I created an scn file using Xcode (as you can see below), where there are two nodes (a sphere and a platform). I set up the position of the sphere:
I used a class which creates a node platform, which you can resize and move:
Screenshot
After pressing a button it places my scn file instead of that platform (with the same scale, position, and orientation) The problem is I don't know how to get sphere's position from the scene view.
let sphere = SCNNode()
self.scene.parent!.enumerateChildNodes { (node, _) in
if node.name == "sphere" {
sphere = node
sphere.position = node.position
print(sphere.position)
}
}
Using that code it always prints the position that I set up in the scn file (as you can see above), but I want the real position of it in the view.
ScreenShot
With sphere.position you will get the position of sphere relative to its parent node. If you want the position in the scene you have to use sphere.worldPosition.
Related
It's so confusing to me, would be grateful if anyone help me on it.
I have a shadow plane to show the shadow below the AR object. I read some article that they define this shadow in viewDidLoadand add it as the child bode to sceneView.scene. The question is, it should be defined only once for the floor surface?
for instance, I can add the shadow plane to renderer(_:didAdd:for:), it call it once when a new surface is detected. That is so cool for me. But the position of the shadow plane should be changed as well? can someone explain it to me that where it should be defined and wehere/when it should be updated?
here how I define the shadow plane
private func addShadowPlane(node: SCNNode, planeAnchor: ARPlaneAnchor) {
let anchorX = planeAnchor.center.x
let anchorY: planeAnchor.center.y
let anchorZ = planeAnchor.center.z
let floor = SCNFloor()
let floorNode = SCNNode(geometry: floor)
floorNode.position = SCNVector3(anchorX, anchorY, anchorZ)
floor.length = CGFloat(planeAnchor.extent.z)
floor.width = CGFloat(planeAnchor.extent.x)
floor.reflectivity = 0
floor.materials = [shadowMaterialStandard()]
node.addChildNode(floorNode)
}
func shadowMaterialStandard() -> SCNMaterial {
let material = SCNMaterial()
material.lightingModel = .physicallyBased
material.writesToDepthBuffer = true
material.readsFromDepthBuffer = true
material.colorBufferWriteMask = []
return material
}
The issue you might run into is: Do you want one single shadow plane in a kind of initial defined position and then remains there (or can be repositioned). Or do you want a lots of shadow planes, like on any surface captured with the ARKit? The problem might be, that all those planes will not be exact and accurate to the surfaces on top they are created (just more or less). You can make more accurate shapes for surfaces, but they are built up in an ongoing process and need more time to complete (imagine you scan a table by walking around). I also did some ARApps with Shadow planes. I usually create one single shadow plane (like 20x20 meters) on my request using a focus square. I fetch the worldPosition from the focus square, then I add a plane to that location using Scenekit (and not the Renderer for plane anchors). Keep in mind, there are many ways to do this. There is no best way.
Try to study this Apple Sample App for more information on placing objects, casting shadows etc:
https://developer.apple.com/documentation/arkit/environmental_analysis/placing_objects_and_handling_3d_interaction
as background lets assume I have a map- literally a road map being rendered inside my SKScene. Roads are represented by SKShapenodes with path set to an array of CGPoints. I want the user to be able to zoom in/out so I created a camera node:
var cam: SKCameraNode = SKCameraNode()
and as the user wants to zoom in/out by scrolling on the trackpad:
let zoomInAction = SKAction.scale(to: CGFloat(scale), duration: 0.0)
camera?.run(zoomInAction)
This works great however I have an additional complexity which I'm not sure how to handle. I want some nodes (for examples road name labels, icons, map legend) to be exempt from scaling- such that as a user zooms in/out the road name label remains the same size while the road shape scales proportionally.
Not sure how to handle this? Can I have a hierarchy of scenes so one layer scales and the other doesnt scale? Can that be achieved by attaching the camera node to the "scalable" layer? Any help appreciated!
Here is the case. If you want the node scale won't change with camera, just add the node to the tree of camera. Don't forget add cameraNode to scene, otherwise, those nodes connected to camera won't be rendered.
