NakedFish NakedFish - 1 month ago 8
C++ Question

How to draw on a single buffer for generative art purposes

I'm actually facing a issue I can't solve by myself, using SFML I have a single shape, and I'm moving it at each frame, and then I draw it. The problem is, SFML using two buffers, the trail won't be the same on each buffer (frame) and it will give a weird blinking effect.

I need your knowledge, should I find another way of doing it, like an array of shapes that I'll extend. Or is there a way to skip the second buffer? Making this buffer a piece of paper, and my shape the brush.

sf::CircleShape circle;
//Init the circle (radius etc)
sf::Vector2f pos(0, 500);

while(!done)
{
pos.x += 1;
circle.setPosition(pos);
window.draw(circle);
window.display();
}


May you spend a nice day.

Answer

you can achieve that by using sf::RenderTexture which acts as the back buffer (single buffer) to make your drawing and then draw it on screen via sf::RenderWindow`

#include <SFML/Graphics.hpp>

int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 600), "SFML art");
    window.setVerticalSyncEnabled(true);

    sf::RenderTexture target;
    if (!target.create(window.getSize().x, window.getSize().y))
        return -1;

    target.clear(sf::Color::White);
    target.display();

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

        if (sf::Mouse::isButtonPressed(sf::Mouse::Left))
        {
            sf::CircleShape circle(5.f, 32u);
            circle.setPosition(sf::Vector2f(sf::Mouse::getPosition(window)));
            circle.setFillColor(sf::Color::Red);
            target.draw(circle, sf::BlendNone);
            target.display();
        }

        window.clear();
        window.draw(sf::Sprite(target.getTexture()));
        window.display();
    }
}
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