From 0dee65ca1d90fe7469b1b38076d8f28f2834d51d Mon Sep 17 00:00:00 2001
From: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>
Date: Tue, 13 Jul 2021 00:15:23 +0100
Subject: [PATCH] //noise2d: add red noise

---
 Chat-Command-Reference.md                     |  2 +
 worldeditadditions/lib/noise/engines/init.lua |  5 ++-
 worldeditadditions/lib/noise/engines/red.lua  | 39 +++++++++++++++++++
 worldeditadditions/lib/noise/make_2d.lua      |  2 +
 4 files changed, 46 insertions(+), 2 deletions(-)
 create mode 100644 worldeditadditions/lib/noise/engines/red.lua

diff --git a/Chat-Command-Reference.md b/Chat-Command-Reference.md
index 33edc42..3693be5 100644
--- a/Chat-Command-Reference.md
+++ b/Chat-Command-Reference.md
@@ -518,6 +518,8 @@ Algorithm	| Description
 ------------|--------------------------
 `perlin`	| Perlin noise. Functional, but currently contains artefacts I'm having difficulty tracking down.
 `sin`		| A sine wave created with `math.sin()`.
+`white`		| Random white noise.
+`red`       | Red noise - has a lower frequency than white noise.
 
 When specifying algorithm names, the `algorithm` parameter name is optional. For example, the following are both equivalent:
 
diff --git a/worldeditadditions/lib/noise/engines/init.lua b/worldeditadditions/lib/noise/engines/init.lua
index 921117e..8918c8b 100644
--- a/worldeditadditions/lib/noise/engines/init.lua
+++ b/worldeditadditions/lib/noise/engines/init.lua
@@ -2,9 +2,10 @@ local wea = worldeditadditions
 
 
 return {
-	available = { "perlin", "sin", "white" },
+	available = { "perlin", "sin", "white", "red" },
 	Perlin = dofile(wea.modpath.."/lib/noise/engines/perlin.lua"),
 	Sin = dofile(wea.modpath.."/lib/noise/engines/sin.lua"),
-	White = dofile(wea.modpath.."/lib/noise/engines/white.lua")
+	White = dofile(wea.modpath.."/lib/noise/engines/white.lua"),
+	Red = dofile(wea.modpath.."/lib/noise/engines/red.lua")
 	-- TODO: Follow https://www.redblobgames.com/articles/noise/introduction.html and implement different colours of noise (*especially* red and pink noise)
 }
diff --git a/worldeditadditions/lib/noise/engines/red.lua b/worldeditadditions/lib/noise/engines/red.lua
new file mode 100644
index 0000000..3ff9e13
--- /dev/null
+++ b/worldeditadditions/lib/noise/engines/red.lua
@@ -0,0 +1,39 @@
+local wea = worldeditadditions
+
+local White = dofile(wea.modpath.."/lib/noise/engines/white.lua")
+
+local Red = {}
+Red.__index = Red
+
+
+function Red.new(seed)
+	local result = {
+		seed = seed or math.random(),
+		white = White.new(seed)
+	}
+	setmetatable(result, Red)
+	return result
+end
+
+function Red:noise( x, y, z )
+	local values = {
+		self.white:noise(x, y, z),
+		self.white:noise(x + 1, y, z),
+		self.white:noise(x, y + 1, z),
+		self.white:noise(x, y, z + 1),
+		self.white:noise(x - 1, y, z),
+		self.white:noise(x, y - 1, z),
+		self.white:noise(x, y, z - 1),
+		self.white:noise(x, y - 1, z - 1),
+		self.white:noise(x - 1, y, z - 1),
+		self.white:noise(x - 1, y - 1, z),
+		self.white:noise(x - 1, y - 1, z - 1),
+		self.white:noise(x, y + 1, z + 1),
+		self.white:noise(x + 1, y, z + 1),
+		self.white:noise(x + 1, y + 1, z),
+		self.white:noise(x + 1, y + 1, z + 1),
+	}
+	return wea.average(values)
+end
+
+return Red
diff --git a/worldeditadditions/lib/noise/make_2d.lua b/worldeditadditions/lib/noise/make_2d.lua
index 9eba7f4..06043e4 100644
--- a/worldeditadditions/lib/noise/make_2d.lua
+++ b/worldeditadditions/lib/noise/make_2d.lua
@@ -21,6 +21,8 @@ function worldeditadditions.noise.make_2d(size, start_pos, params)
 			generator = wea.noise.engines.Sin.new()
 		elseif layer.algorithm == "white" then
 			generator = wea.noise.engines.White.new()
+		elseif layer.algorithm == "red" then
+			generator = wea.noise.engines.Red.new()
 		else -- We don't have any other generators just yet
 			return false, "Error: Unknown noise algorithm '"..tostring(layer.algorithm).."' in layer "..layer_i.." of "..#params.." (available algorithms: "..table.concat(wea.noise.engines.available, ", ")..")."
 		end