是否可以从字符串构造simd_float4x4,例如:我有一个存储simd_float4x4.debugdescription值的字符串?
答案 0 :(得分:2)
这里是extension
的{{1}},其中添加了 failable simd_float4x4
,该错误接受调试描述并创建init
。这是失败 simd_float4x4
,因为字符串可能格式错误。
init
测试
import simd
extension simd_float4x4 {
init?(_ string: String) {
let prefix = "simd_float4x4"
guard string.hasPrefix(prefix) else { return nil }
let csv = string.dropFirst(prefix.count).components(separatedBy: ",")
let filtered = csv.map { $0.filter { Array("-01234567890.").contains($0) } }
let floats = filtered.compactMap(Float.init)
guard floats.count == 16 else { return nil }
let f0 = float4(Array(floats[0...3]))
let f1 = float4(Array(floats[4...7]))
let f2 = float4(Array(floats[8...11]))
let f3 = float4(Array(floats[12...15]))
self = simd_float4x4(f0, f1, f2, f3)
}
}
输出
let col0 = float4(0.1, 0.2, 0.3, 0.4) let col1 = float4(1.1, 1.2, 1.3, 1.4) let col2 = float4(2.1, 2.2, 2.3, 2.4) let col3 = float4(-3.1, -3.2, -3.3, -3.4) var x = simd_float4x4(col0, col1, col2, col3) print(x) let xDesc = x.debugDescription if let y = simd_float4x4(xDesc) { print(y) }