In the following, label is rendered via camera and won't change scale.
let label = SKLabelNode.init(text: "GFFFGGG")
label.fontSize = 30
label.fontColor = UIColor.black
label.name = "cool"
label.zPosition = 100
let camera = SKCameraNode()
camera.addChild(label)
scene.addChild(camera)
scene.camera = camera
camera.position = CGPoint.init(x: 0, y: 0)
camera.xScale = 2.0
If you have nodes connecting to scene before,
you may remove the node from parent and then add to camera.
If using a function to batch handling them should not be as hard as thought.
Maybe not necessary:
You may transfer them to cameraNode tree via camera.convert(point: , from:) etc.
I want to put the red node right behind the blue node even after i change the position of iPhone.
(Please refer to the diagram)
When I start my AR App and tap the center of the screen to add the blue node, I get the blue node x,y,z axis and set the z axis of the red node a little bit further away. On this scenario my app behaves the way i expected.
The problem is when I rotate the iPhone, tap the screen to add the blue node, the red node seemed to be at the same depth like the initial state.
What i expected to have is when I add a blue node, always put the red node behind it (the blue node should always cover the red node the moment I add it)
Do anyone know how to do it?
I have this code to make the nodes always face the camera when i add them. but the position in space is kinda not the one I expected
//TAP THE SCREEN
let worldTransform = hitTestResultsWithFeaturePoint.worldTransform
let hitTransform = SCNMatrix4(worldTransform)
let hitVector = SCNVector3Make(hitTransform.m41, hitTransform.m42, hitTransform.m43)
let rotate = simd_float4x4(SCNMatrix4MakeRotation(sceneView.session.currentFrame!.camera.eulerAngles.y, 0, 1, 0))
let rotateTransform = simd_mul(worldTransform, rotate)
//ADD THE BLUE NODE
let bluenode = SCNNode()
bluenode.transform = SCNMatrix4(rotateTransform)
bluenode.position = SCNVector3(hitVector.x, hitVector.y, hitVector.z)
//ADD THE RED NODE BEHIND THE BLUE NODE
let rednode = SCNNode()
rednode.transform = SCNMatrix4(rotateTransform)
rednode.position = SCNVector3(hitVector.x, hitVector.y, hitVector.z - 0.05)
Adding the red node as a child of the blue one with coordinates to (0.0,0.0,-0.05) and then making the blue node face the camera with "SCNBillboardConstraint" should do the trick
I really need to know how to lock the x axis of an SKSpriteNode and its physicsBody. I need to keep the SKSpriteNode dynamic and affectedByGravity. The node is on a slope, so this is why it's x axis is moved due to gravity. However, I don't want the x axis of this SKSpriteNode to move due to gravity. Is there a way to lock the x axis in order to achieve this?
Thanks for any help :D
Edit: I have tried to apply a constraint to the x value like this:
let xConstraint = SKConstraint.positionX(SKRange(constantValue: 195))
node.constraints?.append(xConstraint)
However this doesn't work and I'm not sure why and how to fix it. Anyone know of a solution?
Edit 2: SKPhysicsJointPin is actually looking more promising. In the comments of the first response/answer to this question, I have been trying to figure how to properly use it in my situation.
An example of my code:
let node = SKSpriteNode(imageNamed: "node")
enum collisionType: UInt32 {
case node = 1
case ground = 2
case other = 4 //the other node is unrelated to the ground and node
}
class GameScene: SKScene, SKPhysicsContactDelegate {
override func didMove(to view: SKView) {
//Setup node physicsBody
node.physicsBody = SKPhysicsBody(rectangleOf: node.size)
node.physicsBody?.categoryBitMask = collisionType.node.rawValue
node.physicsBody?.collisionBitMask = //[other node that isn't the ground or the node]
node.physicsBody?.contactTestBitMask = //[other node that isn't the ground or the node]
node.physicsBody?.isDynamic = true
node.physicsBody?.affectedByGravity = true
addChild(node)
//Physics Setup
physicsWorld.contactDelegate = self
}
The node is on top of the ground, and the ground is composed of various SKSpriteNode lines that have a volumeBased physicsBody. The ground keeps adding new lines at the front, and removing the ones at the back, and changing the x value of each line by a negative (so the ground appears to moving - this process is performed in an SKAction). These lines (the parts of the ground) are on an angle which is why the node's x axis moves. I want the node to always be at the front of the ground (e.g. always on top of the newly created line). Currently, setting the position of the node like this locks the x axis (solving my issue):
override func didSimulatePhysics() {
//Manage node position
node.position.x = 195
node.position.y = CGFloat([yPosition of the first line of the ground - the yPosition keeps changing])
}
Note: ^This^ function is inside the GameScene class
The x axis actually stays the same like this. However, the issue is that now the physicsBody of the node is lower than the centre of the node (which didn't happen before).
