Minetest-WorldEditAdditions/worldeditadditions/lib/erode/river.lua

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local wea = worldeditadditions
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local wea_c = worldeditadditions_core
--- Parses a comma-separated side numbers list out into a list of numbers.
-- @param list string The command separated list to parse.
-- @returns number[] A list of side numbers.
local function parse_sides_list(list)
list = list:gsub("%s", "") -- Spaces are not permitted
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return wea_c.table.unique(wea_c.table.map(
wea_c.split(list, ","),
function(value) return tonumber(value) end
))
end
function worldeditadditions.erode.river(heightmap_initial, heightmap, heightmap_size, region_height, params_custom)
local params = {
steps = 1, -- Number of rounds/passes of the algorithm to run
lower_sides = "4,3", -- Cells with this many adjacent horizontal neighbours that are lower than the current pixel will be removed
raise_sides = "4,3", -- Cells with this many adjacect horizontal neighbours that are higher than the current pixel will be filled in
doraise = true, -- Whether to do raise operations or not
dolower = true -- Whether to do lower operations or not
}
-- Apply the custom settings
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wea_c.table.apply(params_custom, params)
params.lower_sides = parse_sides_list(params.lower_sides)
params.raise_sides = parse_sides_list(params.raise_sides)
local timings = {}
local filled = 0
local removed = 0
for i=1,params.steps do
-- print("[DEBUG:river] step ", i)
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-- wea_c.format.array_2d(heightmap, heightmap_size.x)
local time_start = wea_c.get_ms_time()
-- Store up changes to make and make them at the end of the step
-- This is important, because decisions
local fill = { } -- Indexes to add 1 to
local remove = { } -- Indexes to take 1 away from
for z = heightmap_size.z - 1, 0, -1 do
for x = heightmap_size.x - 1, 0, -1 do
local hi = z*heightmap_size.x + x
local thisheight = heightmap[hi]
-- print("[DEBUG:river] z", z, "x", x, "thisheight", thisheight)
local height_up = heightmap[hi]
local height_down = heightmap[hi]
local height_left = heightmap[hi]
local height_right = heightmap[hi]
if x > 0 then height_left = heightmap[z*heightmap_size.x + x-1] end
if x < heightmap_size.x - 1 then height_right = heightmap[z*heightmap_size.x + x+1] end
if z > 0 then height_up = heightmap[(z-1)*heightmap_size.x + x] end
if z < heightmap_size.z - 1 then height_down = heightmap[(z+1)*heightmap_size.x + x] end
-- Whether this pixel is on the edge
local isedge = x <= 0
or z <= 0
or x >= heightmap_size.x - 1
or z >= heightmap_size.z - 1
local sides_higher = 0 -- Number of sides higher than this pixel
local sides_lower = 0 -- Number of sides lower than this pixel
if not isedge then
if height_down > thisheight then sides_higher = sides_higher + 1 end
if height_up > thisheight then sides_higher = sides_higher + 1 end
if height_left > thisheight then sides_higher = sides_higher + 1 end
if height_right > thisheight then sides_higher = sides_higher + 1 end
if height_down < thisheight then sides_lower = sides_lower + 1 end
if height_up < thisheight then sides_lower = sides_lower + 1 end
if height_left < thisheight then sides_lower = sides_lower + 1 end
if height_right < thisheight then sides_lower = sides_lower + 1 end
end
-- Perform an action, but only if we're not on the edge
-- This is important, as we can't accurately tell how many
-- adjacent neighbours a pixel on the edge has.
local action = "none"
if not isedge then
if sides_higher > sides_lower then
for _,sidecount in ipairs(params.raise_sides) do
if sidecount == sides_higher then
action = "fill"
break
end
end
else
for _i,sidecount in ipairs(params.lower_sides) do
if sidecount == sides_lower then
action = "remove"
break
end
end
end
end
if action == "fill" and params.doraise then
table.insert(fill, hi)
filled = filled + 1
elseif action == "remove" and params.dolower then
table.insert(remove, hi)
removed = removed + 1
end
-- print("[DEBUG:river] sides_higher", sides_higher, "sides_lower", sides_lower, "action", action)
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-- wea_c.format.array_2d(heightmap, heightmap_size.x)
end
end
for _i,hi in ipairs(fill) do
heightmap[hi] = heightmap[hi] + 1
end
for _i,hi in ipairs(remove) do
heightmap[hi] = heightmap[hi] - 1
end
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table.insert(timings, wea_c.get_ms_time() - time_start)
end
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return true, params.steps.." steps made, raising "..filled.." and lowering "..removed.." columns in "..wea_c.format.human_time(wea_c.sum(timings)).." (~"..wea_c.format.human_time(wea_c.average(timings)).." per step)"
end