Check if a point is in a rotated rectangle (C#)

Question

I have a program in C# (Windows Forms) which draws some rectangles on a picturebox. They can be drawn at an angle too (rotated).

I know each of the rectangles\' star

Answer 1

Edit: After looking back, I'm using MonoGame and the OP is using Windows Forms. The following is for MonoGame.

I've been messing this for a while now and have found a couple answers, just none of them actually worked. Here is a C# function that does exactly as OP describes, if not for OP then other people Googling like I was.

It was a headache to figure this out. A lot of the typical guesswork.

    bool PointIsInRotatedRectangle(Vector2 P, Rectangle rect, float rotation)
    {
        Matrix rotMat = Matrix.CreateRotationZ(-rotation);
        Vector2 Localpoint = P - (rect.Location).ToVector2();
        Localpoint = Vector2.Transform(Localpoint, rotMat);
        Localpoint += (rect.Location).ToVector2();

        if (rect.Contains(Localpoint)) { return true; }
        return false;
    }

And here it is in a single line of code. Probably faster to use.

    bool PointIsInRotatedRectangle(Vector2 P, Rectangle rect, float rotation)
    {
        return rect.Contains(Vector2.Transform(P - (rect.Location).ToVector2(), Matrix.CreateRotationZ(-rotation)) + (rect.Location).ToVector2());
    }