Hi, I want to begin by saying thank you Apple for making the Spatial framework! Please add a million more features ;-) I'm using the following code to make an object "look at" another point, but at a particular rotation the object "flips" its rotations. See a video here: https://www.dropbox.com/s/5irxt0gxou4c2j6/QuaternionFlip.mov?dl=0 I shake the mouse cursor when it happens to make it obvious to you. import Spatial let lookAtRotation = Rotation3D(eye: Point3D(position), target: Point3D(x: 0, y: 0, z: 0), up: Vector3D(x: 0, y: 1, z: 0)) myObj.quaternion = lookAtRotation.quaternion So my question is why is this happening, and how can I fix it? thx

Hi, I'm trying to convert my SceneKit code into pure Metal/MetalKit and I feel confused about this code and how I should rewrite it. I've made the code simple for this case with some pseudocode. The part where it says "SceneKit magic" is where I feel lost. The SCNNode is just an empty placeholder just as it is – and it works for the calculations it is doing inside. Any help and pointers are much appreciated :-) class Scene { let ball = Ball() let scnNode = SCNNode() var quaternionAngleVelocity = float2(0, 0) func update() { // pseudocode, the user press the up key quaternionAngleVelocity.x -= 3 // pseudocode, the user press the down key quaternionAngleVelocity.x += 3 // pseudocode, the user press the left key quaternionAngleVelocity.y -= 3 // pseudocode, the user press the right key quaternionAngleVelocity.y += 3 ... // apply friction quaternionAngleVelocity *= (1 - 0.05) // i.e. decrease with 5% // rotate let newQuaternionAxisX = simd_quatf(angle: quaternionAngleVelocity.x.degreesToRadians, axis: simd_float3(x: 1, y: 0, z: 0)) let newQuaternionAxisY = simd_quatf(angle: quaternionAngleVelocity.y.degreesToRadians, axis: simd_float3(x: 0, y: 1, z: 0)) let finalQuaternion = simd_normalize(newQuaternionAxisX * newQuaternionAxisY) // SceneKit magic…? let matrix4 = SCNMatrix4Mult(scnNode.worldTransform, SCNMatrix4(simd_float4x4(finalQuaternion))) scnNode.transform = matrix4 ball.quaternion = scnNode.simdWorldOrientation } } class Ball { var position: float3 = [0, 0, 0] var rotation: float3 = [0, 0, 0] { didSet { let rotationMatrix = float4x4(rotation: rotation) quaternion = simd_quatf(rotationMatrix) } } var scale: float3 = [1, 1, 1] var forwardVector: float3 { return normalize([sin(rotation.y), 0, cos(rotation.y)]) } var rightVector: float3 { return [forwardVector.z, forwardVector.y, -forwardVector.x] } var upVector: float3 { return [0, forwardVector.z, 0] } var quaternion = simd_quatf() var modelMatrix: float4x4 { let translateMatrix = float4x4(translation: position) // let rotateMatrix = float4x4(rotation: rotation) let rotateMatrix = float4x4(quaternion) let scaleMatrix = float4x4(scaling: scale) return (translateMatrix * rotateMatrix * scaleMatrix) } var worldTransform: float4x4 { return modelMatrix } }

I get Error Domain=kCLErrorDomain Code=1 "(null)" in the Xcode console when a start to update for location. This does not happen in the example app, so I'm wondering what I might have done wrong?

Be aware, there are many errors / non-existing API's etc. in this session. This is yet the worst session I've seen in this years WWDC. Sorry but I have to be honest.

Watching https://developer.apple.com/wwdc20/10644 Using Swift on AWS Lambda with Xcode. When I call http://127.0.0.1:7000/invoke I get Status: 405 Method Not Allowed? in the browser. And my breakpoint does not hit, no message in Xcode either. Did anyone get this to work?

I'm using Xcode 12. I have set the ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME to "AccentColor", and created a Color Set named "AccentColor". When run I still see the default system blue color as the tint. I don't understand why this does not work. I've done exactly as it is when I create a new iOS project from scratch. This does not seem to work in my existing project.