I was trying to find the position of the closest Plane in my ARKit app. I wrote some code to help find it, but for some reason, when I run my app, it keeps crashing when I try to add an AR object to the plane. Is there something wrong with my code?
struct myPlaneCoords {
var x = Float()
var y = Float()
var z = Float()
}
func getPlaneCoordinates(sceneView: ARSCNView) -> myPlaneCoords{//coordinates where an AR node will be added
let cameraTransform = sceneView.session.currentFrame?.camera.transform
let cameraCoordinates = MDLTransform(matrix: cameraTransform!)
let camX = CGFloat(cameraCoordinates.translation.x)
let camY = CGFloat(cameraCoordinates.translation.y)
let cameraPosition = CGPoint(x: camX, y: camY)
let anchors = sceneView.hitTest(cameraPosition, types: ARHitTestResult.ResultType.existingPlane)
let spefAnchor = MDLTransform(matrix: anchors[0].localTransform)//finds closest plane
var cc = myPlaneCoords()
cc.x = spefAnchor.translation.x
cc.y = spefAnchor.translation.y
cc.z = spefAnchor.translation.z
return cc
}
Difficult to judge w/o exception description.
I can assume that hitTest doesn't detect any anchor.
In such case your anchors is empty.
let spefAnchor = MDLTransform(matrix: anchors[0].localTransform)//finds closest plane
And here you should get a crash.
Related
I am trying to implement a function that allows the user to tap and add a node to the to a scene at the location where the user clicked. I would like this to be on a plane. I did some research and found the following function, but I get the warning Value of type 'simd_float4x4' has no member 'translation' on the line let translation = hitTestResult.worldTransform.translation
Does anyone know how I can change this so I am not getting the warning?
#objc func addRoomToSceneView(withGestureRecognizer recognizer: UIGestureRecognizer) {
let tapLocation = recognizer.location(in: sceneView)
let hitTestResults = sceneView.hitTest(tapLocation, types: .existingPlaneUsingExtent)
guard let hitTestResult = hitTestResults.first else { return }
//THE FOLLOWING LINE HAS THE warning: Value of type 'simd_float4x4' has no member 'translation'
let translation = hitTestResult.worldTransform.translation
let x = translation.x
let y = translation.y
let z = translation.z
let room = createMaskedRectangleRoom(width: 4, height: 4, depth: 4, color: .white)
room.scale = SCNVector3(2, 2, 2)
room.position = SCNVector3(x,y,z)
sceneView.scene.rootNode.addChildNode(room)
}
The result of hitResult.worldTransform is an SCNMatrix4 and a 4x4 matrix has no translation property. When applied to a point using matrix multiplication the transformation done might include a translation, but the underlying data type is essentially a 16 element rectangular array.
You can probably extract the translation aspect of the matrix with:
let translation = SCNVector4(float4x4(hitTestResult.worldTransform) * SIMD4<Float>(0,0,0,1))
I'm assuming the hitTestResult.worldTransform matrix is affine. It would be weird if it were not.
I am creating an iOS AR app that sets text in a specific location and leaves it there for others to view. Is there a better way to implement it than what I am doing?
Currently, I have it set so that the text is saved to Firebase and loads it by setting the nodes relative to the camera’s position. I’m wondering if there is a way to save ARAnchors in a fashion similar to what I am doing but is that possible?
