tower world gen

Sources/Voxelotl/Generator/TerrorTowerGenerator.swift

@@ -0,0 +1,33 @@
+import simd
+
+struct TerrorTowerGenerator: WorldGenerator {
+  var noise1: LayeredNoise<ImprovedPerlin<Float>>!
+  var noise2: LayeredNoise<SimplexNoise<Float>>!
+
+  public mutating func reset(seed: UInt64) {
+    var random = Xoroshiro128PlusPlus(state: SplitMix64.createState(seed: seed))
+    self.noise1 = LayeredNoise(random: &random, octaves: 4, frequency: 0.05, amplitude: 1.1)
+    self.noise2 = LayeredNoise(random: &random, octaves: 3, frequency: 0.1, amplitude: 0.5)
+  }
+
+  public func makeChunk(id chunkID: SIMD3<Int>) -> Chunk {
+    let chunkOrigin = chunkID &<< Chunk.shift
+    var chunk = Chunk(position: chunkOrigin)
+    chunk.fill(allBy: { position in
+      let fpos = SIMD3<Float>(position)
+        let threshold: Float = 0.6
+        let gradient = simd_length(fpos.xz) / 14.0
+        let value = self.noise1.get(fpos) - 0.25
+      return if gradient + value < threshold {
+        .solid(.init(
+          hue: ((fpos.x * 0.5 + fpos.y) / 30.0) * 360.0,
+          saturation: 0.2 + noise2.get(fpos) * 0.2,
+          value: 0.75 + noise2.get(SIMD4(fpos, 1) * 0.25)
+        ).linear)
+      } else {
+        .air
+      }
+    })
+    return chunk
+  }
+}