移动相机对准它指向的方向同时转动考虑 [英] move a camera toward it pointing direction taking rotation into consideration

问题描述

可以说我们与位于不同的XYZ位置和旋转物体的场景。 其中一个节点是，我要走向画面的虚点，例如中心（512，384），向前或向后一台照相机。通过屏幕中心我指的是相机的方向的中心，所以它的什么用户可以看到。我面对目前的问题是：

1. 在虚点（512，384）在2D以及如何将其转换成3D
2. 如何移动摄像机向前/向后走转成 审议

有例如，照相机具有当前位置（x，Y，Z）（140，199，20），并绕其轴（x，Y，Z）（25°，187°，301°）转动。因此如何将相机对准它的指向方向。 我在学习现场套件（包括新3D）和任何例子/伪code是多少AP preciated。

我的努力，到现在只有移动相机对准根节点。

  [_cameraNode runAction：[SCNAction MOVETO：。SCNVector3Make（_cameraNode presentationNode.position.x，_cameraNode presentationNode.position.y，_cameraNode presentationNode .position.z  -  5）时间：1];
 

解决方案

根据@mnuages​​发表评论，我可以采取必要的code出来，达到我要求的。谢谢！

   - （SCNVector3）位置：（SCNVector3）位置multipliedByRotation：（SCNVector4）旋转
{
   如果（rotation.w == 0）
   {
       返回的位置;
   }
   GLKVector3 gPosition = SCNVector3ToGLKVector3（位置）;
   GLKMatrix4 gRotation = GLKMatrix4MakeRotation（rotation.w，rotation.x，rotation.y，rotation.z）;
   GLKVector3 R = GLKMatrix4MultiplyVector3（gRotation，gPosition）;
   返回SCNVector3FromGLKVector3（r）的;
 }

 - （SCNMatrix4）moveCamera
{
   CGFloat的步长= 2.0
   CGFloat的X = 0.0;
   CGFloat的Y = 0.0;
   CGFloat的Z = _touchCount == 2？ - 步骤：_touchCount == 1？步骤：0.0;

   SCNMatrix4 cameraTransform = _cameraNode.transform;

   SCNVector3 rotatedPosition = [自我定位：SCNVector3Make（X，Y，Z）multipliedByRotation：_cameraNode.rotation]。
   cameraTransform = SCNMatrix4Translate（cameraTransform，rotatedPosition.x，rotatedPosition.y，rotatedPosition.z）;

    返回cameraTransform;
}
 

lets say we have a scene with objects located in different xyz positions and rotations. one of the nodes is a camera which I want to move toward an imaginary point e.g center of screen(512, 384) backward or forward. by center of screen I mean center of a direction of a camera, so its what the user can see. the problems I'm facing currently are:

1. imaginary point (512, 384) is in 2D and how to convert that to 3D
2. how to move the camera forward/backward taking rotation into consideration

for instance, the camera has current location (x,y,z)(140, 199, 20) and is rotated around its axis (x,y,z)(25°, 187°, 301°). so how to move the camera toward its pointing direction. I'm learning scene kit (incl. new to 3D) and any example/pseudo code is much appreciated.

my efforts till now only moves the camera toward root node.

    [_cameraNode runAction:[SCNAction moveTo:SCNVector3Make(_cameraNode.presentationNode.position.x, _cameraNode.presentationNode.position.y, _cameraNode.presentationNode.position.z - 5) duration:1]];

解决方案

according @mnuages comment I could take the necessary code out and achieve what i asked for. thank you!

-(SCNVector3)position:(SCNVector3)position multipliedByRotation:(SCNVector4)rotation
{
   if (rotation.w == 0)
   {
       return position;
   }
   GLKVector3 gPosition = SCNVector3ToGLKVector3(position);
   GLKMatrix4 gRotation = GLKMatrix4MakeRotation(rotation.w, rotation.x, rotation.y, rotation.z);
   GLKVector3 r = GLKMatrix4MultiplyVector3(gRotation, gPosition);
   return SCNVector3FromGLKVector3(r);
 }

-(SCNMatrix4)moveCamera
{
   CGFloat step = 2.0
   CGFloat x = 0.0;
   CGFloat y = 0.0;
   CGFloat z = _touchCount == 2 ? -step : _touchCount == 1 ? step : 0.0;

   SCNMatrix4 cameraTransform = _cameraNode.transform;

   SCNVector3 rotatedPosition = [self position:SCNVector3Make(x, y, z) multipliedByRotation: _cameraNode.rotation];
   cameraTransform = SCNMatrix4Translate(cameraTransform, rotatedPosition.x, rotatedPosition.y, rotatedPosition.z);

    return cameraTransform;
}

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