My current function for saving the text to the location via a user tapping the screen:
/*
* Variables for saving the user touch
*/
var touchX : Float = 0.0
var touchY : Float = 0.0
var touchZ : Float = 0.0
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
// will be used for getting the text
let textNode = SCNNode()
var writing = SCNText()
// gets the user’s touch upon tapping the screen
guard let touch = touches.first else {return}
let result = sceneView.hitTest(touch.location(in: sceneView), types: [ARHitTestResult.ResultType.featurePoint])
guard let hitResult = result.last else {return}
let hitTransform = SCNMatrix4.init(hitResult.worldTransform)
let hitVector = SCNVector3Make(hitTransform.m41, hitTransform.m42, hitTransform.m43)
// saves X, Y, and Z coordinates of touch relative to the camera
touchX = hitTransform.m41
touchY = hitTransform.m42
touchZ = hitTransform.m43
// Was thinking of adding the ability to change colors. Probably can skip next seven lines
var colorArray = [UIColor]()
colorArray.append(UIColor.red)
writing = SCNText(string: input.text, extrusionDepth: 1)
material.diffuse.contents = colorArray[0]
writing.materials = [material]
// modifies the node’s position and size
textNode.scale = SCNVector3(0.01, 0.01, 0.01)
textNode.geometry = writing
textNode.position = hitVector
sceneView.scene.rootNode.addChildNode(textNode)
// last few lines save the info to Firebase
let values = ["X" : touchX, "Y" : touchY, "Z" : touchZ, "Text" : input.text!] as [String : Any]
let childKey = reference.child("Test").childByAutoId().key
if input.text != nil && input.text != "" {
let child = reference.child("Test").child(childKey!)
child.updateChildValues(values)
} else {
let child = reference.child("Test").child(childKey!)
child.updateChildValues(values)
} // if
} // override func
/*
* Similar to the previous function but used in next function
*/
func placeNode(x: Float, y: Float, z: Float, text: String) -> Void {
let textNode = SCNNode()
var writing = SCNText()
let hitVector = SCNVector3Make(x, y, z)
touchX = x
touchY = y
touchZ = z
var colorArray = [UIColor]()
colorArray.append(UIColor.red)
writing = SCNText(string: text, extrusionDepth: 1)
material.diffuse.contents = colorArray[0]
writing.materials = [material]
textNode.scale = SCNVector3(0.01, 0.01, 0.01)
textNode.geometry = writing
textNode.position = hitVector
sceneView.scene.rootNode.addChildNode(textNode)
} // func
/*
* This next function is used in my viewDidLoad to load the data
*/
func handleData() {
reference.child("Test").observeSingleEvent(of: .value, with: { (snapshot) in
if let result = snapshot.children.allObjects as? [DataSnapshot] {
for child in result {
let xCoord = Float(truncating: child.childSnapshot(forPath: "X").value as! NSNumber)
let yCoord = Float(truncating: child.childSnapshot(forPath: "Y").value as! NSNumber)
let zCoord = Float(truncating: child.childSnapshot(forPath: "Z").value as! NSNumber)
let inscription = child.childSnapshot(forPath: "Text").value
self.placeNode(x: xCoord , y: yCoord , z: zCoord , text: inscription as! String)
} // for
} // if
}) // reference
} // func
I have looked into a few things such as ARCore but that looks like it uses Objective-C. I’ve made this app in Swift and I am not sure if I can incorporate ARCore with how I have implemented my current application.
Do I just need to get over it and learn Objective-C? Can I still work with what I have?
I think that ARCore anchors are only available for 24 hours, so that could be a problem.
You probably need to use ARKit2.0's ARWorldMap and save it as data on firebase for others to see the text in the same place, otherwise you are assuming in your code that future users will start their AR session in the exact same position and direction as the person who left the text. You probably need to use core location first to see where in the world the user is.
I'm creating an anchor and adding it to my ARSKView at a certain distance in front of the camera like this:
func displayToken(distance: Float) {
print("token dropped at: \(distance)")
guard let sceneView = self.view as? ARSKView else {
return
}
// Create anchor using the camera's current position
if let currentFrame = sceneView.session.currentFrame {
// Create a transform with a translation of x meters in front of the camera
var translation = matrix_identity_float4x4
translation.columns.3.z = -distance
let transform = simd_mul(currentFrame.camera.transform, translation)
// Add a new anchor to the session
let anchor = ARAnchor(transform: transform)
sceneView.session.add(anchor: anchor)
}
}
then the node gets created for the anchor like this:
func view(_ view: ARSKView, nodeFor anchor: ARAnchor) -> SKNode? {
// Create and configure a node for the anchor added to the view's session.
