modlib/minetest/liquid.lua

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-- Localize globals
local minetest, modlib, pairs = minetest, modlib, pairs
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-- Set environment
local _ENV = ...
setfenv(1, _ENV)
liquid_level_max = 8
--+ Calculates the corner levels of a flowingliquid node
--> 4 corner levels from -0.5 to 0.5 as list of `modlib.vector`
function get_liquid_corner_levels(pos)
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local node = minetest.get_node(pos)
local def = minetest.registered_nodes[node.name]
local source, flowing = def.liquid_alternative_source, node.name
local range = def.liquid_range or liquid_level_max
local neighbors = {}
for x = -1, 1 do
neighbors[x] = {}
for z = -1, 1 do
local neighbor_pos = {x = pos.x + x, y = pos.y, z = pos.z + z}
local neighbor_node = minetest.get_node(neighbor_pos)
local level
if neighbor_node.name == source then
level = 1
elseif neighbor_node.name == flowing then
local neighbor_level = neighbor_node.param2 % 8
level = (math.max(0, neighbor_level - liquid_level_max + range) + 0.5) / range
end
neighbor_pos.y = neighbor_pos.y + 1
local node_above = minetest.get_node(neighbor_pos)
neighbors[x][z] = {
air = neighbor_node.name == "air",
level = level,
above_is_same_liquid = node_above.name == flowing or node_above.name == source
}
end
end
local function get_corner_level(x, z)
local air_neighbor
local levels = 0
local neighbor_count = 0
for nx = x - 1, x do
for nz = z - 1, z do
local neighbor = neighbors[nx][nz]
if neighbor.above_is_same_liquid then
return 1
end
local level = neighbor.level
if level then
if level == 1 then
return 1
end
levels = levels + level
neighbor_count = neighbor_count + 1
elseif neighbor.air then
if air_neighbor then
return 0.02
end
air_neighbor = true
end
end
end
if neighbor_count == 0 then
return 0
end
return levels / neighbor_count
end
local corner_levels = {
{0, nil, 0},
{1, nil, 0},
{1, nil, 1},
{0, nil, 1}
}
for index, corner_level in pairs(corner_levels) do
corner_level[2] = get_corner_level(corner_level[1], corner_level[3])
corner_levels[index] = modlib.vector.subtract_scalar(modlib.vector.new(corner_level), 0.5)
end
return corner_levels
end
flowing_downwards = modlib.vector.new{0, -1, 0}
--+ Calculates the flow direction of a flowingliquid node
--> `modlib.minetest.flowing_downwards = modlib.vector.new{0, -1, 0}` if only flowing downwards
--> surface direction as `modlib.vector` else
function get_liquid_flow_direction(pos)
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local corner_levels = get_liquid_corner_levels(pos)
local max_level = corner_levels[1][2]
for index = 2, 4 do
local level = corner_levels[index][2]
if level > max_level then
max_level = level
end
end
local dir = modlib.vector.new{0, 0, 0}
local count = 0
for max_level_index, corner_level in pairs(corner_levels) do
if corner_level[2] == max_level then
for offset = 1, 3 do
local index = (max_level_index + offset - 1) % 4 + 1
local diff = corner_level - corner_levels[index]
if diff[2] ~= 0 then
diff[1] = diff[1] * diff[2]
diff[3] = diff[3] * diff[2]
if offset == 3 then
diff = modlib.vector.divide_scalar(diff, math.sqrt(2))
end
dir = dir + diff
count = count + 1
end
end
end
end
if count ~= 0 then
dir = modlib.vector.divide_scalar(dir, count)
end
if dir == modlib.vector.new{0, 0, 0} then
if minetest.get_node(pos).param2 % 32 > 7 then
return flowing_downwards
end
end
return dir
end