摘要:XNA-顯示3D模型
XNA預設是支援.x 和.fbx 這兩種3D模型檔案，
而載入模型的方式也非常簡單，先建立一個Model物件，設定好座標，
再畫出來即可，讓我們直接看程式碼吧！
加入以下程式碼：
01 
//模型類別
02Model FD;
03
04
protected override void LoadContent() {
05
// 載入模型
06 FD = Content.Load("FD");
07
}
08
09
protected override void Draw(GameTime gameTime) {
10 graphics.GraphicsDevice.Clear(Color.CornflowerBlue);
11
12 Matrix gameWorldRotation = Matrix.CreateWorld(Vector3.One, Vector3.Forward, Vector3.Up);
13 Matrix[] transforms = new Matrix[FD.Bones.Count];
14 float aspectRatio = graphics.GraphicsDevice.Viewport.Width / graphics.GraphicsDevice.Viewport.Height;
15 FD.CopyAbsoluteBoneTransformsTo(transforms);
16 Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f),
17 aspectRatio, 1.0f, 10000.0f);
18 Matrix view = Matrix.CreateLookAt(new Vector3(0.0f, 50.0f, Zoom), Vector3.Zero, Vector3.Up);
19
20 foreach (ModelMesh mesh in FD.Meshes) {
21 foreach (BasicEffect effect in mesh.Effects) {
22 //使用基本光源打光
23 effect.EnableDefaultLighting();
24
25 effect.View = view;
26 effect.Projection = projection;
27 effect.World = gameWorldRotation * transforms[mesh.ParentBone.Index] * Matrix.CreateTranslation(Vector3.One);
28 }
29 mesh.Draw();
30 }
31
32 base.Draw(gameTime);
33
}
//模型類別 02
Model FD; 03
04
protected override void LoadContent() { 
protected override void LoadContent() 05
// 載入模型 06
FD = Content.Load("FD"); 07
} 08
09
protected override void Draw(GameTime gameTime) { 
protected override void Draw(GameTime gameTime) 10
graphics.GraphicsDevice.Clear(Color.CornflowerBlue); 11
12
Matrix gameWorldRotation = Matrix.CreateWorld(Vector3.One, Vector3.Forward, Vector3.Up); 13
Matrix[] transforms = new Matrix[FD.Bones.Count]; 14
float aspectRatio = graphics.GraphicsDevice.Viewport.Width / graphics.GraphicsDevice.Viewport.Height; 15
FD.CopyAbsoluteBoneTransformsTo(transforms); 16
Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), 17
aspectRatio, 1.0f, 10000.0f); 18
Matrix view = Matrix.CreateLookAt(new Vector3(0.0f, 50.0f, Zoom), Vector3.Zero, Vector3.Up); 19
20
foreach (ModelMesh mesh in FD.Meshes) { 21
foreach (BasicEffect effect in mesh.Effects) { 22
//使用基本光源打光 23
effect.EnableDefaultLighting(); 24
25
effect.View = view; 26
effect.Projection = projection; 27
effect.World = gameWorldRotation * transforms[mesh.ParentBone.Index] * Matrix.CreateTranslation(Vector3.One); 28
} 29
mesh.Draw(); 30
} 31
32
base.Draw(gameTime); 33
}
比較會有問題的應該是20,21兩行，通常一個3D模型不會只有一個部分，幾乎都是由多個不同的小模型組成，
而我們載入模型的時候會將相對位置做階層式記錄，也就是會以一個主要物件為主，
其他物件和此主要物件的相對位置都會被記錄，也因此我們在做旋轉時必須將所有物件一並旋轉，
不然會出現身體轉向了，手腳卻還留在原地的怪異畫面。
而這件事情也非常容易完成，先產生所有物件的矩陣，呼叫Model.Bones.Count可以取得相依的物件數量，
接著將此物件陣列傳入CopyAbsoluteBoneTransformsTo，他會把所有物件的相對位置存到陣列中。
CopyAbsoluteBoneTransformsTo
| public void CopyAbsoluteBoneTransformsTo ( Matrix[] destinationBoneTransforms ) 參數： destinationBoneTransforms 矩陣陣列 |
最後畫出每個部分就完成了！