绘图 tetrominos（俄罗斯方块）

Question

我在创建/绘制 tetrominos（俄罗斯方块）时遇到问题，我在 C++ 中使用 SFML 有哪些选择？

我尝试使用 switch 语句将它们绘制为凸形并给它们编号，但由于 L 和 J 形状是凹形的，所以这不起作用。

 ConvexShape blocks;
    blocks.setTexture(&tile);

             // block generation and shape
    default_random_engine randomGenerator(time(0));
    uniform_int_distribution<int> blocktype(0,6);
    int n = blocktype(randomGenerator);
    switch (n)
    {
        case (0): blocks.setPointCount(4);
                  blocks.setPoint(0,Vector2f(0.0f,0.0f));
                  blocks.setPoint(1,Vector2f(18.0f,0.0f));
                  blocks.setPoint(2,Vector2f(18.0f,72.0f));
                  blocks.setPoint(3,Vector2f(0.0f,72.0f));
                  break;
        case (1): blocks.setPointCount(4);
                  blocks.setPoint(0,Vector2f(0.0f,0.0f));
                  blocks.setPoint(1,Vector2f(36.0f,0.0f));
                  blocks.setPoint(2,Vector2f(36.0f,36.0f));
                  blocks.setPoint(3,Vector2f(0.0f,36.0f));
                  break;
        case (2): blocks.setPointCount(8);
                  blocks.setPoint(0,Vector2f(0.0f,0.0f));
                  blocks.setPoint(1,Vector2f(18.0f,0.0f));
                  blocks.setPoint(2,Vector2f(18.0f,18.0f));
                  blocks.setPoint(3,Vector2f(36.0f,18.0f));
                  blocks.setPoint(4,Vector2f(36.0f,36.0f));
                  blocks.setPoint(5,Vector2f(18.0f,36.0f));
                  blocks.setPoint(6,Vector2f(18.0f,54.0f));
                  blocks.setPoint(7,Vector2f(0.0f,54.0f));
                  break;
        case (3): blocks.setPointCount(8);
                  blocks.setPoint(0,Vector2f(0.0f,0.0f));
                  blocks.setPoint(1,Vector2f(18.0f,0.0f));
                  blocks.setPoint(2,Vector2f(18.0f,18.0f));
                  blocks.setPoint(3,Vector2f(36.0f,18.0f));
                  blocks.setPoint(4,Vector2f(36.0f,54.0f));
                  blocks.setPoint(5,Vector2f(18.0f,54.0f));
                  blocks.setPoint(6,Vector2f(18.0f,36.0f));
                  blocks.setPoint(7,Vector2f(0.0f,36.0f));
                  break;
        case (4): blocks.setPointCount(8);
                  blocks.setPoint(0,Vector2f(0.0f,18.0f));
                  blocks.setPoint(1,Vector2f(18.0f,18.0f));
                  blocks.setPoint(2,Vector2f(18.0f,0.0f));
                  blocks.setPoint(3,Vector2f(36.0f,0.0f));
                  blocks.setPoint(4,Vector2f(36.0f,36.0f));
                  blocks.setPoint(5,Vector2f(18.0f,36.0f));
                  blocks.setPoint(6,Vector2f(18.0f,54.0f));
                  blocks.setPoint(7,Vector2f(0.0f,54.0f));
                  break;
        case (5): blocks.setPointCount(6);
                  blocks.setPoint(0,Vector2f(0.0f,54.0f));
                  blocks.setPoint(1,Vector2f(0.0f,0.0f));
                  blocks.setPoint(2,Vector2f(18.0f,0.0f));
                  blocks.setPoint(3,Vector2f(18.0f,40.0f));
                  blocks.setPoint(4,Vector2f(36.0f,36.0f));
                  blocks.setPoint(5,Vector2f(36.0f,54.0f));
                  break;
        case (6): blocks.setPointCount(6);
                  blocks.setPoint(0,Vector2f(0.0f,0.0f));
                  blocks.setPoint(1,Vector2f(54.0f,0.0f));
                  blocks.setPoint(2,Vector2f(54.0f,18.0f));
                  blocks.setPoint(3,Vector2f(36.0f,18.0f));
                  blocks.setPoint(4,Vector2f(36.0f,36.0f));
                  blocks.setPoint(5,Vector2f(18.0f,36.0f));
                  break;
    }

The L n J shape appear like this.

Answer 1

首先，在使用诸如 SFML 之类的库时，请务必记住，该库可能会为您提供方便的快捷方式（例如 sf::CircleShape 或 sf::RectangleShape），但您不一定非要使用它们，尤其是当它向您展示更灵活的东西时，例如sf::VertexArray。

接下来，您还必须记住，从基本原语构建四联体的方法不止一种。

这里最明显的一种是使用三角形或四边形。让我们使用四边形构建 T 形：

sf::VertexArray quads(sf::Quads);

// Left piece
quads.append({{0, 0}, sf::Color::White});
quads.append({{95, 0}, sf::Color::Red});
quads.append({{95, 95}, sf::Color::Green});
quads.append({{0, 95}, sf::Color::Blue});

// Center piece
quads.append({{100, 0}, sf::Color::White});
quads.append({{195, 0}, sf::Color::Red});
quads.append({{195, 95}, sf::Color::Green});
quads.append({{100, 95}, sf::Color::Blue});

// Right piece
quads.append({{200, 0}, sf::Color::White});
quads.append({{295, 0}, sf::Color::Red});
quads.append({{295, 95}, sf::Color::Green});
quads.append({{200, 95}, sf::Color::Blue});

// Bottom piece
quads.append({{100, 100}, sf::Color::White});
quads.append({{195, 100}, sf::Color::Red});
quads.append({{195, 195}, sf::Color::Green});
quads.append({{100, 195}, sf::Color::Blue});

请注意，移动平台不支持sf::Quads，您必须定义三角形而不是四边形。我还故意将四边形的长度/宽度缩短了 5 以留下可见的间隙。

可能更优雅（和高效）的解决方案是使用三角扇。由于 T tetromino 是凹形，因此您必须为您的风扇选择正确的起点，即使形状凹入的点之一。在其他情况下，您可能必须专门为此创建一个新的（不可见的）点，例如在形状内部。

sf::VertexArray triangleFan(sf::TriangleFan);

// Starting point is the bottom left corner of the center piece
triangleFan.append({{100, 100}, sf::Color::White});
triangleFan.append({{0, 100}, sf::Color::Red});
triangleFan.append({{0, 0}, sf::Color::Green});
triangleFan.append({{300, 0}, sf::Color::Blue});
triangleFan.append({{300, 100}, sf::Color::Magenta});
// The next point creates an invisible triangle just to move to the center piece
triangleFan.append({{200, 100}, sf::Color::Black});
triangleFan.append({{200, 200}, sf::Color::Cyan});
triangleFan.append({{100, 200}, sf::Color::Yellow});

分别用{50, 50} 或{50, 350} 的平移绘制这两个形状会在屏幕上产生两个巨大的四联体：

对于您的情况，您当然必须适当地缩放它们。

如果您仍有问题或想要编译、运行和使用某些东西，我已在 GitHub 上上传了 short example。