【发布时间】：2017-05-23 03:38:48
【问题描述】：
在 XNA 游戏中创建视差效果的最佳方法是什么？我希望相机跟随我的精灵在世界各地移动，这样我就可以构建缩放、平移、抖动和其他效果等效果。任何人都有一个如何做到这一点的可靠例子，最好是在 GameComponent 中？
【问题讨论】：
【发布时间】：2017-05-23 03:38:48
【问题描述】：
所以我结合使用上面的教程来解决这个问题，并创建了下面的类。它向您的目标补间并跟随它。试试看。
public interface IFocusable
{
Vector2 Position { get; }
}
public interface ICamera2D
{
/// <summary>
/// Gets or sets the position of the camera
/// </summary>
/// <value>The position.</value>
Vector2 Position { get; set; }
/// <summary>
/// Gets or sets the move speed of the camera.
/// The camera will tween to its destination.
/// </summary>
/// <value>The move speed.</value>
float MoveSpeed { get; set; }
/// <summary>
/// Gets or sets the rotation of the camera.
/// </summary>
/// <value>The rotation.</value>
float Rotation { get; set; }
/// <summary>
/// Gets the origin of the viewport (accounts for Scale)
/// </summary>
/// <value>The origin.</value>
Vector2 Origin { get; }
/// <summary>
/// Gets or sets the scale of the Camera
/// </summary>
/// <value>The scale.</value>
float Scale { get; set; }
/// <summary>
/// Gets the screen center (does not account for Scale)
/// </summary>
/// <value>The screen center.</value>
Vector2 ScreenCenter { get; }
/// <summary>
/// Gets the transform that can be applied to
/// the SpriteBatch Class.
/// </summary>
/// <see cref="SpriteBatch"/>
/// <value>The transform.</value>
Matrix Transform { get; }
/// <summary>
/// Gets or sets the focus of the Camera.
/// </summary>
/// <seealso cref="IFocusable"/>
/// <value>The focus.</value>
IFocusable Focus { get; set; }
/// <summary>
/// Determines whether the target is in view given the specified position.
/// This can be used to increase performance by not drawing objects
/// directly in the viewport
/// </summary>
/// <param name="position">The position.</param>
/// <param name="texture">The texture.</param>
/// <returns>
/// <c>true</c> if the target is in view at the specified position; otherwise, <c>false</c>.
/// </returns>
bool IsInView(Vector2 position, Texture2D texture);
}
public class Camera2D : GameComponent, ICamera2D
{
private Vector2 _position;
protected float _viewportHeight;
protected float _viewportWidth;
public Camera2D(Game game)
: base(game)
{}
#region Properties
public Vector2 Position
{
get { return _position; }
set { _position = value; }
}
public float Rotation { get; set; }
public Vector2 Origin { get; set; }
public float Scale { get; set; }
public Vector2 ScreenCenter { get; protected set; }
public Matrix Transform { get; set; }
public IFocusable Focus { get; set; }
public float MoveSpeed { get; set; }
#endregion
/// <summary>
/// Called when the GameComponent needs to be initialized.
/// </summary>
public override void Initialize()
{
_viewportWidth = Game.GraphicsDevice.Viewport.Width;
_viewportHeight = Game.GraphicsDevice.Viewport.Height;
ScreenCenter = new Vector2(_viewportWidth/2, _viewportHeight/2);
Scale = 1;
MoveSpeed = 1.25f;
base.Initialize();
}
public override void Update(GameTime gameTime)
{
// Create the Transform used by any
// spritebatch process
Transform = Matrix.Identity*
Matrix.CreateTranslation(-Position.X, -Position.Y, 0)*
Matrix.CreateRotationZ(Rotation)*
Matrix.CreateTranslation(Origin.X, Origin.Y, 0)*
Matrix.CreateScale(new Vector3(Scale, Scale, Scale));
Origin = ScreenCenter / Scale;
// Move the Camera to the position that it needs to go
var delta = (float) gameTime.ElapsedGameTime.TotalSeconds;
_position.X += (Focus.Position.X - Position.X) * MoveSpeed * delta;
_position.Y += (Focus.Position.Y - Position.Y) * MoveSpeed * delta;
base.Update(gameTime);
}
/// <summary>
/// Determines whether the target is in view given the specified position.
/// This can be used to increase performance by not drawing objects
/// directly in the viewport
/// </summary>
/// <param name="position">The position.</param>
/// <param name="texture">The texture.</param>
/// <returns>
/// <c>true</c> if [is in view] [the specified position]; otherwise, <c>false</c>.
/// </returns>
public bool IsInView(Vector2 position, Texture2D texture)
{
// If the object is not within the horizontal bounds of the screen
if ( (position.X + texture.Width) < (Position.X - Origin.X) || (position.X) > (Position.X + Origin.X) )
return false;
// If the object is not within the vertical bounds of the screen
if ((position.Y + texture.Height) < (Position.Y - Origin.Y) || (position.Y) > (Position.Y + Origin.Y))
return false;
// In View
return true;
}
}
下面是你将如何使用它与SpriteBatch：
spriteBatch.Begin(SpriteBlendMode.AlphaBlend,
SpriteSortMode.FrontToBack,
SaveStateMode.SaveState,
Camera.Transform);
spriteBatch.Draw(_heliTexture,
_heliPosition,
heliSourceRectangle,
Color.White,
0.0f,
new Vector2(0,0),
0.5f,
SpriteEffects.FlipHorizontally,
0.0f);
spriteBatch.End();
如果这对您有帮助，请告诉我，感谢 StackOverflow 和社区。哇！
【讨论】：
-
我知道这是一个较旧的线程，但它是一个了不起的解决方案，我很乐意实施它以更好地理解它。唯一的问题是我似乎无法让它工作。我已经连接了类的所有部分，它已经初始化，它正在更新，代码中没有抛出任何错误。但是，在运行时，此时在类更新覆盖中会引发 NullReferenceException：_position.X += (Focus.Position.X - Position.X) * MoveSpeed * delta; _position.Y += (Focus.Position.Y - Position.Y) * MoveSpeed * delta;调试器说 camera.Focus 是空的......我一直在尝试一切。有什么想法吗？？
-
哇，好久不见了。但是，如果我正确阅读了我的代码，那么您需要一个精灵来实现一个 IFocusable 接口。然后你需要将该精灵传递给相机。希望这会有所帮助。
-
你是对的！好优雅，谢谢！我试图通过将焦点拍到 Vector2 并绕过使用界面的全部要点来强行使用它，但现在我看到了曙光！非常感谢您的回复:)
-
如果
IFocusableFocus 属性永远不应该为空，那么 ctor 最好是：Camera2D(Game game, IFocusable focused) -
在 Update 方法中，您可能需要在计算变换矩阵之前计算 Origin 属性。否则，使用转换的原点与基于比例的最新计算的原点之间将存在临时差异。此外，您可以只执行 Matrix.CreateScale(Scale) 而不显式创建新的 Vector3。
【讨论】：
-
酷，谢谢。我必须先看看它们，看看它们是否会起作用。
我知道这是一个老问题，但我也有同样的问题，而且我发现了这个很棒的 Monogame 相机库，所以我想我应该分享...
https://github.com/aloisdeniel/Comora
安装非常简单，只需添加即可跟随精灵
this.camera.Position = 精灵的位置；
【讨论】：