如何检测ARAnchor当前是否在相机中可见，我需要测试相机视图何时发生变化。 我想在不在屏幕上时将箭头放在屏幕边缘指向锚点的方向。我需要知道节点是否位于平截头体的左侧或右侧。
我现在正在这样做，但它表示如果不是并且X值看起来不对，那么引脚是可见的吗？也许渲染器视锥体与屏幕相机不匹配？
var deltaTime = TimeInterval()
public func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
deltaTime = time - lastUpdateTime
if deltaTime>1{
if let annotation = annotationsByNode.first {
let node = annotation.key.childNodes[0]
if !renderer.isNode(node, insideFrustumOf: renderer.pointOfView!)
{
print("Pin is not visible");
}else {
print("Pin is visible");
}
let pnt = renderer.projectPoint(node.position)
print("pos ", pnt.x, " ", renderer.pointOfView!.position)
}
lastUpdateTime = time
}
}
更新：代码用于显示节点是否可见，如何判断节点相对于相机平截头的左或右方向？
UPDATE2！正如Bhanu Birani的建议答案
let screenWidth = UIScreen.main.bounds.width
let screenHeight = UIScreen.main.bounds.height
let leftPoint = CGPoint(x: 0, y: screenHeight/2)
let rightPoint = CGPoint(x: screenWidth,y: screenHeight/2)
let leftWorldPos = renderer.unprojectPoint(SCNVector3(leftPoint.x,leftPoint.y,0))
let rightWorldPos = renderer.unprojectPoint(SCNVector3(rightPoint.x,rightPoint.y,0))
let distanceLeft = node.position - leftWorldPos
let distanceRight = node.position - rightWorldPos
let dir = (isVisible) ? "visible" : ( (distanceLeft.x<distanceRight.x) ? "left" : "right")
我最终使用了屏幕左右两侧的Bhanu Birani的想法，但是我得到了不同的世界位置，unProjectPoint并且还获得了距离的标量值，我将其与左/右方向进行比较。也许有更好的方法，但它对我有用
public func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
deltaTime = time - lastUpdateTime
if deltaTime>0.25{
if let annotation = annotationsByNode.first {
guard let pointOfView = renderer.pointOfView else {return}
let node = annotation.key.childNodes[0]
let isVisible = renderer.isNode(node, insideFrustumOf: pointOfView)
let screenWidth = UIScreen.main.bounds.width
let screenHeight = UIScreen.main.bounds.height
let leftPoint = CGPoint(x: 0, y: screenHeight/2)
let rightPoint = CGPoint(x: screenWidth,y: screenHeight/2)
let leftWorldPos = renderer.unprojectPoint(SCNVector3(leftPoint.x, leftPoint.y,0))
let rightWorldPos = renderer.unprojectPoint(SCNVector3(rightPoint.x, rightPoint.y,0))
let distanceLeft = node.worldPosition.distance(vector: leftWorldPos)
let distanceRight = node.worldPosition.distance(vector: rightWorldPos)
//let pnt = renderer.projectPoint(node.worldPosition)
//guard let pnt = renderer.pointOfView!.convertPosition(node.position, to: nil) else {return}
let dir = (isVisible) ? "visible" : ( (distanceLeft<distanceRight) ? "left" : "right")
print("dir" , dir, " ", leftWorldPos , " ", rightWorldPos)
lastDir=dir
delegate?.nodePosition?(node:node, pos: dir)
}else {
delegate?.nodePosition?(node:nil, pos: lastDir )
}
lastUpdateTime = time
}
extension SCNVector3
{
/**
* Returns the length (magnitude) of the vector described by the SCNVector3
*/
func length() -> Float {
return sqrtf(x*x + y*y + z*z)
}
/**
* Calculates the distance between two SCNVector3. Pythagoras!
