Register_on_generated local variables

[Kenney]

Very strange, but I'm guessing it's related to the 'local' variables. The first part of the code works (dirt_grass), the second (rock) however does nothing. Anyone able to tell what I'm doing wrong?

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Code: Select all

minetest.register_on_generated(function(minp, maxp, seed)
   for z = minp.z, maxp.z, 1 do
   for x = minp.x, maxp.x, 1 do
   for y = minp.y, maxp.y, 1 do
      local p = {x = x, y = y, z = z}
      local ran = math.random(1, 3)
      
      if minetest.get_node(p).name == 'voxus:dirt_grass' then
         minetest.set_node(p, {name='voxus:dirt_grass'})
      end
      
      if minetest.get_node(p).name == 'voxus:rock' and ran == 1 then
         local p_above = p
         p_above.y = p.y + 1
         
         local p_below = p
         p_below.y = p.y - 1
      
         if minetest.get_node(p_below).name == 'air' then
            minetest.set_node(p_below, {name='voxus:trunk'})
         end
         
         if minetest.get_node(p_above).name == 'air' then
            minetest.set_node(p_above, {name='voxus:mushroom_tall'})
         end
      end
   end
   end
   end
end)


[Sokomine]

The first part of the code works (dirt_grass), the second (rock) however does nothing.

How can you tell that? You seem to place the same node that was there already? At least in the dirt_grass part.

Anyone able to tell what I'm doing wrong?

Are you aware of voxelmanip? It's a lot faster than repeated get/set_node calls. There are also diffrent methods for spawning tree-like things. They're called "decorations" in MT. Pretty useful for mapgens :-)

[Kenney]

Dirt_grass has an on_construct handler which actually replaces it with a random other block, on_construct doesn't seem to fire when the map is being generated so I hacked that code in there to get it working.

Not aware of voxelmanip or how it works, decorations also do not seem to work properly and don't allow stuff like placing mushrooms in dark places.

[Sokomine]

Dirt_grass has an on_construct handler which actually replaces it with a random other block, on_construct doesn't seem to fire when the map is being generated so I hacked that code in there to get it working.

Why not put one of the random blocks there directly?

Not aware of voxelmanip or how it works, decorations also do not seem to work properly and don't allow stuff like placing mushrooms in dark places.

You really ought to look that up. It'll help you a lot and speed your game up considerably. Especially voxelmanip may be helpful for you. It's way faster than set/get_node. It does operate on content_id rather than on nodenames, handles param2 diffrently and does not directly handle metadata at all, but - did I say that already? :-) It's fast. As far as mushrooms go, there's a mod somewhere that places them. But in general, you ought to take a look at the Ethereal subgame. That one uses decorations to create an intresting landscape.

[prestidigitator]

For one thing your positional logic probably isn't doing what you expect it to do. Positions are table objects, stored by reference not value. So you can't just assign one variable referring to a table to another to get an independent copy. This code:

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Code: Select all

local p_above = p
p_above.y = p.y + 1
         
local p_below = p
p_below.y = p.y - 1


Will result in three variables all referring to the same position, which will have the same coordinates as the original position (since you first added then subtracted the same value from y). To copy a position, you can do one of the following:

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Code: Select all

local p2 = vector.new(p1);
-- OR
local p2 = { x = p1.x, y = p1.y, z = p1.z };
-- OR
local p2 = vector.new(p1.x, p1.y, p1.z);  -- EDIT: Fixed typo.  Had "p2.y" for last argument.


The second and third options give you a convenient place to create a new vector with different coordinates, since you can add or subtract right in the constructor. With the first option, you'd first make the copy and then modify the coordinate (e.g. p2.y = p2.y + 1).

[paramat]

The lua voxel manipulator processes nodes in bulk instead of individual calls to the map per node. Using it my lua mapgens have gone from a minute per chunk to a second per chunk generation time. Used in 'on generated' it processes a mapchunk at a time by using the already-created 'mapgen object voxelmanip'. See my mods for examples of use. Also https://forum.minetest.net/viewtopic.php?f=18&t=6396

[Kenney]

Thanks guys, decided to switch over to voxelmanip which is really just as easy to handle (see code below).

One question though; how would I go about getting the amount of light at the current node? I want mushrooms to only spawn in dark areas.

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Code: Select all

minetest.register_on_generated(function(minp, maxp, seed)
   local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
   
   local a = VoxelArea:new{
      MinEdge={x=emin.x, y=emin.y, z=emin.z},
      MaxEdge={x=emax.x, y=emax.y, z=emax.z},
   }
   
   local data = vm:get_data()
   local sidelen = maxp.x - minp.x + 1
   
   for z = minp.z, maxp.z do
   for y = minp.y, maxp.y do
   for x = minp.x, maxp.x do
      local vi = a:index(x, y, z)
      local vi_above = a:index(x, y + 1, z)
      local vi_below = a:index(x, y - 1, z)
      
      local node_current = minetest.get_name_from_content_id(data[vi])
      local node_above   = minetest.get_name_from_content_id(data[vi_above])
      local node_below   = minetest.get_name_from_content_id(data[vi_below])
      
      -- Mushrooms
      if node_current == 'voxus:rock' and node_above == 'air' then
         data[vi_above] = minetest.get_content_id("voxus:mushroom_beige")
      end
   end
   end
   end
   
   vm:set_data(data)
   vm:write_to_map(data)
   
   vm:get_light_data()
end)


[paramat]

See lua-api.txt, you can 'get' a luavoxelmanip of param1 values, which are the light values, it works just the same as the vm of content ids, process it then write it.

[Kenney]

See lua-api.txt, you can 'get' a luavoxelmanip of param1 values, which are the light values, it works just the same as the vm of content ids, process it then write it.

Ah fantastic, that was easy :) Got everything working now, thanks for the help everyone!