Sketch to Polygon - Siv3D/Reference-JP GitHub Wiki

# include <Siv3D.hpp>

void Main()
{
    Image image(Window::Size(), Color(0, 0));

    DynamicTexture texture(image);

    Array<Polygon> polygons;

    while (System::Update())
    {
        if (Input::MouseL.pressed)
        {
            const Point from = Input::MouseL.clicked ? Mouse::Pos() : Mouse::PreviousPos();

            Line(from, Mouse::Pos()).overwrite(image, 6, Palette::Green);

            texture.fill(image);
        }
        else if (Input::MouseL.released)
        {
            const Polygon polygon = Imaging::FindExternalContour(image, true);

            if (polygon.num_vertices > 0)
            {
                const Polygon simplePolygon = polygon.simplified(2.0);

                polygons.push_back(simplePolygon);

                image.fill(Color(0, 0));

                texture.fill(image);
            }
        }

        for (const auto& polygon : polygons)
        {
            polygon.draw();

            polygon.drawWireframe(1.0, Palette::Blue);
        }

        texture.draw();
    }
}