From 76b61c49aebe2b91fc29f8f2a5436fb3c4928e99 Mon Sep 17 00:00:00 2001
From: a dinosaur <dino@a-dinosaur.com>
Date: Sat, 7 Sep 2024 13:50:40 +1000
Subject: [PATCH] ravine gaming

---
 .../Generator/StandardWorldGenerator.swift    | 45 +++++++++++++------
 1 file changed, 31 insertions(+), 14 deletions(-)

diff --git a/Sources/Voxelotl/Generator/StandardWorldGenerator.swift b/Sources/Voxelotl/Generator/StandardWorldGenerator.swift
index b9d72f4..9702cef 100644
--- a/Sources/Voxelotl/Generator/StandardWorldGenerator.swift
+++ b/Sources/Voxelotl/Generator/StandardWorldGenerator.swift
@@ -1,35 +1,52 @@
 struct StandardWorldGenerator: WorldGenerator {
   private var heightNoise: LayeredNoiseAlt<SimplexNoise<Float>>!
   private var terrainNoise: LayeredNoise<ImprovedPerlin<Float>>!
+  private var ravineNoise: LayeredNoise<SimplexNoise<Float>>!
+  private var ravineMask: LayeredNoise<SimplexNoise<Float>>!
   private var colorNoise: LayeredNoiseAlt<SimplexNoise<Float>>!
 
   public mutating func reset(seed: UInt64) {
     var random = PCG32Random(seed: SplitMix64.createState(seed: seed))
 
-    self.heightNoise  = .init(random: &random, octaves: 200, frequency: 0.0002,    amplitude:  2.000)
-    self.terrainNoise = .init(random: &random, octaves:  10, frequency: 0.01,      amplitude:  0.437)
-    self.colorNoise   = .init(random: &random, octaves: 150, frequency: 0.0006667, amplitude: 17.000)
+    self.heightNoise  = .init(random: &random, octaves: 28, frequency: 0.0008,   amplitude: 1.4)
+    self.terrainNoise = .init(random: &random, octaves: 10, frequency: 0.01,     amplitude: 0.437)
+    self.ravineNoise  = .init(random: &random, octaves: 12, frequency: 0.01)
+    self.ravineMask   = .init(random: &random, octaves:  2, frequency: 0.00241,  amplitude: 2)
+    self.colorNoise   = .init(random: &random, octaves: 15, frequency: 0.006667, amplitude: 3)
   }
 
   public func makeChunk(id chunkID: SIMD3<Int>) -> Chunk {
+    let blockFunc = { (height: Float, position: SIMD3<Float>) -> BlockType in
+#if true
+      let value = height + self.terrainNoise.get(position * SIMD3(1, 2, 1))
+      if value >= 0 {
+        return .air
+      }
+#else
+      if height >= 0 {
+        return .air
+      }
+#endif
+#if true
+      // Carve out ravines
+      if self.ravineMask.get(position * SIMD3(1, 0.441, 1)) >= 0.8 &&
+        abs(self.ravineNoise.get(position * SIMD3(1, 0.6, 1))) <= 0.1 { return .air }
+#endif
+      return .solid(.init(
+        hue: Float(180 + self.colorNoise.get(position) * 180),
+        saturation: 0.47, value: 0.9).linear)
+    }
+
     let chunkOrigin = chunkID &<< Chunk.shift
     var chunk = Chunk(position: chunkOrigin)
     for z in 0..<Chunk.size {
       for x in 0..<Chunk.size {
-        let height = self.heightNoise.get(SIMD2<Float>(chunkOrigin.xz &+ SIMD2<Int>(x, z)))
+        let fpos2D = SIMD2<Float>(chunkOrigin.xz &+ SIMD2<Int>(x, z))
+        let height = self.heightNoise.get(fpos2D)
         for y in 0..<Chunk.size {
           let ipos = SIMD3(x, y, z)
           let fpos = SIMD3<Float>(chunkOrigin &+ ipos)
-          let height = fpos.y / 64.0 + height
-          let value = height + self.terrainNoise.get(fpos * SIMD3(1, 2, 1))
-          let block: BlockType = if value < 0 {
-            .solid(.init(
-              hue: Float(180 + self.colorNoise.get(fpos) * 180),
-              saturation: 0.47, value: 0.9).linear)
-          } else {
-            .air
-          }
-          chunk.setBlock(internal: ipos, type: block)
+          chunk.setBlock(internal: ipos, type: blockFunc(fpos.y / 64.0 + height, fpos))
         }
       }
     }