VOXELGENERATOR: added new lua example script for using noise

src/modules/voxelgenerator/CMakeLists.txt

@@ -5,6 +5,7 @@ set(LUA_SRCS
 	scripts/modules/volume.lua
 	scripts/cover.lua
 	scripts/delete-rgb.lua
+	scripts/erode.lua
 	scripts/grass.lua
 	scripts/grid.lua
 	scripts/noise.lua

src/modules/voxelgenerator/lua/scripts/erode.lua

@@ -0,0 +1,36 @@
+local vol = require "modules.volume"
+
+function arguments()
+	return {
+		{ name = 'emptycnt', desc = 'The amount of empty voxels surrounding the voxel to erode.', type = 'int', default = '12', min = '1', max = '25' },
+		{ name = 'octaves', type = 'int', default = '4', min = '1', max = '10' },
+		{ name = 'lacunarity', desc = 'Scales the frequency', type = 'float', default = '1.0', min = '-3', max = '3'  },
+		{ name = 'gain', desc = 'Scales the amplitude', type = 'float', default = '0.5', min = '-3', max = '3' },
+		{ name = 'threshold', desc = 'Noise threshold', type = 'float', default = '0.3', min = '-1', max = '1' }
+	}
+end
+
+function main(node, region, color, emptycnt, octaves, lacunarity, gain, threshold)
+	local volume = node:volume()
+
+	local visitor = function (volume, x, y, z)
+		local adjacent = vol.countEmptyAround(volume, x, y, z)
+		if (adjacent >= emptycnt) then
+			local size = region:size()
+			local p = vec3.new(x / size.x, y / size.y, z / size.z)
+			local r = noise.fBm3(p, octaves, lacunarity, gain)
+			if r >= threshold then
+				volume:setVoxel(x, y, z, -1)
+			end
+		end
+	end
+
+	local condition = function (volume, x, y, z)
+		local voxel = volume:voxel(x, y, z)
+		if voxel == color then
+			return true
+		end
+		return false
+	end
+	vol.conditionYXZ(volume, region, visitor, condition)
+end