122 lines
4.6 KiB
Lua
122 lines
4.6 KiB
Lua
local test_minetest_find_nodes_in_area_can_count = function(dtime)
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-- This function tests that minetest.find_nodes_in_area() can
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-- count nodes correctly. If it fails, the engine can not be
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-- trusted to actually count how many nodes of a given type
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-- are in a given volume. Yes, *it* is bad if that happens.
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--
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-- If you are looking at this function because it executes at
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-- startup and crashes the game, by far the most stupid thing
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-- you could do is disabling it. Only an absolute moron would
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-- disable tests that ensure basic functionality still works.
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--
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-- Experience has taught me that such warnings are mostly not
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-- taken seriously by both Minetest mod & core developers. As
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-- there are very few situations in which someone would read
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-- the code of the function without a crash, you are probably
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-- asking yourself how bad it can be. Surely you will want an
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-- example of what will break if this test breaks. The answer
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-- to this simple question is equally simple and consists of a
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-- heartfelt “What the fuck did you say, you stupid fuckwad?”.
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--
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-- Alrighty then, let's get it on …
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local pos = { x=30999, y=30999, z=30999 }
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-- You think there is nothing there? Well, here is the thing:
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-- With standard settings you can only see map until x=30927,
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-- although the renderer can actually render up to x=31007 if
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-- you configure it to. Any statements given by minetest core
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-- devs that contradict the above assertion are probably lies.
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--
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-- In any way, this area should be so far out that no one has
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-- built here … yet. Now that you know it is possible, I know
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-- you want to. How though? I suggest to figure the technique
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-- out yourself, then go on and build invisible lag machines.
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local radius = 3
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local minp = vector.subtract(pos, radius)
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local maxp = vector.add(pos, radius)
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local nodename = "air"
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local c_nodename = minetest.get_content_id(nodename)
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-- Why not use minetest.set_node() here? Well, some mods do
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-- trigger on every placement of a node in the entire map …
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-- and we do not want to crash those mods in this test case.
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-- (Voxelmanip does not trigger callbacks – so all is well.)
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--
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-- And now for a funny story: I initially copied the following
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-- code from the Minetest developer wiki. Can you spot a typo?
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-- <https://dev.minetest.net/index.php?title=minetest.get_content_id&action=edit>
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local vm = minetest.get_voxel_manip()
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local emin, emax = vm:read_from_map(
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minp,
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maxp
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)
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local area = VoxelArea:new({
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MinEdge=emin,
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MaxEdge=emax
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})
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local data = vm:get_data()
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for z = minp.z, maxp.z do
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for y = minp.y, maxp.y do
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local vi = area:index(minp.x, y, z)
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for x = minp.x, maxp.y do
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data[vi] = c_nodename
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vi = vi + 1
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end
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end
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end
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vm:set_data(data)
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vm:write_to_map()
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local npos, nnum = minetest.find_nodes_in_area(
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minp,
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maxp,
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{ nodename }
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)
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local nodes_expected = math.pow( 1 + (2 * radius), 3 )
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local nodes_counted = nnum[nodename]
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local nodes_difference = nodes_expected - nodes_counted
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-- Originally, there was an assertion here that made the game
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-- crash at startup if Minetest forgot how to count. This was
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-- originally intended to avoid buggy engine releases, but it
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-- mostly made people upset and hindered debugging. Also, the
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-- assertion contained no error message hinting at the reason
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-- for the crash, making it exceptionally user-unfriendly. It
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-- follows that a game or mod should only assert on behaviour
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-- of the Lua code, not the underlying implementation, unless
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-- engine bugs are bad enough to permanently corrupt a world.
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if ( 0 ~= nodes_difference ) then
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minetest.debug(
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"minetest.find_nodes_in_area() failed to find " ..
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nodes_difference .. " nodes that were placed. " ..
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"Downgrading to Minetest 5.4.1 might fix this."
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)
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end
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end
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minetest.after( 0, test_minetest_find_nodes_in_area_can_count )
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local test_minetest_find_nodes_in_area_crash = function(dtime)
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-- And now for our feature presentation, where we call the
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-- function “minetest.find_nodes_in_area()” with a position
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-- out of bounds! Will it crash? Who knows‽ If it does, the
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-- workaround is not working though, so it should be patched.
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local pos = { x=32767, y=32767, z=32767 }
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-- Note that not all out of bounds values actually crash the
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-- function minetest.find_nodes_in_area()“. In fact, the vast
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-- majority of out of bounds values do not crash the function.
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local radius = 3
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local minp = vector.subtract(pos, radius)
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local maxp = vector.add(pos, radius)
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local nodename = "air"
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local npos, nnum = minetest.find_nodes_in_area(
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minp,
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maxp,
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{ nodename }
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)
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-- That's all, folks!
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end
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minetest.after( 0, test_minetest_find_nodes_in_area_crash )
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