Question

我有一个想要旋转的矩形。

我只有一个矩形点（鼠标位置），长度和矩形的宽度以及旋转角度。现在我需要矩形的其他三个角的位置，以便我可以使用 Graphics.DrawPolygon（）轻松绘制我的矩形。

我不知道，因为我已经数年没有数学并且需要你的帮助：D

我尝试过很多来自互联网的解决方案，但没有什么能适合我的问题。

Answer 1

以下课程可以满足您的需求。作为参考，请查看旋转的工作原理：http://en.wikipedia.org/wiki/Rotation_matrix

public class MyRectangle
{
    public double Length { get; set; }
    public double Width { get; set; }
    public double Rotation { get; private set; }
    public Coord Center { get; private set; }
    public Coord TopLeft { get; private set; }
    public Coord TopRight { get; private set; }
    public Coord BottomLeft { get; private set; }
    public Coord BottomRight { get; private set; }

    public MyRectangle(Coord origin, double length, double width)
    {
        Length = length;
        Width = width;
        Center = origin;

        BottomLeft = new Coord(Center.X - Width / 2, Center.Y - Length / 2);
        BottomRight = new Coord(Center.X + Width / 2, Center.Y - Length / 2);
        TopLeft = new Coord(Center.X - Width / 2, Center.Y + Length / 2);
        TopRight = new Coord(Center.X + Width / 2, Center.Y + Length / 2);
    }

    private void Move(Coord c)
    {

        InitCorners(new Coord((c.X - Center.X), (c.Y - Center.Y)));
        Center.X = Center.X + (c.X - Center.X);
        Center.Y = Center.Y + (c.Y - Center.Y);
    }

    private void InitCorners(Coord c)
    {
        BottomRight.X = (BottomRight.X + c.X );
        BottomRight.Y = (BottomRight.Y + c.Y);

        BottomLeft.X = (BottomLeft.X + c.X);
        BottomLeft.Y = (BottomLeft.Y + c.Y);

        TopRight.X = (TopRight.X + c.X);
        TopRight.Y = (TopRight.Y + c.Y);

        TopLeft.X = (TopLeft.X + c.X);
        TopLeft.Y = (TopLeft.Y + c.Y);
    }

    public void Rotate(double qtyRadians)
    {
        //Move center to origin
        Coord temp_orig = new Coord(Center.X, Center.Y);
        Move(new Coord(0, 0));

        BottomRight = RotatePoint(BottomRight, qtyRadians);
        TopRight = RotatePoint(TopRight, qtyRadians);
        BottomLeft = RotatePoint(BottomLeft, qtyRadians);
        TopLeft = RotatePoint(TopLeft, qtyRadians);

        //Move center back
        Move(temp_orig);
    }

    Coord RotatePoint(Coord p, double qtyRadians)
    {
        Coord temb_br = new Coord(p.X, p.Y);
        p.X = temb_br.X * Math.Cos(qtyRadians) - temb_br.Y * Math.Sin(qtyRadians);
        p.Y = temb_br.Y * Math.Cos(qtyRadians) + temb_br.X * Math.Sin(qtyRadians);

        return p;
    }
}

[DebuggerDisplay("({X},{Y})")]
public class Coord
{
    public double X { get; set; }
    public double Y { get; set; }
    public Coord(double x, double y)
    {
        X = x;
        Y = y;
    }
}

旋转矩形的点位置

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