added h sponge

h_sponge/depends.txt

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+default
+fractal_helpers

h_sponge/init.lua

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+-- Import Helpers
+dofile(minetest.get_modpath("fractal_helpers").."/helpers.lua")
+
+-- Parameters
+local YWATER = -31000
+local fractal_iteration = 6 -- min value 0, max value 10
+local DEBUG = true
+local fractal_block = minetest.get_content_id("default:stone")
+
+-- Set mapgen parameters
+local fractal_size = math.pow(3, fractal_iteration)
+local fractal_origin = math.floor(0 - fractal_size / 2)
+minetest.set_mapgen_params({mgname = "singlenode", flags = "nolight", water_level = YWATER})
+
+if DEBUG then
+  print ("[h_sponge] origin: "..fractal_origin)
+  print ("[h_sponge] size: "..fractal_size)
+end
+
+-- Localise data buffer
+local dbuf = {}
+
+
+-- ####################################################### --
+-- H SPONGE FUNCTIONS
+
+-- Tests if a point is in the H Sponge
+function sponge_test(d, x, y, z)
+  local d3 = d / 3
+
+  -- test if coords are outside of the set
+  local xOut = (x >= d3) and (x < 2 * d3)
+  local yIn = (y >= d3) and (y < 2 * d3)
+  local zOut = (z >= d3) and (z < 2 * d3)
+
+  -- return false unless only one value is outside of the range
+  if (xOut and zOut) or ((xOut or zOut) and not yIn) then
+    return false
+  elseif d3 >= 3 then
+    return sponge_test(d3, x % d3, y % d3, z % d3)
+  else
+    return true
+  end
+end
+
+
+-- ####################################################### --
+-- Minetest hooks
+
+-- Chunk generation function
+minetest.register_on_generated(function(minp, maxp, seed)
+  local t0 = os.clock()
+
+  local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
+  local area = VoxelArea:new{MinEdge = emin, MaxEdge = emax}
+  local data = vm:get_data(dbuf)
+
+  if outside_region(fractal_origin, fractal_size, minp, maxp) then
+    debug_message(DEBUG, "[h_sponge] Skipping "..region_text(minp, maxp))
+  else
+    debug_message(DEBUG, "[h_sponge] Generating blocks in "..region_text(minp, maxp))
+    
+    -- Iterate over fixed region for the h sponge
+    local minv, maxv = get_fractal_region(minp, maxp, fractal_origin, fractal_size - 1)
+
+    for z = minv.z, maxv.z do
+      for y = minv.y, maxv.y do
+        local vi = area:index(minv.x, y, z)
+        for x = minv.x, maxv.x do
+          if sponge_test(fractal_size, x - fractal_origin, y - fractal_origin, z - fractal_origin) then
+            data[vi] = fractal_block
+          end
+          vi = vi + 1
+        end
+      end
+    end
+  end
+  
+  vm:set_data(data)
+  vm:calc_lighting(minp, maxp)
+  vm:write_to_map(data)
+
+  if DEBUG then
+    local chugent = math.ceil((os.clock() - t0) * 1000)
+    print ("[h_sponge] "..chugent.." ms")
+  end
+end)
+  
+-- Player spawn point
+minetest.register_on_newplayer(function(player)
+  local elevation = fractal_origin + fractal_size + 1
+  player:setpos({x=fractal_origin, y=elevation, z=fractal_origin})
+end)