High-performance Animatable Vector for SwiftUI

AnimatableVector.swift

import SwiftUI
import enum Accelerate.vDSP

struct AnimatableVector: VectorArithmetic {
    static var zero = AnimatableVector(values: [0.0])

    static func + (lhs: AnimatableVector, rhs: AnimatableVector) -> AnimatableVector {
        let count = min(lhs.values.count, rhs.values.count)
        return AnimatableVector(values: vDSP.add(lhs.values[0..<count], rhs.values[0..<count]))
    }

    static func += (lhs: inout AnimatableVector, rhs: AnimatableVector) {
        let count = min(lhs.values.count, rhs.values.count)
        vDSP.add(lhs.values[0..<count], rhs.values[0..<count], result: &lhs.values[0..<count])
    }

    static func - (lhs: AnimatableVector, rhs: AnimatableVector) -> AnimatableVector {
        let count = min(lhs.values.count, rhs.values.count)
        return AnimatableVector(values: vDSP.subtract(lhs.values[0..<count], rhs.values[0..<count]))
    }

    static func -= (lhs: inout AnimatableVector, rhs: AnimatableVector) {
        let count = min(lhs.values.count, rhs.values.count)
        vDSP.subtract(lhs.values[0..<count], rhs.values[0..<count], result: &lhs.values[0..<count])
    }

    var values: [Double]

    mutating func scale(by rhs: Double) {
        vDSP.multiply(rhs, values, result: &values)
    }

    var magnitudeSquared: Double {
        vDSP.sum(vDSP.multiply(values, values))
    }
}

I just noticed that the AnimatableVector code in the swiftwithmajid.com article includes this code:

mutating func scale(by rhs: Double) {
        values = vDSP.multiply(rhs, values)
}

while this gist makes a small change:

mutating func scale(by rhs: Double) {
        vDSP.multiply(rhs, values, result: &values)
}

However, even when using the code from the gist, the animation issue with the .spring() animation that I described above remains. 🤷‍♂️

I has same situation with .spring() animation. Spending whole day with this. Tks to ur comment. Now know why.

I solved this more delicately.

I reinitiated "static var zero" in AnimatableVector before I initiate the View's vector property.

AnimatableVector.zero = AnimatableVector(values: [0.0, 0.0, 0.0, 0.0])