將攝像頭朝向它所面向的方向

Question

好吧，我是XNA編程的noob，對我來說很裸露。我已經按照教程介紹瞭如何使微軟網站上的XNA中的第一人稱相機旋轉和移動到3D世界中。但是當我沿着它的Y軸旋轉攝像機時，它不會移動它旋轉/朝向的方向，而是像它正面朝它原來面對的方向那樣移動。

這裏是我的代碼：

static Vector3 avatarPosition = new Vector3(0, 0, 0); 
static Vector3 cameraPosition = avatarPosition; 
Vector3 cameraReference = new Vector3(10, 0, 0); 
// Create a vector pointing the direction the camera is facing. 
Matrix world = Matrix.CreateWorld(new Vector3(0, -1, 0), Vector3.Forward, Vector3.Up); 
Matrix rotationMatrix = Matrix.CreateRotationY(MathHelper.ToRadians(0)); 
int Rot = 0; 
Vector3 worldVector = new Vector3(5,-2, 0); 
Matrix view, proj; 
Vector3 cameraLookat; 
Update() 
{ 
    world = Matrix.CreateWorld(worldVector, Vector3.Forward, Vector3.Up); 
    if (IsKeyDown(Keys.W)) 
     avatarPosition += new Vector3(0.2f, 0f, 0); 
    if (IsKeyDown(Keys.S)) 
     avatarPosition += new Vector3(-0.2f, 0f, 0); 
    if (IsKeyDown(Keys.A)) 
     avatarPosition += new Vector3(0f, 0f, -0.2f); 
    if (IsKeyDown(Keys.D)) 
     avatarPosition += new Vector3(0f, 0f, 0.2f); 

    if (IsKeyDown(Keys.Left)) 
     Rot += 1; 
    if (IsKeyDown(Keys.Right)) 
     Rot += -1; 

    rotationMatrix = Matrix.CreateRotationY(MathHelper.ToRadians(Rot)); 
    // Create a vector pointing the direction the camera is facing. 
    Vector3 transformedReference = Vector3.Transform(cameraReference, rotationMatrix); 
    // Calculate the position the camera is looking at. 
    cameraLookat = transformedReference + cameraPosition; 
    // Set up the view matrix and projection matrix. 
    view = Matrix.CreateLookAt(cameraPosition, cameraLookat, new Vector3(0.0f, 1.0f, 0.0f)); 

    proj = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45), graphics.GraphicsDevice.Viewport.AspectRatio, 
              0.1f, 1000); 
    cameraPosition = avatarPosition; 
} 

有人能告訴我爲什麼相機不移動其旋轉的方式嗎？或者有人可以給我這個該死的代碼來製作一個嗎？謝謝。

Answer 1

我看來你遇到的是從該區域的代碼來的問題：

if (IsKeyDown(Keys.W)) 
    avatarPosition += new Vector3(0.2f, 0f, 0); 
if (IsKeyDown(Keys.S)) 
    avatarPosition += new Vector3(-0.2f, 0f, 0); 
if (IsKeyDown(Keys.A)) 
    avatarPosition += new Vector3(0f, 0f, -0.2f); 
if (IsKeyDown(Keys.D)) 
    avatarPosition += new Vector3(0f, 0f, 0.2f); 

直接沿X或Z軸平移avatarPosition的相反，它應該使用你的方向指向看起來是你的transformationReference變量。

例如，向前移動相機對着方式：

if (IsKeyDown(Keys.W)) 
    avatarPosition += transformedReference; 

然而，由於transformedReference出現變量進行歸一化，也可以不移動化身你希望的距離。在這種情況下，簡單地乘以一些常數MOVEMENT_SPEED類似的東西：

if (IsKeyDown(Keys.W)) 
    avatarPosition += transformedReference * MOVEMENT_SPEED;