sf::RenderTexture stencil and multisampling support

[binary1248]

SFML Tasks

• Check reported finding
• Review code
• Test implementation

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Added support for creation of a stencil attachment and multisampling to sf::RenderTexture. (#1274)

Test with this:

#include <SFML/Graphics.hpp>

int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 600, 32), "Test", sf::Style::Titlebar | sf::Style::Close);
    window.setVerticalSyncEnabled(true);

    sf::CircleShape circle(200, 9);
    circle.setFillColor(sf::Color::White);
    circle.setPosition(sf::Vector2f(200, 100));

    sf::RenderTexture renderTexture;
    renderTexture.create(800, 600, sf::ContextSettings(0, 0, 8));

    sf::Sprite sprite;
    sprite.setTexture(renderTexture.getTexture());

    bool on = true;

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if ((event.type == sf::Event::Closed) || ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Escape)))
            {
                window.close();
                break;
            }

            if ((event.type == sf::Event::KeyPressed) && (event.key.code == sf::Keyboard::Space))
            {
                on = !on;
                renderTexture.create(800, 600, sf::ContextSettings(0, 0, on ? 8 : 0));
            }
        }

        renderTexture.clear(sf::Color::Black);
        renderTexture.draw(circle);
        renderTexture.display();

        window.clear();
        window.draw(sprite);
        window.display();
    }
}

[ghost]

My review didn't even work!

[ghost]

@binary1248 I wish SFML was already pre-compiled with these changes.

[eXpl0it3r]

See the CI artifact builds

[ghost]

@eXpl0it3r Thanks. Unfortunately I see nothing. I compiled the PR example, but nothing looks to render. It's all black... I'm using MingW 32..

[ghost]

@binary1248 Thanks very much for this. It didn't work here :/. It's entirely black and when I press any key, nothing happens too.

[Foaly]

Wouldn't GL_LINEAR give smoother results? Or is the parameter irrelevant, because the textures have the same size?

[binary1248]

In the odd case the driver is stupid, this is faster and imposes no loss of quality.

[Foaly]

Hi there!
I just tested this PR and it works beautifully for me. Thanks for the work!
One thing I noticed is that when I tried to set the AA level to 16 the example stopped working for me. I checked the return code and saw that the create function failed. Looking into the code I saw that the highest AA level on my computer is 8. I think there should be a notice in sf::err when the creation failed, because of an unsupported AA level, since AA will be the most used case IMO.
I suspect this is also why the example didn't work for @hydroper.

[Foaly]

I would suggest something like this here: err() << "Impossible to create render texture (unsupported anti-aliasing level, maximum supported samples: " << samples << " )" << std::endl;

[eXpl0it3r]

It's a good point. For the RenderWindow we just fallback to the minimal setting if the config doesn't match and return the difference on sf::err(). Would this be possible here without too much effort or at least to produce an error so it's clear why something failed.

[binary1248]

I'd rather not spam the console with warnings that can be avoided with the necessary precaution. The problem with RenderWindow and this in its current state is that there is no way to check the maximum AA that is supported. It would be simple to do in both cases, but would necessitate adding static functions to both classes.

[Foaly]

Well I don't know I wouldn't consider it spam, since it informs the user why the creation of the RenderTexture failed. Also pretty much every other error case in create prints the reason to the console. But I agree its a very good idea to also add a function to get the maximum supported AA level.

[eXpl0it3r]

So you don't want to add any message @binary1248? Can you rebase it as well?

[binary1248]

Updated.