initial draft / PoC

.github/workflows/luacheck.yml

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+name: luacheck
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: apt
+      run: sudo apt-get install -y luarocks
+    - name: luacheck install
+      run: luarocks install --local luacheck
+    - name: luacheck run
+      run: $HOME/.luarocks/bin/luacheck ./

.luacheckrc

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+
+globals = {
+	"build_mirror",
+}
+
+read_globals = {
+	-- Stdlib
+	string = {fields = {"split"}},
+	table = {fields = {"copy", "getn"}},
+
+	-- Minetest
+	"minetest",
+	"vector", "ItemStack",
+	"dump",
+
+	-- Deps
+	"default"
+}

chatcommands.lua

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+
+
+--[[
+/mirror y
+/mirror x
+/mirror z
+/mirror set
+/mirror off
+--]]
+
+minetest.register_chatcommand("mirror", {
+  params = "[set|x|y|z|off]",
+  description = "",
+  func = function(name, param)
+    local player = minetest.get_player_by_name(name)
+    if not player then
+      return false, "Player not online!"
+    end
+
+    if param == "off" then
+      build_mirror.x[name] = nil
+      build_mirror.y[name] = nil
+      build_mirror.z[name] = nil
+      build_mirror.update_hud(player)
+      return true, "Mirror disabled"
+
+    -- TODO: set by punching a node
+    elseif param == "set" then
+      local ppos = player:get_pos()
+      build_mirror.pos[name] = vector.round(ppos)
+      build_mirror.update_hud(player)
+      return true, "Set mirror-position to " .. minetest.pos_to_string(build_mirror.pos[name])
+
+    elseif param == "x" then
+      build_mirror.x[name] = not build_mirror.x[name]
+      build_mirror.update_hud(player)
+      if build_mirror.x[name] then
+        return true, "X-Axis mirror: enabled"
+      else
+        return true, "X-Axis mirror: disabled"
+      end
+
+    elseif param == "y" then
+      build_mirror.y[name] = not build_mirror.y[name]
+      build_mirror.update_hud(player)
+      if build_mirror.y[name] then
+        return true, "Y-Axis mirror: enabled"
+      else
+        return true, "Y-Axis mirror: disabled"
+      end
+
+    elseif param == "z" then
+      build_mirror.z[name] = not build_mirror.z[name]
+      build_mirror.update_hud(player)
+      if build_mirror.z[name] then
+        return true, "Z-Axis mirror: enabled"
+      else
+        return true, "Z-Axis mirror: disabled"
+      end
+    end
+
+    return false, "Invalid command!"
+  end
+})

cleanup.lua

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+minetest.register_on_leaveplayer(function(player)
+  local playername = player:get_player_name()
+  build_mirror.x[playername] = nil
+  build_mirror.y[playername] = nil
+  build_mirror.z[playername] = nil
+  build_mirror.pos[playername] = nil
+end)

dev/minetest.conf

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+default_privs = interact, shout, zoom, fly, privs

dev/start.sh

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+#!/bin/sh
+
+docker run --rm -it \
+	-u root:root \
+	-v $(pwd)/minetest.conf:/etc/minetest/minetest.conf \
+	-v $(pwd)/../:/root/.minetest/worlds/world/worldmods/build_mirror \
+	-v build_mirror_world:/root/.minetest/worlds/world/ \
+	--network host \
+	registry.gitlab.com/minetest/minetest/server:5.2.0

dig.lua

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+
+
+local function dig_mirrored(pos, mirror_pos, mirrors)
+  local mirrored_pos = { x = pos.x, y = pos.y, z = pos.z }
+
+  if mirrors.x then
+    mirrored_pos.x = mirror_pos.x - (pos.x - mirror_pos.x)
+  end
+  if mirrors.y then
+    mirrored_pos.y = mirror_pos.y - (pos.y - mirror_pos.y)
+  end
+  if mirrors.z then
+    mirrored_pos.z = mirror_pos.z - (pos.z - mirror_pos.z)
+  end
+
+  minetest.log("action", "[mirror] digging at " .. minetest.pos_to_string(mirrored_pos))
+  minetest.set_node(mirrored_pos, { name = "air" })
+end
+
+minetest.register_on_dignode(function(pos, _, digger)
+  if not digger then
+    return
+  end
+
+  local playername = digger:get_player_name()
+  local mirror_pos = build_mirror.pos[playername]
+
+  if not mirror_pos then
+    return
+  end
+
+  local ppos = digger:get_pos()
+  if vector.distance(ppos, pos) > build_mirror.max_range then
+    minetest.chat_send_player(playername, "[Build mirror] out of range!")
+  end
+
+  if build_mirror.x[playername] then
+    dig_mirrored(pos, mirror_pos, { x=true })
+  end
+
+  if build_mirror.y[playername] then
+    dig_mirrored(pos, mirror_pos, { y=true })
+  end
+
+  if build_mirror.z[playername] then
+    dig_mirrored(pos, mirror_pos, { z=true })
+  end
+
+  if build_mirror.x[playername] and build_mirror.z[playername] then
+    dig_mirrored(pos, mirror_pos, { x=true, z=true })
+  end
+
+  if build_mirror.y[playername] and build_mirror.x[playername] then
+    dig_mirrored(pos, mirror_pos, { y=true, x=true })
+  end
+
+  if build_mirror.y[playername] and build_mirror.z[playername] then
+    dig_mirrored(pos, mirror_pos, { y=true, z=true })
+  end
+
+  if build_mirror.x[playername] and build_mirror.y[playername] and build_mirror.z[playername] then
+    dig_mirrored(pos, mirror_pos, { x=true, y=true, z=true })
+  end
+end)

