UPDATE: This turned out to be a case of user error. The camera in the SceneKit scene was having the projection matrix overwritten by the projection matrix of the ARKit frame camera in order to keep in sync (we can't use ARSCNView for our needs). However, overwriting the projection matrix changed the near/far which meant the shadows weren't renderered correctly. Using the alternative method: node.camera.projectionTransform = SCNMatrix4(frame.camera.projectionMatrix(for: .landscapeRight, viewportSize: CGSize(width: width, height: height), zNear: 0.1, zFar: 1000))

In fact, this override isn't even giving me the geometry now... I've clearly not used the base clone() correctly language override func clone() - Self { super.clone() return self }

Thank you gchiste, I really appreciate the help. I've created a feedback report as requested. FB9077227

Well... it works if I split uniform float2 worldDimensions; into the more verbose uniform float worldX; uniform float worldY; Which is very annoying. Looking inside the <simd/simd.h> it looks empty? Like all these structs in <simd/vector_types.h> have been taken out??

Okay it looks like things have changed a bit, and a little reading of the original instructions at: https://developer.apple.com/documentation/scenekit/scnshadable#1654834 have cleared things up for me. In short, my float2 should be described as: #pragma arguments float2 worldDimensions; and after that the #pragma body #pragma transparent The shader now works fine again. Also, the SIMD files are presumably empty because they are deprecated in favor of just using the float2, float4 Metal types directly.