Question

我有以下Camera类：

public Vector2 Position { get; set; } = Vector2.Zero;
public float Rotation { get; set; } = 0.0f;
public float Zoom
{
    get
    {
        // Negative zoom will flip the image
        if (_zoom < 0.1f)
        {
            _zoom = 0.1f;
        }
        return _zoom;
    }
    set
    {
        _zoom = value;
        // Negative zoom will flip the image
        if (_zoom < 0.1f)
        {
            _zoom = 0.1f;
        }
    }
}

public Matrix Transform(Viewport viewport)
{
    int viewportWidth = viewport.Width;
    int viewportHeight = viewport.Height;

    return
        Matrix.CreateTranslation(new Vector3(-Position.X - viewportWidth / 2, -Position.Y - viewportHeight / 2, 0)) * // Translation Matrix
        Matrix.CreateRotationZ(Rotation) * // Rotation Matrix
        Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) * // Scale Matrix
        Matrix.CreateTranslation(new Vector3(viewportWidth / 2, viewportHeight / 2, 0)); // Origin/Offset Matrix
}

public void Move(Vector2 amount)
{
    Position += amount;
}

还有一个Update()方法，用于检查用户从键盘和鼠标输入的特定内容，例如移动，旋转，缩放。

问题

从我的“变换矩阵”可以看出，当我放大/缩小（递增或递减_zoom）时，我是朝固定的原点（屏幕的中心）进行缩放。

当它朝着鼠标光标缩放时，如何使它如此？

我阅读了一些类似问题的答案，但无法在相机上实现。任何帮助表示赞赏。

Answer 1

在“缩放”之前应用另一个“平移”以将缩放集中在鼠标点上。

public Matrix Transform(Viewport viewport)
{
    int viewportWidth = viewport.Width;
    int viewportHeight = viewport.Height;

    return
        Matrix.CreateTranslation(new Vector3(-Position.X - viewportWidth / 2, -Position.Y - viewportHeight / 2, 0)) * // Translation Matrix
        Matrix.CreateRotationZ(Rotation) * // Rotation Matrix
        Matrix.CreateTranslation(new Vector3(-mouseState.X - viewportWidth / 2, -mouseState.Y - viewportHeight / 2, 0)) * //Mouse Translation Matrix
        Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) * // Scale Matrix
        Matrix.CreateTranslation(new Vector3(viewportWidth / 2, viewportHeight / 2, 0)); // Origin/Offset Matrix
}

如何在MonoGame中以2D缩放鼠标位置

问题

1 个答案: