Ok, what I am trying to do is create physics body/colliding boundaries for my character, my SCNNode, in my SceneKit game Im building with ARKit. This is so my node cannot move out of the user's vision/go so far away that it isn't visible as it is currently doing. My SCNNode is moved by user input, so I need to make "world boundaries" while ARKit still doesn't have vertical wall detection
I know you can place an object some set distance ahead of you in the real world as stated here Understand coordinate spaces in ARKit
and I have done that with this, just making a box with physics body here -
let box = SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0) //change to be VERY TALL - need to make it a giant room
node.physicsBody = SCNPhysicsBody(type: SCNPhysicsBodyType.static, shape: nil)
box.firstMaterial?.diffuse.contents = UIColor.red
box.firstMaterial?.isDoubleSided = true
node = SCNNode(geometry: box)
node.position = SCNVector3(view.pointOfView.simdWorldFront + float3(0, 0, -0.5)) //random distance ahead
And this works, and I could add it as a child node of camera so it moves as user moves, but I don't think Im doing this correctly.
Essentially I need 4 walls to box the user/SCNNode in (corral the character) that are infinitely high, and at the VERY edge of the horizontal plane that the user can see. Really I don't know what this distance should be in the x plane:
+ float3(0, 0, -0.5)
How would you create AR boundaries like this?
Related
I'm trying to render objects further away than 1000.
let box = SCNBox(width: 500, height: 500, length: 500, chamferRadius: 0)
let boxNode = SCNNode(geometry: box)
boxNode.position = SCNVector3(0, 0, -2000)
sceneView.scene.rootNode.addChildNode(boxNode)
From this this answer I know that ARKit directly sets SCNCamera's projectionTransform. So is there anyway I change this projectionTransform in order to render objects further away?
In ARKit | SceneKit app, if a distance from ARCamera to 3D model is greater than 1000 meters SceneKit's shader violently begins flickering, and approximately at 1600 meters model disappears completely.
ARCamera doesn't render application's 3D content. This shader's artifact is SceneKit's rendering engine issue. So, you have nothing to do with that at the moment.
Blocks just crumble apart.
How can this problem be solved?
Initializing blocks:
var boxNode = SCNNode(geometry: SCNBox(width: 0.75, height: 0.15, length: 0.25, chamferRadius: 0))
boxNode.position = SCNVector3(x: x1, y: y, z: z1)
boxNode.geometry?.firstMaterial = SCNMaterial()
boxNode.geometry?.firstMaterial?.diffuse.contents = UIImage(named: "wood.jpg")
boxNode.physicsBody = SCNPhysicsBody(type: .dynamic, shape: nil)
boxNode.eulerAngles.y = Float(Double.pi / 2) * rotation
boxNode.physicsBody?.friction = 1
boxNode.physicsBody?.mass = 0.5
boxNode.physicsBody?.angularDamping = 1.0
boxNode.physicsBody?.damping = 1
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full code
I won't be able to tell you how to fix it as I have the exact same problem which I wasn't able to solve. However, as I played around I figured out a couple of things (which you may find useful):
The same problem hasn't happened to me in pure SceneKit, hence I think it's a bug in ARKit
Node with physics has to be added to the rootNode of the scene, otherwise odd stuff happens (elements passing through each other, gravity behaving in an inconsistent way)
If you pass nil as shape parameter, SceneKit will figure bounding box based on the geometry of the node. This hasn't worked properly for me so what I've done (using SceneKit editor) was to duplicate the geometry and then set it as a custom shape for the bounding box (have a look at the attached image)
Overall I've found physics simulation in SceneKit when used with ARKit to be extremely buggy and I spent a lot of time "tricking" it into working more-or-less how I wanted it to work.
So,
I have the exact position I want to place the node at. If I test things with a sphere geometry I can place spheres in the world by telling the node:
node.simdPosition = position
(I provide the "position" as an input to the function).
That successfully places the object in the world exactly where I want it to go.
What I really want to do is placing a plane:
let plane = SCNPlane(width: 0.2, height: 0.3)
plane.cornerRadius = plane.width / 10
plane.firstMaterial?.diffuse.contents = UIColor.red
plane.firstMaterial?.specular.contents = UIColor.white
let node = SCNNode(geometry: plane)
Then telling it to be placed at the "position":
node.simdPosition = position
All this works with the plane as well. What I have problems with is the angle:
I want to tell the plane's node to be placed with a given "angle" (around Y) offset to the camera. I tried this but it's not working:
node.rotation = SCNVector4Make(0, 1, 0, currentFrame.camera.eulerAngles.z - angle)
So then, the question is, how can a node be placed at a certain position and at the moment it gets placed in the world, also have a certain Y angle offset from the perpendicular to the camera?
I was using the wrong Euler angle... (z)
This made it work:
node.eulerAngles = SCNVector3Make(0, cameraEulerAngles.y - Float(0.7), 0)
Generally what I'm trying to achieve: we have map data that historically was all 2D, and the coordinate system we use is the origin point (0,0) at the top left, positive x goes right, positive y goes down. We have now added 3D data by adding a z axis, positive z coming out of the screen towards you (think top-down map view). This is a left handed coordinate system, but SceneKit is a right handed coordinate system. I would like to apply some transform at the top level of my SceneKit Scene that will convert the Scene into a left handed coordinate system such that I can modify/position/add nodes to the scene in terms of our custom mapping coordinate system and things will just work.
So far I have this:
let scene = SCNScene()
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
cameraNode.scale = SCNVector3(1,-1,1)
scene.rootNode.addChildNode(cameraNode)
This achieves exactly what I want, but has one big problem. It inverts all of the geometry faces, so my geometry's disappear unless I change their material's cullMode:
let mapLength = 1000 //max X axis
let mapWidth = 800 //max Y axis
let mapHeight = 100 //max Z axis
cameraNode.position = SCNVector3(mapLength / 2, mapWidth / 2, 2000)
let mapPlane = SCNNode()
mapPlane.position = SCNVector3(mapLength / 2, mapWidth / 2, 0)
mapPlane.geometry = SCNPlane(width: mapLength, height: mapWidth)
mapPlane.geometry?.firstMaterial?.diffuse.contents = UIColor.blackColor()
scene.rootNode.addChildNode(mapPlane)
mapPlane doesn't show at all! You have to rotate the camera to the underside of mapPlane in order to see it. You can easily fix this by adding a single line:
mapPlane.geometry?.firstMaterial?.cullMode = .Front
But I don't want to have to change the cullMode for every geometry/material. Is there a way to achieve this without requiring extra code at each geometry/material? Some transform that would invert the geometry face normals for all child nodes of rootNode? Ideally this would be achieved entirely by settings on the actual Scene, or by transforms on rootNode or the camera.
I've been playing with the SCNNode object for a while now and I'm lost with the Pivot. How can I change the pivot of a SCNNode (SCNBox as a bar) and place the pivot on one of the edge of the bar?
A node's pivot is a transformation matrix, the inverse of which is applied to the node before its transform property takes effect. For example, take a look at this bit from the default SceneKit Game template in Xcode:
let boxNode = SCNNode()
boxNode.geometry = SCNBox(width: 1, height: 1, length: 1, chamferRadius: 0.02)
If you set the boxNode's position, that point corresponds to the center of the cube, and if you rotate it (as the template does in an animation), it spins around its center.
To change the anchor point, set the pivot to a translation transform:
boxNode.pivot = SCNMatrix4MakeTranslation(0.5, 0.5, 0.5)
Now, when you set the position that point corresponds to the top-right-front corner of the cube, and when you rotate the cube it spins around that corner.
More generally, a pivot transforms the contents of a node relative to the node's own transform. Suppose you wanted to model the precession of the Earth's axis of rotation. You could do this by creating two animations: one that animates pivot to spin the node around its own Y axis, and another that animates rotation to move that axis relative to the space containing the node.
On the pivot topic:
Just in case you do not have dimensions for your geometry/node something like this might help (especially for SCNText).
var minVec = SCNVector3Zero
var maxVec = SCNVector3Zero
if node.getBoundingBoxMin(&minVec, max: &maxVec) {
let bound = SCNVector3(x: maxVec.x + minVec.x,
y: maxVec.y + minVec.y,
z: maxVec.z + minVec.z)
node.pivot = SCNMatrix4MakeTranslation(bound.x / 2,
bound.y / 2,
bound.z / 2)
}