commit 01e1fe531eb54cc863bdb689ca2cb8467cfa39da
Author: paramat <mat.gregory@virginmedia.com>
Date:   Fri Mar 16 23:40:57 2018 +0000

    First commit

diff --git a/depends.txt b/depends.txt
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--- /dev/null
+++ b/depends.txt
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+default
diff --git a/init.lua b/init.lua
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+++ b/init.lua
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+-- 3D noise parameters for terrain.
+
+local np_terrain = {
+	offset = 0,
+	scale = 1,
+	spread = {x = 384, y = 192, z = 384},
+	seed = 5900033,
+	octaves = 5,
+	persist = 0.63,
+	lacunarity = 2.0,
+	--flags = ""
+}
+
+
+-- Set singlenode mapgen and disable engine lighting calculation.
+
+minetest.set_mapgen_params({mgname = "singlenode", flags = "nolight"})
+
+
+-- Get the content IDs for the nodes we will use.
+
+local c_sandstone = minetest.get_content_id("default:sandstone")
+local c_water     = minetest.get_content_id("default:water_source")
+
+
+-- Initialize noise object to nil.
+
+local nobj_terrain = nil
+
+
+-- Localise noise buffer table outside the loop, to be re-used for all
+-- mapchunks, therefore minimising memory use.
+
+local nbuf_terrain = {}
+
+
+-- Localise data buffer table outside the loop, to be re-used for all
+-- mapchunks, therefore minimising memory use.
+
+local dbuf = {}
+
+
+-- On generated function
+
+-- 'minp' and 'maxp' are the minimum and maximum positions of the mapchunk that
+-- define the 3D volume.
+minetest.register_on_generated(function(minp, maxp, seed)
+	-- Start time of mapchunk generation.
+	local t0 = os.clock()
+	
+	-- Side length of mapchunk
+	local sidelen = maxp.x - minp.x + 1
+	-- Required dimensions of the 3D noise perlin map.
+	local pmdims3d = {x = sidelen, y = sidelen, z = sidelen}
+	-- Create the perlin map noise object once only, during the generation of
+	-- the first mapchunk when 'nobj_terrain' is 'nil'.
+	nobj_terrain = nobj_terrain or
+		minetest.get_perlin_map(np_terrain, pmdims3d)
+	-- Create a flat array of noise values from the perlin map, with the
+	-- minimum point being 'minp'.
+	local nvals_terrain = nobj_terrain:get3dMap_flat(minp, nbuf_terrain)
+
+	-- Load the voxelmanip with the result of engine mapgen. Since we used
+	-- 'singlenode' mapgen this will be a mapchunk of air nodes.
+	local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
+	-- 'area' is used later to get the voxelmanip indexes for positions.
+	local area = VoxelArea:new{MinEdge = emin, MaxEdge = emax}
+	-- Get the content ID data from the voxelmanip in the form of a flat array.
+	local data = vm:get_data(dbuf)
+
+	-- Noise index for the flat array of noise values.
+	local ni = 1
+
+	-- Process the content IDs in 'data'.
+	-- The most useful order is a ZYX loop because:
+	-- 1. This matches the order of the 3D noise flat array.
+	-- 2. This allows us to simply increment the voxelmanip index along x rows.
+	for z = minp.z, maxp.z do
+	for y = minp.y, maxp.y do
+		-- Voxelmanip index for the flat array of content IDs.
+		-- Initialise to first node in this x row.
+		local vi = area:index(minp.x, y, z)
+		for x = minp.x, maxp.x do
+			-- Consider a 'solidness' value for each node,
+			-- let's call it 'density', where
+			-- density = density noise + density gradient.
+			local density_noise = nvals_terrain[ni]
+			-- Density gradient is a value that is 0 at water level (y = 1)
+			-- and falls in value with increasing y. This is necessary to
+			-- create a 'world surface' with only solid nodes deep underground
+			-- and only air high above water level.
+			-- Here '128' determines the typical maximum height of the terrain.
+			local density_gradient = (1 - y) / 128
+			-- Place solid nodes when 'density' > 0.
+			if density_noise + density_gradient > 0 then
+				data[vi] = c_sandstone
+			-- Otherwise if at or below water level place water.
+			elseif y <= 1 then
+				data[vi] = c_water
+			end
+
+			-- Increment noise index.
+			ni = ni + 1
+			-- Increment voxelmanip index along x row.
+			-- The voxelmanip index increases by 1 when
+			-- moving by 1 node in the +x direction.
+			vi = vi + 1
+		end
+	end
+	end
+
+	-- After processing, write content ID data back to the voxelmanip.
+	vm:set_data(data)
+	-- Calculate lighting for what we have created.
+	vm:calc_lighting()
+	-- Write what we have created to the world.
+	vm:write_to_map(data)
+	-- Liquid nodes were placed so set them flowing.
+	vm:update_liquids()
+
+	-- Print generation time of this mapchunk.
+	local chugent = math.ceil((os.clock() - t0) * 1000)
+	print ("[lvm_example] Mapchunk generation time "..chugent.." ms")
+end)