simd_float4x4 Columns - swift

Question

I want to translate a plane without rotating the image. For any reason my image is being rotated.
var translation = matrix_identity_float4x4
translation.colum = -0.2
let transform = simd_mul(currentFrame.camera.transform, translation)
planeNode.simdWorldTransform = matrix_multiply(currentFrame.camera.transform, translation)
Also, I notice that matrix_identity_float4x4 contains 4 columns but the documentation is not available.
Why 4 columns? Are there the frame of the plane?

Answer 1

The simplest way to do it is to use the following code for positioning:
let planeNode = SCNNode()
planeNode.geometry = SCNPlane(width: 20, height: 20)
// At first we need to rotate a plane about its x axis in radians:
planeNode.rotation = SCNVector4(1, 0, 0, -Double.pi/2)
planeNode.geometry?.materials.first?.diffuse.contents = UIColor.red
planeNode.position.x = 10
planeNode.position.z = 10
// planeNode.position = SCNVector3(x: 10, y: 0, z: 10)
scene.rootNode.addChildNode(planeNode)
or this way:
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
cameraNode.position = SCNVector3(x: 0, y: 0, z: 15)
scene.rootNode.addChildNode(cameraNode)
let planeNode = SCNNode()
planeNode.geometry = SCNPlane(width: 20, height: 20)
planeNode.rotation = SCNVector4(1, 0, 0, -Double.pi/2)
planeNode.geometry?.materials.first?.diffuse.contents = UIColor.red
let distance: Float = 50
planeNode.simdPosition = cameraNode.simdWorldFront * distance // -Z axis
planeNode.simdPosition = cameraNode.simdWorldRight * distance // +X axis
scene.rootNode.addChildNode(planeNode)
If you wanna know more about matrices used in ARKit and SceneKit frameworks just look at Figure 1-8 Matrix configurations for common transformations.
Hope this helps.