FOSS gamedev and creative worlds

I am going to make a forcefield mod where undigable block (forcefield block) is placed around about 6 blocks from forcefield generator block when it has coal in it and takes a coal away every 10 times forcefield block is hit, every 10 seconds, or if any block is missing, and destroys all forcefield block when there is no more coal. I am stuck on part detecting if coal is in the forcefield generator and there will be way more help needed afterwards.

init.lua:

I think that has been made before, in the technic mod i think

I don't think there was any forcefield related mod.

EDIT: in minetest. there is one in minecraft.

place i need help on is



when I remove "if else" part it works. How can I fix it to detect if coal is in this node or not?

ch98 wrote:place i need help on is


when I remove "if else" part it works. How can I fix it to detect if coal is in this node or not?

I didn't try, but maybe you need a return before or after the print.

Topywo wrote:

ch98 wrote:place i need help on is


when I remove "if else" part it works. How can I fix it to detect if coal is in this node or not?

I didn't try, but maybe you need a return before or after the print.

ok, I will try that.

Edit: didn't work but thank you.

ch98 wrote:I don't think there was any forcefield related mod.

EDIT: in minetest. there is one in minecraft.

Theres one made by ShadowNinja:

https://github.com/RealBadAngel/technic/blob/master/technic/forcefield.lua

RealBadAngel wrote:

ch98 wrote:I don't think there was any forcefield related mod.

EDIT: in minetest. there is one in minecraft.

Theres one made by ShadowNinja:

https://github.com/RealBadAngel/technic/blob/master/technic/forcefield.lua

I didn't find anything in forum search and google search. Also, I want to make it coal driven without extra mods. Can you help me?

Is it legal to modify code from minetest default (furnace) for my mod?

ch98 wrote:Is it legal to modify code from minetest default (furnace) for my mod?

I do believe it was fair game for desert_uses
http://forum.minetest.net/viewtopic.php?id=3761

Perhaps there should be some sort of generic way of making stuff that burns stuff, rather than duplicating the furnace code from default?

hdastwb wrote:

ch98 wrote:Is it legal to modify code from minetest default (furnace) for my mod?

I do believe it was fair game for desert_uses
http://forum.minetest.net/viewtopic.php?id=3761

Perhaps there should be some sort of generic way of making stuff that burns stuff, rather than duplicating the furnace code from default?

I'm trying to but I can't get any good help so just in case I never get help.

All of the code in Minetest is under the Lesser GNU Public License v2.1 or later, while the textures are CC-By-SA 3.0. So yeah, it's legal to use the code/textures as long as you comply with those licenses.

InvRef:get_list(...) is, I believe, going to return you an array of ItemStacks. You probably want to either get a single item stack and test the type of item instead:



or ask the inventory whether there is any of a type of item in the whole list:



The inventory list being named "coal" is a little confusing in those examples. If you pretend instead that the inventory list were named "fuel", then they would look like:



Another possibility would be to use inventory callbacks (specifically allow_metadata_inventory_put and—if the node has multiple lists in its inventory—also allow_metadata_inventory_move) to ensure that ONLY coal can be stored in the inventory list. In that case you could be reasonably certain that if there is ANYTHING in the inventory list, then it must be coal:

prestidigitator wrote:InvRef:get_list(...) is, I believe, going to return you an array of ItemStacks. You probably want to either get a single item stack and test the type of item instead:

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Code: Select all

if inv:get_stack("coal", 1):get_name() == "coal" then ...


or ask the inventory whether there is any of a type of item in the whole list:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

if inv:contains_item("coal", ItemStack("coal")) then ...


The inventory list being named "coal" is a little confusing in those examples. If you pretend instead that the inventory list were named "fuel", then they would look like:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

if inv:get_stack("fuel", 1):get_name() == "coal" then ...

if inv:contains_item("fuel", ItemStack("coal")) then ...


Another possibility would be to use inventory callbacks (specifically allow_metadata_inventory_put and—if the node has multiple lists in its inventory—also allow_metadata_inventory_move) to ensure that ONLY coal can be stored in the inventory list. In that case you could be reasonably certain that if there is ANYTHING in the inventory list, then it must be coal:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

if not inv:is_empty("fuel") then ...


