跟随身体的相机

Question

移动物体时，相机不会保持居中于物体上。

我似乎无法找到错误。请帮忙。

初始 -

`ConvertUnits.ToDisplayUnits(body.Position)-(Camera._screenCenter- Camera._cameraPosition)`

返回零。

经过一些运动后，它会改变。

我正在使用Farseer Physics Engine 3.5并使用力移动身体。

body.ApplyForce();

这是我的相机类 -

class Camera
    {
        private static Matrix _view;
        public static Vector2 _cameraPosition;
        public static Vector2 _screenCenter;
        private static float _zoom;
        private static float _rotation;

        public static void Load(GraphicsDeviceManager _graphics)
        {
            _view = Matrix.Identity;
            _cameraPosition = Vector2.Zero;
            _screenCenter = new Vector2(_graphics.GraphicsDevice.Viewport.Width / 2f, _graphics.GraphicsDevice.Viewport.Height / 2f);
            _rotation = 0f;
            _zoom = 1.0f;
        }

        public static void HandleInput(KeyboardState state)
        {
            if (state.IsKeyDown(Keys.Add) && _zoom < 1.0f)
                _zoom += 0.1f;
            if (state.IsKeyDown(Keys.Subtract) && _zoom > 0.1f)
                _zoom -= 0.1f;

            Update();
        }

        public static void Update()
        {
            _view = Matrix.CreateTranslation(
                                        new Vector3(_cameraPosition - _screenCenter, 0f)) *
                                         Matrix.CreateRotationZ(_rotation) *
                                         Matrix.CreateScale(new Vector3(_zoom, _zoom, 1)) *
                                         Matrix.CreateTranslation(new Vector3(_screenCenter, 0f));
        }

        public static void Follow(Body body)
        {
            if (body != null)
                _cameraPosition = _screenCenter - ConvertUnits.ToDisplayUnits(body.Position);
        }

        public static Matrix getView()
        {
            return _view;
        }
    }

Answer 1

您的_screenCenter是相机的原点，制作矩阵时无法正确计算。

尝试：

        return Matrix.CreateTranslation(new Vector3(-Position, 0.0f)) *
               Matrix.CreateTranslation(new Vector3(-Origin, 0.0f)) *
               Matrix.CreateRotationZ(Rotation) *
               Matrix.CreateScale(Zoom, Zoom, 1) *
               Matrix.CreateTranslation(new Vector3(Origin, 0.0f));