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Graphics / Rendering quads show nothing if texture is ussed

« on: September 13, 2021, 06:10:38 pm »

Hi there!

My goal is to render some quads to simulate an isometric cube, let's take Minecraft icon as reference:



So, I'm loading this 32w16h texture without issues:



And creating and drawing sf::VertexArray like this in the window.isOpen() loop:

        sf::Texture grass;
        if (!grass.loadFromFile("grass.png"))
                return 0;

...
...

                window.clear();

                sf::VertexArray cube(sf::Quads);
                const sf::Vector2f position{ 100.f, 100.f };
                constexpr float size = 50.f;

                cube.append({ position - (vertex[5] * size),    {}, { 0.f,  0.f} });
                cube.append({ position,                         {}, {16.f,  0.f} });
                cube.append({ position - (vertex[3] * size),    {}, {16.f, 16.f} });
                cube.append({ position - (vertex[4] * size),    {}, {0.f,  16.f} });

                cube.append({ position - (vertex[5] * size),    {}, {16.f,  0.f} });
                cube.append({ position - (vertex[0] * size),    {}, {32.f,  0.f} });
                cube.append({ position - (vertex[1] * size),    {}, {32.f, 16.f} });
                cube.append({ position,                         {}, {16.f, 16.f} });

                cube.append({ position,                         {}, { 0.f,  0.f} });
                cube.append({ position - (vertex[1] * size),    {}, {16.f,  0.f} });
                cube.append({ position - (vertex[2] * size),    {}, {16.f, 16.f} });
                cube.append({ position - (vertex[3] * size),    {}, {0.f,  16.f} });

                window.draw(cube, &grass);
                window.display();

This results in a black screen (except for the imgui controls I've added). The vertex static array that I'm multiplying values with is defined like this:

template <auto degrees>
constexpr auto radians = degrees * std::numbers::pi_v<decltype(degrees)> / 180;

/*
    0 0 _______ 1 60
       /   y  /|
5 300 /______/ |
      |      |x| 2 120
      |  z   | /
      |______|/
4 240        3 180
*/

const static sf::Vector2f vertex[]
{
        {std::sin(radians<  0.f>), std::cos(radians<  0.f>)},
        {std::sin(radians< 60.f>), std::cos(radians< 60.f>)},
        {std::sin(radians<120.f>), std::cos(radians<120.f>)},
        {std::sin(radians<180.f>), std::cos(radians<180.f>)},
        {std::sin(radians<240.f>), std::cos(radians<240.f>)},
        {std::sin(radians<300.f>), std::cos(radians<300.f>)},
};

It just contains the vertex possitions of an exagon, nothing special here.

If instead of rendering using a texture I just render using vertex color, there's no problem displaying the cube:

                window.clear();

                sf::VertexArray cube(sf::Quads);
                const sf::Vector2f position{ 100.f, 100.f };
                constexpr float size = 50.f;

                cube.append({ position - (vertex[5] * size),    sf::Color::Red });
                cube.append({ position,                                                 sf::Color::Red });
                cube.append({ position - (vertex[3] * size),    sf::Color::Red });
                cube.append({ position - (vertex[4] * size),    sf::Color::Red });

                cube.append({ position - (vertex[5] * size),    sf::Color::Green });
                cube.append({ position - (vertex[0] * size),    sf::Color::Green });
                cube.append({ position - (vertex[1] * size),    sf::Color::Green });
                cube.append({ position,                                                 sf::Color::Green });

                cube.append({ position,                                                 sf::Color::Blue });
                cube.append({ position - (vertex[1] * size),    sf::Color::Blue });
                cube.append({ position - (vertex[2] * size),    sf::Color::Blue });
                cube.append({ position - (vertex[3] * size),    sf::Color::Blue });

                window.draw(cube, &grass);
[code=cpp]
Result:
[img]https://i.stack.imgur.com/UDdgy.png[/img]

If I don't pass the texture to the [tt]draw[/tt] function the plain colors look brighter:
[img]https://i.stack.imgur.com/uxkTz.png[/img]

Which makes me think that it might have something to do with the lack of light on the scene? I don't know, I'm pretty lost here.

Any guidance would be appreciated. Thank you very much.