A node's constraints property is nil by default. You'll need to create an array of one or more constraints and assign it to the property. For example
let xConstraint = SKConstraint.positionX(SKRange(constantValue: 195))
node.constraints = [xConstraint]
Update
You may want to use a camera node instead of moving the ground in the scene. With a camera node, you move the main character and the camera instead of the ground.
I think you could set the linearDamping property to 0.0
The linearDamping is a property that reduces the body’s linear velocity.
This property is used to simulate fluid or air friction forces on the
body. The property must be a value between 0.0 and 1.0. The default
value is 0.1. If the value is 0.0, no linear damping is applied to the
object.
You should pay attention also to the other forces applied to your SKSpriteNode. The gravitational force applied by the physics world for example where dx value, as you request , should be setted to 0.0:
CGVector(dx:0.0, dy:-4.9)
Remember also that when you apply other forces vectors like velocity you should maintain the dx property to 0.0 as constant if you want to block the x axis.
You could find more details to the official docs
Update (after your details to the comments below):
You could also anchored your sprite to the ground with an SKPhysicsJoint (I don't know your project so this is only for example):
var myJoint = SKPhysicsJointPin.joint(withBodyA: yourSprite.physicsBody!, bodyB: yourGround.physicsBody!, anchor: CGPoint(x: yourSprite.frame.minX, y: yourGround.frame.minY))
self.physicsWorld.add(myJoint)
You can work with the anchor property to create a good joint as you wish or adding more joints.
I'm currently working in Xcode 8, using Swift 3 and the new SKTileMapNode from SpritKit to make a 2D dungeon crawler type of game.
I'm have trouble getting GKObstacleGraph to work with the tilemap. Please help!
I tried to loop through all the tiles within the obstacle layer of the tilemap and create a polygon for each tile and store it in the GKObstacleGraph. Each tile in obstacle layer is a wall tile. The map looks like some type of dungeon crawler, so the wall is all over the places.
I have something like below:
for row in 0..<tileMapNode.numberOfRows {
for column in 0..<tileMapNode.numberOfColumns {
let tile = tileMapNode.tileDefinition(atColumn: column, row: row)
let tileCenter = tileMapName.centerOfTile(atColumn: column, row: row)
//find 4 corners of each tile from its center
let bottomLeft = float2(CGPointMake(tileCenter.x - tile.size.width/2, tileCenter.y - tile.size.height/2))
let bottomRight = float2(CGPointMake((tileCenter.x - tile.size.width/2, tileCenter.y + tile.size.height/2))
let topRight = float2(CGPointMake((tileCenter.x + tile.size.width/2, tileCenter.y + tile.size.height/2))
let topLeft = float2(CGPointMake((tileCenter.x - tile.size.width/2, tileCenter.y + tile.size.height/2))
var vertices = [topLeft , bottomLeft , bottomRight , topRight ]
let obstacle = GKPolygonObstacle(points: &vertices, count: 4)
obstacleGraph.add(obstacle)
}
}
However, when i run the app it shows that there are over 80000 nodes, way too many pathfinding pathes.
Any help would be appreciated.
I'm not certain that GKObstacleGraph is the right choice of graph here. According to the GameplayKit documentation:
For example, you can design a level with the SpriteKit Scene Editor in Xcode and use physics bodies to mark regions that the player (or other game entities) cannot pass through, then use the obstaclesFromNodePhysicsBodies: method to generate GKPolygonObstacle objects marking impassable regions.
The function obstaclesFromNodePhysicsBodies is used like this to extract obstacles and create the graph;
let obstacles = SKNode.obstaclesFromNodePhysicsBodies(self.children)
graph = GKObstacleGraph(obstacles: obstacles, bufferRadius: 0.0)
For a SKTilemapNode representing a cartesian grid, the GKGridGraph seems the likely choice.