hud.lua

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+
+-- playername => id
+local waypoint = {}
+
+function build_mirror.update_hud(player)
+  local playername = player:get_player_name()
+  local mirror_enabled = build_mirror.x[playername] or
+    build_mirror.y[playername] or
+    build_mirror.z[playername]
+
+  if waypoint[playername] then
+    -- update
+    if mirror_enabled then
+      -- update position
+      player:hud_change(waypoint[playername], "world_pos", build_mirror.pos[playername])
+    else
+      -- remove hud element
+      player:hud_remove(waypoint[playername])
+      waypoint[playername] = nil
+    end
+  else
+    if build_mirror.pos[playername] then
+      -- create new id
+      local id = player:hud_add({
+        hud_elem_type = "waypoint",
+        name = "Build mirror",
+        text = "m",
+        number = 0xFF0000,
+        world_pos = build_mirror.pos[playername]
+      })
+      waypoint[playername] = id
+    end
+  end
+end

init.lua

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+
+build_mirror = {
+
+  -- max radius around mirror
+  max_range = 100,
+
+  -- playername => pos
+  pos = {},
+
+  -- playername => true
+  x = {},
+  y = {},
+  z = {}
+}
+
+
+local MP = minetest.get_modpath(minetest.get_current_modname())
+dofile(MP .. "/common.lua")
+dofile(MP .. "/chatcommands.lua")
+dofile(MP .. "/hud.lua")
+dofile(MP .. "/place.lua")
+dofile(MP .. "/dig.lua")
+dofile(MP .. "/cleanup.lua")

mod.conf

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+name = build_mirror
+optional_depends = screwdriver

place.lua

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+
+local function place_mirrored(pos, node, mirror_pos, mirrors)
+  local mirrored_pos = { x = pos.x, y = pos.y, z = pos.z }
+
+  if mirrors.x then
+    mirrored_pos.x = mirror_pos.x - (pos.x - mirror_pos.x)
+  end
+  if mirrors.y then
+    mirrored_pos.y = mirror_pos.y - (pos.y - mirror_pos.y)
+  end
+  if mirrors.z then
+    mirrored_pos.z = mirror_pos.z - (pos.z - mirror_pos.z)
+  end
+
+  minetest.log("action",
+    "[mirror] placing " .. node.name ..
+    " with param2 " .. node.param2 ..
+    " at " .. minetest.pos_to_string(mirrored_pos)
+  )
+  minetest.set_node(mirrored_pos, node)
+end
+
+minetest.register_on_placenode(function(pos, newnode, placer)
+  if not placer then
+    return
+  end
+
+  local playername = placer:get_player_name()
+  local mirror_pos = build_mirror.pos[playername]
+
+  if not mirror_pos then
+    return
+  end
+
+  local ppos = placer:get_pos()
+  if vector.distance(ppos, pos) > build_mirror.max_range then
+    minetest.chat_send_player(playername, "[Build mirror] out of range!")
+  end
+
+  if build_mirror.x[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { x=true })
+  end
+
+  if build_mirror.y[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { y=true })
+  end
+
+  if build_mirror.z[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { z=true })
+  end
+
+  if build_mirror.x[playername] and build_mirror.z[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { x=true, z=true })
+  end
+
+  if build_mirror.y[playername] and build_mirror.x[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { y=true, x=true })
+  end
+
+  if build_mirror.y[playername] and build_mirror.z[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { y=true, z=true })
+  end
+
+  if build_mirror.x[playername] and build_mirror.y[playername] and build_mirror.z[playername] then
+    place_mirrored(pos, newnode, mirror_pos, { x=true, y=true, z=true })
+  end
+end)