以編程方式更改SCNScene的sceneNamed

Question

我試圖用代碼更改當前的sceneNamed，但似乎我的方法存在一些問題。首先，新的場景會改變，但我必須觸摸或評價對象，以改變過程發生。第二，看起來childNodeWithName根本不會改變！這裏是我的代碼：

- (void)load3DObjectName:(NSString*)name nodeName:(NSString*)nodeName zPhone:(CGFloat)positioniPhone zPad:(CGFloat)positioniPad{ 

     SCNScene * scene = [SCNScene sceneNamed:name]; 
     // retrieve the ship node 
     SCNNode *trex = [scene.rootNode childNodeWithName:nodeName recursively:YES]; 


     if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone) { 

      trex.position = SCNVector3Make(0, 0, positioniPhone); 

     } else { 

      trex.position = SCNVector3Make(0, 0, positioniPad); 
     } 



     _the3DScence.scene = scene; 
     _the3DScence.autoenablesDefaultLighting = YES; 
     _the3DScence.allowsCameraControl = YES; 
     _the3DScence.backgroundColor = [UIColor colorWithRed:0.92 green:0.92 blue:0.92 alpha:1.00]; 
    } 



// Load default object : 

- (void)viewDidLoad { 

    [self load3DObjectName:@"cube.dae" nodeName:@"cube1" zPhone:-40 zPad:-30]; 

} 

//Trying to change the 3D object with button: 
- (IBAction)nextObject:(id)sender { 

    [self load3DObjectName:@"redCube.dae" nodeName:@"cube2" zPhone:-40 zPad:-30]; 

} 

- (IBAction)changeIt:(id)sender { 

    [self load3DObjectName:@"dayere.dae" nodeName:@"Sphere" zPhone:-40 zPad:-40]; 
} 

這裏是一個源代碼： https://www.dropbox.com/s/rrvbxmrb9wcrnoj/3D%20Objects%20Change.zip?dl=0

在Dropbox的版本的代碼是不是我張貼以上。這裏是Dropbox版本：

 
- (void)viewDidLoad { 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view, typically from a nib. 

    [self load3DObjectName:@"cube.dae" nodeName:@"Cube" zPhone:-40 zPad:-40]; 
} 

- (void)didReceiveMemoryWarning { 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

- (void)load3DObjectName:(NSString*)name nodeName:(NSString*)nodeName zPhone:(CGFloat)positioniPhone zPad:(CGFloat)positioniPad{ 
    SCNScene * scene = [SCNScene sceneNamed:name]; 
    // retrieve the ship node 
    SCNNode *node = [scene.rootNode childNodeWithName:nodeName recursively:YES]; 

    if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone) { 
     node.position = SCNVector3Make(0, 0, positioniPhone); 
    } 
    else { 
     node.position = SCNVector3Make(0, 0, positioniPad); 
    } 
    _the3DView.scene = scene; 
    _the3DView.autoenablesDefaultLighting = YES; 
    _the3DView.allowsCameraControl = YES; 
    _the3DView.backgroundColor = [UIColor colorWithRed:0.92 green:0.92 blue:0.92 alpha:1.00]; 
} 

- (IBAction)changeIt:(id)sender { 
    [self load3DObjectName:@"dayere.dae" nodeName:@"Sphere" zPhone:-40 zPad:-40]; 
} 

Answer 1

所以我拿看看你的項目。問題在於：你在場景中沒有攝像頭。所以我在相同的距離手動爲每個場景放置相機，並根據需要移動節點。這裏是什麼樣子現在：

- (void)load3DObjectName:(NSString*)name nodeName:(NSString*)nodeName zPhone:(CGFloat)positioniPhone zPad:(CGFloat)positioniPad 
{ 
SCNScene * scene = [SCNScene sceneNamed:name]; 
SCNNode *node = [scene.rootNode childNodeWithName:nodeName recursively:YES]; 

if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone) 
{ 
    node.position = SCNVector3Make(0, 0, positioniPhone); 

} else { 

    node.position = SCNVector3Make(0, 0, positioniPad); 
} 

SCNCamera *cam = [[SCNCamera alloc] init]; 
cam.xFov = 35; 
cam.yFov = 35; 
cam.zFar = 5000; 
cam.zNear = 0; 
SCNNode *camNode = [[SCNNode alloc] init]; 
camNode.camera = cam; 

camNode.position = SCNVector3Make(0, 0, 400); 

[scene.rootNode addChildNode:camNode]; 

_the3DView.pointOfView = camNode; 

_the3DView.scene = scene; 
_the3DView.autoenablesDefaultLighting = YES; 
_the3DView.allowsCameraControl = YES; 
_the3DView.backgroundColor = [UIColor colorWithRed:0.92 green:0.92 blue:0.92 alpha:1.00]; 
} 

，我也改變爲測試目的而你的對象的位置：

- (IBAction)changeIt:(id)sender 
{ 
[self load3DObjectName:@"dayere.dae" nodeName:@"Sphere" zPhone:-340 zPad:-340]; 
} 

而這其中還有：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    [self load3DObjectName:@"cube.dae" nodeName:@"Cube" zPhone:-40 zPad:-40]; 
} 

最後，但並非最不重要，屏幕截圖：

Answer 2

它在我看來像你的第二輪代碼工作正常。我注意到您在Dropbox示例中加載的不同場景/節點比您首先發布的代碼中的不同。所以這讓我覺得你的DAE文件中有一些不是你期望的東西。檢查缺少或拼寫錯誤的節點名稱。在調用childNodeWithName:和sceneNamed:之後，請添加NSAssert調用，以確保您確實已成功加載場景並找到子節點。

SCNScene * scene = [SCNScene sceneNamed:name]; 
NSAssert(scene, @"failed to load scene named %@", name); 
// retrieve the ship node 
SCNNode *node = [scene.rootNode childNodeWithName:nodeName recursively:YES]; 
NSAssert(node, @"couldn't fine child node named %@", nodeName); 

如果NSAsserts失敗，請使用您的3D編輯工具來修復您的Collada文件。

還要注意，當你替換the3DView.scene（拋開：請不要直接調用實例變量，而是使用訪問器方法！），你也會替換相機和燈光。所以你應該期待相機定位的一個混蛋。也許你想要這個動畫？或者刪除/替換對象的節點，而不會搞亂相機和照明？

當我運行您發佈到Dropbox的代碼時，我看到一個充滿紅色的屏幕。當我放大了，而旋轉的攝像頭，它看起來像這樣：

我點擊的「按鈕」按鈕後，我看到：