Thank you. That way worked great. (Unfortunately, I found similar code in instruction manual yesterday taking 3 hours but this works way better. Thank You.)
Do you know how to take a coal from any of the 18 boxes?

I also need to make it suck only coal and place item in big hollow cube with set diameter (hollow sphere is good too) without erasing solid objects.

ch98 wrote:Do you know how to take a coal from any of the 18 boxes?

If the boxes are all in one inventory list, you should be able to just do:



or, if you want to remove more than one all at once:



I'm not sure if that one will return a partial list if not all n items were available, if it will return nil/empty. You'll probably just have to try it.

ch98 wrote:I also need to make it suck only coal and place item in big hollow cube with set diameter (hollow sphere is good too) without erasing solid objects.

You'll need to think about how you really want to define "solid". If you mean nodes that a player couldn't normally walk through, you should be able to test the existing node's "walkable" flag. If you mean nodes you couldn't normally build over, you can test the node's "buildable_to" flag. If you really don't want to replace anything that might be interesting, you could do something very explicit like test for just "air", "default:water_source" and "default:water_flowing". In terms of the geometry, you could place a cubic or spherical shell using something like:



That's untested, but it should give you the idea. The placeNode(pos) function would be where you test each position to see if you should put a node there, and do so if the node matches your conception of "not solid". The one for the cubic shell could also be improved by removing redundancy, but this logic is probably a bit easier to understand and should be a good starting point.

prestidigitator wrote:

ch98 wrote:I also need to make it suck only coal and place item in big hollow cube with set diameter (hollow sphere is good too) without erasing solid objects.

You'll need to think about how you really want to define "solid". If you mean nodes that a player couldn't normally walk through, you should be able to test the existing node's "walkable" flag. If you mean nodes you couldn't normally build over, you can test the node's "buildable_to" flag. If you really don't want to replace anything that might be interesting, you could do something very explicit like test for just "air", "default:water_source" and "default:water_flowing". In terms of the geometry, you could place a cubic or spherical shell using something like:

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

local function placeNode(pos)
   ...
end

local function placeCubicShell(pos, sideLen)
   local s = math.floor(sideLen/2)
   for dx = -s, s do
      for dy = -s, s do
         placeNode({ x = pos.x + dx, y = pos.y + dy, z = pos.z - s })
         placeNode({ x = pos.x + dx, y = pos.y + dy, z = pos.z + s })
      end
   end
   for dy = -s, s do
      for dz = -s, s do
         placeNode({ x = pos.x - s, y = pos.y + dy, z = pos.z + dz })
         placeNode({ x = pos.x + s, y = pos.y + dy, z = pos.z + dz })
      end
   end
   for dz = -s, s do
      for dx = -s, s do
         placeNode({ x = pos.x + dx, y = pos.y - s, z = pos.z + dz })
         placeNode({ x = pos.x + dx, y = pos.y + s, z = pos.z + dz })
      end
   end
end

local function placeSphericalShell(pos, radius)
   local rSq = radius^2
   local rx = math.floor(radius)
   if rx > 0 then
      for dx = -rx, rx do
         local rz = math.floor(math.sqrt(rSq - dx^2))
         if rz > 0 then
            for dz = -rz, rz do
               local ry = math.floor(math.sqrt(rSq - dx^2 - dz^2))
               if ry > 0 then
                  placeNode({ x = pos.x + dx, y = pos.y - ry, z = pos.z + dz })
                  placeNode({ x = pos.x + dx, y = pos.y + ry, z = pos.z + dz })
               end
            end
         end
      end
   end
end


That's untested, but it should give you the idea. The placeNode(pos) function would be where you test each position to see if you should put a node there, and do so if the node matches your conception of "not solid". The one for the cubic shell could also be improved by removing redundancy, but this logic is probably a bit easier to understand and should be a good starting point.

Wow. exactly what I needed. (I also need a way to take coal from any of the 18 spaces to put coal)

All questions here are solved.
More help may be needed at http://forum.minetest.net/viewtopic.php?pid=85204#p85204