getViewport().left / tileSize);
        int startY = (int)floorf(camera.getViewport().top / tileSize);

        // The +1 is a buffer. I like having a little bit of a buffer.
        int across = (int)camera.getSize().x / tileSize + 1;
        int down = (int)camera.getSize().y / tileSize + 1;

        sf::VertexArray tileVertexArray(sf::Quads, 4);
        tileVertexArray.resize(4 * across * down);

        int totalTilesDrawn = 0;

        int vertexPosition = 0;
        for (int x = startX; x < startX + across; ++x){
            for (int y = startY; y < startY + down; ++y){
                // convert 2D coordinate to 1D array index
                int index = y * mapWidth + x;

                int tileHere = intMap[index];

                
                // Set the four corners that make up the quad for this tile:
                tileVertexArray[vertexPosition].position = sf::Vector2f(x * tileSize, y * tileSize);  // top left corner
                tileVertexArray[vertexPosition + 1].position = sf::Vector2f(x * tileSize + tileSize, y * tileSize); // top right corner
                tileVertexArray[vertexPosition + 2].position = sf::Vector2f(x * tileSize + tileSize, y * tileSize + tileSize); // bottom right corner
                tileVertexArray[vertexPosition + 3].position = sf::Vector2f(x * tileSize, y * tileSize + tileSize); // bottom left corner

                // I'm just going to draw colors for this example, but the textured version
                // is very similar.
                if (tileHere == 0){
                    tileVertexArray[vertexPosition].color = sf::Color::White;
                    tileVertexArray[vertexPosition + 1].color = sf::Color::White;
                    tileVertexArray[vertexPosition + 2].color = sf::Color::White;
                    tileVertexArray[vertexPosition + 3].color = sf::Color::White;
                }
                else if (tileHere == 1){
                    tileVertexArray[vertexPosition].color = sf::Color::Black;
                    tileVertexArray[vertexPosition + 1].color = sf::Color::Black;
                    tileVertexArray[vertexPosition + 2].color = sf::Color::Black;
                    tileVertexArray[vertexPosition + 3].color = sf::Color::Black;
                }

                ++totalTilesDrawn;
                vertexPosition += 4;
            }
        }

        // we've figured out the tiles, now draw once
        window.draw(tileVertexArray);

        window.setView(window.getDefaultView());

        window.display();
    }

    return 0;
}