In iOS/Swift, what module is MatrixHelper a part of? - ios

Question

I'm trying to follow some sample code https://medium.com/#yatchoi/getting-started-with-arkit-real-life-waypoints-1707e3cb1da2 below and I'm getting unresolved identifier 'MatrixHelper'
let translationMatrix = MatrixHelper.translate(
x: 0,
y: 0,
z: distance * -1
)
// Rotation matrix theta degrees
let rotationMatrix = MatrixHelper.rotateAboutY(
degrees: bearing * -1
)
What library or package do I need to import to get MatrixHelper - some Math package? I googled the docs but couldn't find anything.

Answer 1

I think he just wrote a custom class to wrap the functions provided by GLKit.
He named that class MatrixHelper.
With MatrixHelper.rotateAboutY() he is calling something like:
GLKMatrix4 GLKMatrix4Rotate(GLKMatrix4 matrix, float radians, float x, float y, float z);
So the package used in MatrixHelper is GLKit and to be more precise GLKMatrix4
https://developer.apple.com/documentation/glkit/glkmatrix4-pce

Answer 2

You can avoid using MatrixHelper (also GLKit), use simd, it is simple. The methods would look the following way:
func getTranslationMatrix(tx: Float, ty: Float, tz: Float) -> simd_float4x4 {
var translationMatrix = matrix_identity_float4x4
translationMatrix.columns.3 = simd_float4(tx, ty, tz, 1)
return translationMatrix
}
func getRotationYMatrix(angle: Float) -> simd_float3x3 {
let rows = [
simd_float3(cos(angle), 0, -sin(angle)),
simd_float3(0, 1, 0),
simd_float3(-sin(angle), 0, cos(angle))
]
return float3x3(rows: rows)
}
Or more specific the translation matrix:
func getTranslationZMatrix(tz: Float) -> simd_float4x4 {
var translationMatrix = matrix_identity_float4x4
translationMatrix.columns.3.z = tz
return translationMatrix
}
Then the code would look like:
func getTransformGiven(currentLocation: CLLocation) -> matrix_float4x4 {
let bearing = bearingBetween(
startLocation: currentLocation,
endLocation: location
)
let distance: Float = 5
let originTransform = matrix_identity_float4x4
// Create a transform with a translation of 5meter away
// let translationMatrix = MatrixHelper.translate(
// x: 0,
// y: 0,
// z: distance * -1
// )
let translationMatrix = getTranslationZMatrix(tz: distance * -1)
// Rotation matrix theta degrees
// let rotationMatrix = MatrixHelper.rotateAboutY(
// degrees: bearing * -1
// )
let rotationMatrix = getRotationYMatrix(angle: Float(bearing * 180 / Double.pi))
var transformMatrix = simd_mul(rotationMatrix, translationMatrix)
return simd_mul(originTransform, transformMatrix)
}