How to make a grid?

[phil652]

I'm trying to make a grid for a game which will only be dots like this image without all the lines. I want to make it so its the same distance between every dots.
http://cdn2.sbnation.com/uploads/chorus_image/image/13111257/eve_online_hacking_game.0_cinema_640.0.jpg

I am using SFML 2.1

Even just an idea would help.
Thank you

[Kojay]

Something like this?

const int nofRows;
const int nofCols;
const int distance; //distance between dots
const float offset = distance/2.f;
const float height = std::sqrt(std::pow(distance,2) - std::pow(offset,2));

for (int i=0; i<nofRows; ++i){
        for (int j=0; j<nofCols; ++j){
                if (i%2==0) dot.setPosition(j*distance, i*height);
                else dot.setPosition(j*distance+offset, i*height);
        }
}

Odd rows get offset by half the distance. Gap between rows is the height of the equilateral triangles.

[phil652]

Okay, thank you for your reply, what is dot?
Do I need to set it as an image or a circle shape?

[Kojay]

That was a mere suggestion in kind of pseudo-code.

dot is whatever you want it to be. It can be a CirleShape, a Sprite, a class you write yourself with a setPosition() method. You can draw the same one multiple times; or you can have multiple and put them in a container - in which case

dot[i][j].setPosition()

is more like what you 'd have in your code.

[phil652]

Now I am able to get a dot but I can't figured out how to duplicate it.
Is there anywhere I could find a tutorial about this?

[Kojay]

Have you checked the SFML Graphic tutorials to get familiar with how everything works?

Here's the above code in a basic working example

#include <SFML/Graphics.hpp>

int main()
{
    sf::RenderWindow window(sf::VideoMode(300, 150), "Dots");
    sf::CircleShape dot(5.f);
    dot.setFillColor(sf::Color::Yellow);

        const int nofRows = 5; //number of rows
        const int nofCols = 10; //number of columns
        const int distance = 30; //distance between dots
        const float offset = distance/2.f; //offset for odd rows
        const float height = std::sqrt(std::pow(distance,2.f) - std::pow(offset,2.f)); //height of triangles

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

                window.clear();
                for (int i=0; i<nofRows; ++i){
                        for (int j=0; j<nofCols; ++j){
                                if (i%2==0) dot.setPosition(j*distance, i*height); //even rows
                                else dot.setPosition(j*distance+offset, i*height); //odd rows
                                window.draw(dot);
                        }
                }
                window.display();
        }

        return 0;
}
 

(had forgotten to take square root for correct height)
Good luck.

[phil652]

Thank you very much this is exactly what I was looking for 
If someone else read this and wondering why the code does not work. He just forgot #include <cmath> :p

Thanks again!