if let image = tokenImage {
let texture = SKTexture(image: image)
let tokenImageNode = SKSpriteNode(texture: texture)
tokenImageNode.name = "token"
return tokenImageNode
} else {
return nil
}
}
This works fine and I see the image get added at the appropriate distance. However, what I'm trying to do is then calculate how far the anchor/node is in front of the camera as you move. The problem is the calculation seems to be off immediately using fabs(cameraZ - anchor.transform.columns.3.z). Please see my code below that is in the update() method to calculate distance between camera and object:
override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
guard let sceneView = self.view as? ARSKView else {
return
}
if let currentFrame = sceneView.session.currentFrame {
let cameraZ = currentFrame.camera.transform.columns.3.z
for anchor in currentFrame.anchors {
if let spriteNode = sceneView.node(for: anchor), spriteNode.name == "token", intersects(spriteNode) {
// token is within the camera view
//print("token is within camera view from update method")
print("DISTANCE BETWEEN CAMERA AND TOKEN: \(fabs(cameraZ - anchor.transform.columns.3.z))")
print(cameraZ)
print(anchor.transform.columns.3.z)
}
}
}
}
Any help is appreciated in order to accurately get distance between camera and the anchor.
The last column of a 4x4 transform matrix is the translation vector (or position relative to a parent coordinate space), so you can get the distance in three dimensions between two transforms by simply subtracting those vectors.
let anchorPosition = anchor.transforms.columns.3
let cameraPosition = camera.transform.columns.3
// here’s a line connecting the two points, which might be useful for other things
let cameraToAnchor = cameraPosition - anchorPosition
// and here’s just the scalar distance
let distance = length(cameraToAnchor)
What you’re doing isn’t working right because you’re subtracting the z-coordinates of each vector. If the two points are different in x, y, and z, just subtracting z doesn’t get you distance.
This one is for scenekit, I'll leave it here though.
let end = node.presentation.worldPosition
let start = sceneView.pointOfView?.worldPosition
let dx = (end?.x)! - (start?.x)!
let dy = (end?.y)! - (start?.y)!
let dz = (end?.z)! - (start?.z)!
let distance = sqrt(pow(dx,2)+pow(dy,2)+pow(dz,2))
With RealityKit there is a slightly different way to do this. If you're using the world tracking configuration, your AnchorEntity object conforms to HasAnchoring which gives you a target. Target is an enum of AnchoringComponent.Target. It has a case .world(let transform). You can compare your world transform to the camera's world transform like this:
if case let AnchoringComponent.Target.world(transform) = yourAnchorEntity.anchoring.target {
let theDistance = distance(transform.columns.3, frame.camera.transform.columns.3)
}
This took me a bit to figure out but I figure others that might be using RealityKit might benefit from this.
As mentioned above by #codeman, this is the right solution:
let distance = simd_distance(YOUR_NODE.simdTransform.columns.3, (sceneView.session.currentFrame?.camera.transform.columns.3)!);
3D distance - You can check these utils,
class ARSceneUtils {
/// return the distance between anchor and camera.
class func distanceBetween(anchor : ARAnchor,AndCamera camera: ARCamera) -> CGFloat {
let anchorPostion = SCNVector3Make(
anchor.transform.columns.3.x,
anchor.transform.columns.3.y,
anchor.transform.columns.3.z
)
let cametaPosition = SCNVector3Make(
camera.transform.columns.3.x,
camera.transform.columns.3.y,
camera.transform.columns.3.z
)
return CGFloat(self.calculateDistance(from: cametaPosition , to: anchorPostion))
}
/// return the distance between 2 vectors.
class func calculateDistance(from: SCNVector3, to: SCNVector3) -> Float {
let x = from.x - to.x
let y = from.y - to.y
let z = from.z - to.z
return sqrtf( (x * x) + (y * y) + (z * z))
}
}
And now you can call:
guard let camera = session.currentFrame?.camera else { return }
let anchor = // you anchor
let distanceAchorAndCamera = ARSceneUtils.distanceBetween(anchor: anchor, AndCamera: camera)
So basically I am looking to choose one of the 4 different coloured balls at random to come into the scene which each have an animation, physics properties and movement & spacing that I have already coded. I am not sure exactly how to make the array then choose at random from the array of the 4 coloured balls so that I have one ball chosen at random to come into the scene.
