SceneKit：使用平移手势将相机朝其面向的方向移动

Question

我在我的 SceneKit 游戏中设置了一些自定义相机控件。我在基于相机 y 欧拉角的平移手势自动适应方面遇到问题。我的平移手势通过在 x 和 z 轴上平移相机（通过使用手势转换）来工作。问题是，尽管相机旋转，相机将继续在 x 和 z 轴上平移。我想要它，以便相机在其面向的轴上平移。

这是我用来 pan/rotate:

的手势

平移：

var previousTranslation = SCNVector3(x: 0.0,y: 15,z: 0.0)
var lastWidthRatio:Float = 0
var angle:Float = 0

@objc func pan(gesture: UIPanGestureRecognizer) {
    gesture.minimumNumberOfTouches = 1
    gesture.maximumNumberOfTouches = 1
    if gesture.numberOfTouches == 1 {
        let view = self.view as! SCNView
        let node = view.scene!.rootNode.childNode(withName: "Node", recursively: false)
        let secondNode =  view.scene!.rootNode.childNode(withName: "CameraHandler", recursively: false)
        let translation = gesture.translation(in: view)

        let constant: Float = 30.0
        angle = secondNode!.eulerAngles.y
        //these were the previous values I was using to handle panning, they worked but provided really jittery movement. You can change the direction they rotate by multiplying the sine/cosine .pi values by any integer.
        //var translateX = Float(translation.y) * sin(.pi) / cos(.pi) - Float(translation.x) * cos(.pi)
        //var translateY = Float(translation.y) * cos(.pi) / cos(.pi) + Float(translation.x) * sin(.pi)

        //these ones work a lot smoother
        var translateX = Float(translation.x) * Float(Double.pi / 180)
        var translateY = Float(translation.y) * Float(Double.pi / 180)
        translateX = translateX * constant
        translateY = translateY * constant

        switch gesture.state {
        case .began:
            previousTranslation = node!.position
            break;
        case .changed:
            node!.position = SCNVector3Make((previousTranslation.x + translateX), previousTranslation.y, (previousTranslation.z + translateY))
            break
        default: break
        }
    }
}

旋转：

@objc func rotate(gesture: UIPanGestureRecognizer) {
    gesture.minimumNumberOfTouches = 2
    gesture.maximumNumberOfTouches = 2
    if gesture.numberOfTouches == 2 {
        let view = self.view as! SCNView
        let node = view.scene!.rootNode.childNode(withName: "CameraHandler", recursively: false)
        let translate = gesture.translation(in: view)

        var widthRatio:Float = 0

        widthRatio = Float(translate.x / 10) * Float(Double.pi / 180)

        switch gesture.state {
        case .began:
            lastWidthRatio = node!.eulerAngles.y
            break
        case .changed:
            node!.eulerAngles.y = lastWidthRatio + widthRatio
            print(node!.eulerAngles.y)
            break
        default: break
        }
    }
}

CameraHandler节点是Camera节点的父节点。一切正常，只是没有像我想要的那样工作。希望这对你们来说已经足够清楚了。

Answer 1

在Objective C。关键部分是最后三行，特别是最后一行中矩阵的乘法顺序（导致移动发生在局部space）。如果 transmat 和 cammat 切换，它会像现在一样再次运行（在世界中移动 space）。重构部分只适用于我的特定情况，在这种情况下，透视和正交相机都是可能的。

-(void)panCamera :(CGPoint)location {

CGFloat dx = _prevlocation.x - location.x;
CGFloat dy = location.y - _prevlocation.y;
_prevlocation = location;

//refactor dx and dy based on camera distance or orthoscale
if (cameraNode.camera.usesOrthographicProjection) {
    dx = dx / 416 * cameraNode.camera.orthographicScale;
    dy = dy / 416 * cameraNode.camera.orthographicScale;
} else {
    dx = dx / 720 * cameraNode.position.z;
    dy = dy / 720 * cameraNode.position.z;
}

SCNMatrix4 cammat = self.cameraNode.transform;
SCNMatrix4 transmat = SCNMatrix4MakeTranslation(dx, 0, dy);
self.cameraNode.transform = SCNMatrix4Mult(transmat, cammat);

}

Answer 2

根据 Xartec 的回答，我明白了。我将其翻译成 swift 和 retro-fitted 来满足我的需要。我对它不是很满意，因为运动不流畅。今天晚些时候我会努力把它弄平。

平移手势：此手势沿相机旋转的方向在场景周围平移相机父节点。它完全符合我的要求。

@objc func pan(gesture: UIPanGestureRecognizer) {
    gesture.minimumNumberOfTouches = 1
    gesture.maximumNumberOfTouches = 1
    if gesture.numberOfTouches == 1 {
        let view = self.view as! SCNView
        let node = view.scene!.rootNode.childNode(withName: "CameraHandler", recursively: false)
        let translation = gesture.translation(in: view)

        var dx = previousTranslation.x - translation.x
        var dy = previousTranslation.y - translation.y

        dx = dx / 100
        dy = dy / 100
        print(dx,dy)

        let cammat = node!.transform
        let transmat = SCNMatrix4MakeTranslation(Float(dx), 0, Float(dy))

        switch gesture.state {
        case .began:
            previousTranslation = translation
            break;
        case .changed:
            node!.transform = SCNMatrix4Mult(transmat, cammat)
            break
        default: break
        }
    }
}

旋转手势：此手势用两根手指旋转相机。

@objc func rotate(gesture: UIPanGestureRecognizer) {
    gesture.minimumNumberOfTouches = 2
    gesture.maximumNumberOfTouches = 2
    if gesture.numberOfTouches == 2 {
        let view = self.view as! SCNView
        let node = view.scene!.rootNode.childNode(withName: "CameraHandler", recursively: false)
        let translate = gesture.translation(in: view)

        var widthRatio:Float = 0
        widthRatio = Float(translate.x / 10) * Float(Double.pi / 180)

        switch gesture.state {
        case .began:
            lastWidthRatio = node!.eulerAngles.y
            break
        case .changed:
            node!.eulerAngles.y = lastWidthRatio + widthRatio
            break
        default: break
        }
    }
}

要获得与我相同的功能，您需要将 cameraNode 附加到父节点。像这样：

    //create and add a camera to the scene
    let cameraNode = SCNNode()

    //cameraHandler is declared outside viewDidLoad. 
    let cameraHandler = SCNNode()

    cameraNode.camera = SCNCamera()
    cameraNode.name = "Camera"
    cameraNode.position = SCNVector3(x: 0.0,y: 10.0,z: 20.0)
    //This euler angle only rotates the camera downward a little bit. It is not neccessary 
    cameraNode.eulerAngles = SCNVector3(x: -0.6, y: 0, z: 0)

    cameraHandler.addChildNode(cameraNode)
    cameraHandler.name = "CameraHandler"

    scene.rootNode.addChildNode(cameraHandler)

SceneKit：使用平移手势将相机朝其面向的方向移动

SceneKit: move camera towards direction its facing with pan gesture

rotation

panning

ios

scenekit

swift