tower world gen

Sources/Voxelotl/Noise/LayeredNoise.swift

@@ -0,0 +1,53 @@
+
+public struct LayeredNoise<Generator: CoherentNoise> {
+  public typealias Scalar = Generator.Scalar
+
+  public let octaves: Int
+  public let frequency: Scalar
+  public let amplitude: Scalar
+
+  private let _generators: [Generator]
+
+  init(octaves: Int, frequency: Scalar, amplitude: Scalar) {
+    self.octaves   = octaves
+    self.frequency = frequency
+    self.amplitude = amplitude
+    self._generators = Array(repeating: .init(), count: octaves)
+  }
+}
+
+public extension LayeredNoise where Generator: CoherentNoiseRandomInit {
+  init<Random: RandomProvider>(random: inout Random, octaves: Int, frequency: Scalar, amplitude: Scalar) {
+    self.octaves   = octaves
+    self.frequency = frequency
+    self.amplitude = amplitude
+    self._generators = Array(repeating: Generator(random: &random), count: octaves)
+  }
+}
+
+public extension LayeredNoise where Generator: CoherentNoise2D {
+  func get(_ point: SIMD2<Scalar>) -> Scalar {
+    zip(self._generators, 0..<self.octaves).map { layer, term in
+      let mul = Scalar(1 + term)
+      return layer.get(point * frequency * mul) / mul
+    }.reduce(0) { $0 + $1 } * amplitude
+  }
+}
+
+public extension LayeredNoise where Generator: CoherentNoise3D {
+  func get(_ point: SIMD3<Scalar>) -> Scalar {
+    zip(self._generators, 0..<self.octaves).map { layer, term in
+      let mul = Scalar(1 + term)
+      return layer.get(point * frequency * mul) / mul
+    }.reduce(0) { $0 + $1 } * amplitude
+  }
+}
+
+public extension LayeredNoise where Generator: CoherentNoise4D {
+  func get(_ point: SIMD4<Scalar>) -> Scalar {
+    zip(self._generators, 0..<self.octaves).map { layer, term in
+      let mul = Scalar(1 + term)
+      return layer.get(point * frequency * mul) / mul
+    }.reduce(0) { $0 + $1 } * amplitude
+  }
+}