To make it more clear what I'm asking here's some code (I only use two balls in this code so you don't have to read as much):
var moveandremove = SKAction() < this is in my ballScene.swift
The spawn runBlock is inside didMovetoView
let spawn = SKAction.runBlock({
() in
self.allballs()
})
let delay = SKAction.waitForDuration(2.0)
let SpawnDelay = SKAction.sequence([spawn, delay])
let spawndelayforever = SKAction.repeatActionForever(SpawnDelay)
self.runAction(spawndelayforever)
let distance = CGFloat(brnball.frame.width * 20 + brnball.frame.width)
let moveball = SKAction.moveByX(-distance, y: 0, duration: NSTimeInterval(0.003 * distance))
let removeball = SKAction.removeFromParent()
moveandremove = SKAction.sequence([moveball])
}
func allballs() {
TextureAtlasblk = SKTextureAtlas(named: "blkball")
for i in 1...TextureAtlasblk.textureNames.count{
var Name = "blkball_\(i)"
blkarray.append(SKTexture(imageNamed: Name))
}
blkball = SKSpriteNode(imageNamed: "blkball_1")
blkball.position = CGPoint(x: CGRectGetMidX(self.frame) + 100, y: CGRectGetMidY(self.frame))
blkball.zPosition = 7
blkball.setScale(0.1)
self.addChild(blkball)
blkball.runAction(SKAction.repeatActionForever(SKAction.animateWithTextures(blkarray, timePerFrame: 0.2)))
//brownball
TextureAtlasbrn = SKTextureAtlas(named: "brnball")
for i in 1...TextureAtlasbrn.textureNames.count{
var Name = "brnball_\(i)"
brnarray.append(SKTexture(imageNamed: Name))
}
brnball = SKSpriteNode(imageNamed: "brnball_1")
brnball.position = CGPoint(x: CGRectGetMidX(self.frame) + 50, y: CGRectGetMidY(self.frame))
brnball.zPosition = 7
brnball.setScale(0.1)
self.addChild(brnball)
brnball.runAction(SKAction.repeatActionForever(SKAction.animateWithTextures(brnarray, timePerFrame: 0.2)))
Here is my terrible starting point at trying to make an array to choose from each ball (this is inside my allballs() function):
var ballarray: NSMutableArray = [blkball, brnball, yelball, bluball]
runAction(moveandremove)
I am new to swift and pretty hopeless, would be awesome if someone could help me out :)
Thanks
It's hard for me to find the array that you're talking about in your code. But nevertheless, I can still show you how.
Let's say we have an [Int]:
let ints = [10, 50, 95, 48, 77]
And we want to get a randomly chosen element of that array.
As you may already know, you use the subscript operator with the index of the element to access an element in the array, e.g. ints[2] returns 95. So if you give a random index to the subscript, a random item in the array will be returned!
Let's see how can we generate a random number.
The arc4random_uniform function returns a uniformly distributed random number between 0 and one less the parameter. Note that this function takes a UInt32 as a parameter and the return value is of the same type. So you need to do some casting:
let randomNumber = Int(arc4random_uniform(UInt32(ints.count)))
With randomNumber, we can access a random element in the array:
let randomItem = ints[randomNumber]
Try to apply this technique to your situation.
Here's a generic method to do this as well:
func randomItemInArray<T> (array: [T]) -> T? {
if array.isEmpty {
return nil
}
let randomNumber = Int(arc4random_uniform(UInt32(array.count)))
return array[randomNumber]
}
Note that if the array passed in is empty, it returns nil.