*/
func distance(vector: SCNVector3) -> Float {
return (self - vector).length()
}
}
答案 0 :(得分：11)
从以下屏幕位置投射光线：
leftPoint = CGPoint(0, screenHeight/2)（屏幕左侧）rightPoint = CGPoint(screenWidth, screenHeight/2)（屏幕中间右侧）将CGPoint转换为世界位置：
leftWorldPos = convertCGPointToWorldPosition(leftPoint) rightWorldPos = convertCGPointToWorldPosition(rightPoint) 计算节点距世界两个位置的距离：
distanceLeft = node.position - leftWorldPos distanceRight = node.position - rightWorldPos 比较距离以找到到节点的最短距离。使用最短距离矢量来定位对象的方向箭头。
以下是来自tsukimi的代码，用于检查对象是在屏幕的右侧还是在左侧：
public func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
deltaTime = time - lastUpdateTime
if deltaTime>0.25{
if let annotation = annotationsByNode.first {
guard let pointOfView = renderer.pointOfView else {return}
let node = annotation.key.childNodes[0]
let isVisible = renderer.isNode(node, insideFrustumOf: pointOfView)
let screenWidth = UIScreen.main.bounds.width
let screenHeight = UIScreen.main.bounds.height
let leftPoint = CGPoint(x: 0, y: screenHeight/2)
let rightPoint = CGPoint(x: screenWidth,y: screenHeight/2)
let leftWorldPos = renderer.unprojectPoint(SCNVector3(leftPoint.x, leftPoint.y,0))
let rightWorldPos = renderer.unprojectPoint(SCNVector3(rightPoint.x, rightPoint.y,0))
let distanceLeft = node.worldPosition.distance(vector: leftWorldPos)
let distanceRight = node.worldPosition.distance(vector: rightWorldPos)
//let pnt = renderer.projectPoint(node.worldPosition)
//guard let pnt = renderer.pointOfView!.convertPosition(node.position, to: nil) else {return}
let dir = (isVisible) ? "visible" : ( (distanceLeft<distanceRight) ? "left" : "right")
print("dir" , dir, " ", leftWorldPos , " ", rightWorldPos)
lastDir=dir
delegate?.nodePosition?(node:node, pos: dir)
}else {
delegate?.nodePosition?(node:nil, pos: lastDir )
}
lastUpdateTime = time
}
以下是帮助对vector执行操作的类
extension SCNVector3 {
init(_ vec: vector_float3) {
self.x = vec.x
self.y = vec.y
self.z = vec.z
}
func length() -> Float {
return sqrtf(x * x + y * y + z * z)
}
mutating func setLength(_ length: Float) {
self.normalize()
self *= length
}
mutating func setMaximumLength(_ maxLength: Float) {
if self.length() <= maxLength {
return
} else {
self.normalize()
self *= maxLength
}
}
mutating func normalize() {
self = self.normalized()
}
func normalized() -> SCNVector3 {
if self.length() == 0 {
return self
}
return self / self.length()
}
static func positionFromTransform(_ transform: matrix_float4x4) -> SCNVector3 {
return SCNVector3Make(transform.columns.3.x, transform.columns.3.y, transform.columns.3.z)
}
func friendlyString() -> String {
return "(\(String(format: "%.2f", x)), \(String(format: "%.2f", y)), \(String(format: "%.2f", z)))"
}
func dot(_ vec: SCNVector3) -> Float {
return (self.x * vec.x) + (self.y * vec.y) + (self.z * vec.z)
}
func cross(_ vec: SCNVector3) -> SCNVector3 {
return SCNVector3(self.y * vec.z - self.z * vec.y, self.z * vec.x - self.x * vec.z, self.x * vec.y - self.y * vec.x)
}
}
extension SCNVector3{
func distance(receiver:SCNVector3) -> Float{
let xd = receiver.x - self.x
let yd = receiver.y - self.y
let zd = receiver.z - self.z
let distance = Float(sqrt(xd * xd + yd * yd + zd * zd))
if (distance < 0){
return (distance * -1)
} else {
return (distance)
}
}
}
以下是将抽头位置或任何CGPoint转换为世界变换的代码段。
@objc func handleTap(_ sender: UITapGestureRecognizer) {
// Take the screen space tap coordinates and pass them to the hitTest method on the ARSCNView instance
let tapPoint = sender.location(in: sceneView)
let result = sceneView.hitTest(tapPoint, types: ARHitTestResult.ResultType.existingPlaneUsingExtent)
// If the intersection ray passes through any plane geometry they will be returned, with the planes
// ordered by distance from the camera
if (result.count > 0) {
// If there are multiple hits, just pick the closest plane
if let hitResult = result.first {
let finalPosition = SCNVector3Make(hitResult.worldTransform.columns.3.x + insertionXOffset,
hitResult.worldTransform.columns.3.y + insertionYOffset,
hitResult.worldTransform.columns.3.z + insertionZOffset
);
}
}
}
以下是在没有发现飞机时获得命中测试结果的代码。
// check what nodes are tapped
let p = gestureRecognize.location(in: scnView)
let hitResults = scnView.hitTest(p, options: [:])
// check that we clicked on at least one object
if hitResults.count > 0 {
// retrieved the first clicked object
let result = hitResults[0]
}
答案 1 :(得分：0)
这个答案有点晚，但对于需要知道节点相对于中心的相机空间位置的人（例如左上角，居中......）非常有用。
您可以使用scene.rootNode.convertPosition（node.position，to：pointOfView）在相机空间中获取节点位置。
在相机空间，
（isVisible＆amp;＆amp;（x = 0，y = 0））表示您的节点位于相机前面。
（isVisible＆amp;＆amp;（x = 0.1））表示该节点位于右侧。
一些示例代码：
public func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
deltaTime = time - lastUpdateTime
if deltaTime>0.25{
if let annotation = annotationsByNode.first {
guard let pointOfView = renderer.pointOfView else {return}
let node = annotation.key.childNodes[0]
let isVisible = renderer.isNode(node, insideFrustumOf: pointOfView)
// Translate node to camera space
let nodeInCameraSpace = scene.rootNode.convertPosition(node.position, to: pointOfView)
let isCentered = isVisible && (nodeInCameraSpace.x < 0.1) && (nodeInCameraSpace.y < 0.1)
let isOnTheRight = isVisible && (nodeInCameraSpace.x > 0.1)
// ...
delegate?.nodePosition?(node:node, pos: dir)
}else {
delegate?.nodePosition?(node:nil, pos: lastDir )
}
lastUpdateTime = time
}