You could make and extension for Array that returns a random element.
extension Array {
func randomElement() -> Element {
let i = Int(arc4random_uniform(UInt32(count - 1)))
return self[i]
}
}
You could take that a step further and allow a function to be applied directly to a random element.
mutating func randomElement(perform: (Element) -> Element) {
let i = Int(arc4random_uniform(UInt32(count - 1)))
self[i] = perform(self[i])
}
You can use this function when using an array of reference types.
func randomElement(perform: (Element) -> ()) {
let i = Int(arc4random_uniform(UInt32(count - 1)))
perform(self[i])
}
I'm trying to add something like UIPopoverController into the barPlot with coreplot 1.5.1 and swift. Like this one Core Plot: How to present popover from a bar selected by the user
So we need to know the point where the selected bar is ,But looks like some functions are different, like plotAreaViewPointForPlotPoint. In 1.5.1, there are two parameters:
And I'm try to find the right way to use it but failed, here is my code:
func barPlot(plot: CPTBarPlot!, barWasSelectedAtRecordIndex idx: UInt, withEvent event: UIEvent!) {
// Remove all the annotations
graphView.hostedGraph.plotAreaFrame.plotArea.removeAllAnnotations()
// Setup a style for the annotation
let hitAnnotationTextStyle = CPTMutableTextStyle.textStyle() as! CPTMutableTextStyle
hitAnnotationTextStyle.color = CPTColor.whiteColor()
hitAnnotationTextStyle.fontSize = 12.0;
hitAnnotationTextStyle.fontName = FONT_HEITI;
// Determine point of symbol in plot coordinates
let anchorPoint = [Int(idx),0]
// Add annotation
// First make a string for the y value
let string = "\(idx),values is：\(mArray.objectAtIndex(Int(idx)))"
// Now add the annotation to the plot area
let textLayer = CPTTextLayer(text: string, style: hitAnnotationTextStyle)
// popview, DxPopover is something like UIPopover Controller in iPhone
var popView = DXPopover()
annotationLabel.text = string
var pointers = [NSDecimal](count: 2, repeatedValue: CPTDecimalFromUnsignedInteger(0))
pointers[0] = CPTDecimalFromUnsignedInteger(idx)
var plotPointer: UnsafeMutablePointer<NSDecimal> = UnsafeMutablePointer<NSDecimal>.alloc(pointers.count)
plotPointer.initializeFrom(pointers)
var popPoint = graphView.hostedGraph.defaultPlotSpace.plotAreaViewPointForPlotPoint(plotPointer, numberOfCoordinates: idx)
popView.showAtPoint(popPoint, popoverPostion: DXPopoverPosition.Down, withContentView: self.annotationView, inView: graphView)
// selectedBarAnnotation = CPTPlotSpaceAnnotation(plotSpace: graphView.hostedGraph.defaultPlotSpace, anchorPlotPoint: anchorPoint)
// selectedBarAnnotation!.contentLayer = textLayer
// selectedBarAnnotation!.displacement = CGPointMake(0.0, -15.0)
// graphView.hostedGraph.plotAreaFrame.plotArea.addAnnotation(selectedBarAnnotation)
}
And it will crush at this line:
var popPoint = graphView.hostedGraph.defaultPlotSpace.plotAreaViewPointForPlotPoint(plotPointer, numberOfCoordinates: idx)
SO, HOW CAN I GET THE RIGHT CGPOINT?
Thanks very much!
=================EDIT===================
I change my codes to this, and can get the right point, Thanks to #Bannings
var popView = DXPopover()
annotationLabel.text = string
var pointers = [NSDecimal](count: 2, repeatedValue: CPTDecimalFromUnsignedInteger(0))
let plotXvalue = self.numberForPlot(plot, field: UInt(CPTScatterPlotFieldX.value), recordIndex: idx)
pointers[0] = CPTDecimalFromFloat(plotXvalue.floatValue)
println("\(CPTDecimalFromUnsignedInteger(idx))")
let plotspace = graphView.hostedGraph.defaultPlotSpace
println("\(plotspace.numberOfCoordinates)")
var popPoint = plotspace.plotAreaViewPointForPlotPoint(&pointers, numberOfCoordinates: plotspace.numberOfCoordinates)
popView.showAtPoint(popPoint, popoverPostion: DXPopoverPosition.Down, withContentView: self.annotationView, inView: graphView)
Try this:
var popPoint = graphView.hostedGraph.defaultPlotSpace.plotAreaViewPointForPlotPoint(&pointers, numberOfCoordinates: idx)