removal mode

init.lua

@@ -5,6 +5,7 @@ local MP = minetest.get_modpath("pick_and_place")
 dofile(MP .. "/common.lua")
 dofile(MP .. "/pointed.lua")
 dofile(MP .. "/configure.lua")
+dofile(MP .. "/remove.lua")
 dofile(MP .. "/serialize.lua")
 dofile(MP .. "/entity.lua")
 dofile(MP .. "/handle_node.lua")

place_tool.lua

@@ -7,19 +7,31 @@ minetest.register_tool("pick_and_place:place", {
         not_in_creative_inventory = 1
     },
     on_use = function(itemstack, player)
+        local playername = player:get_player_name()
+        local controls = player:get_player_control()
+
         local meta = itemstack:get_meta()
         local schematic = meta:get_string("schematic")
         local size = minetest.string_to_pos(meta:get_string("size"))
         local distance = vector.distance(vector.new(), size)
 
         local pos1 = pick_and_place.get_pointed_position(player, math.max(10, distance) + 5)
-        local success, msg = pick_and_place.deserialize(pos1, schematic)
-        if not success then
-            minetest.chat_send_player(player:get_player_name(), "Placement error: " .. msg)
+        local pos2 = vector.add(pos1, vector.subtract(size, 1))
+
+        if controls.aux1 then
+            -- removal
+            pick_and_place.remove_area(pos1, pos2)
+        else
+            -- placement
+            local success, msg = pick_and_place.deserialize(pos1, schematic)
+            if not success then
+                minetest.chat_send_player(playername, "Placement error: " .. msg)
+            end
         end
     end,
     on_step = function(itemstack, player)
         local playername = player:get_player_name()
+        local controls = player:get_player_control()
 
         local meta = itemstack:get_meta()
         local size = minetest.string_to_pos(meta:get_string("size"))
@@ -28,7 +40,13 @@ minetest.register_tool("pick_and_place:place", {
         local pos1 = pick_and_place.get_pointed_position(player, math.max(10, distance) + 5)
         local pos2 = vector.add(pos1, vector.subtract(size, 1))
 
-        pick_and_place.show_preview(playername, "pick_and_place_plus.png", "#0000ff", pos1, pos2)
+        if controls.aux1 then
+            -- removal preview
+            pick_and_place.show_preview(playername, "pick_and_place_minus.png", "#ff0000", pos1, pos2)
+        else
+            -- build preview
+            pick_and_place.show_preview(playername, "pick_and_place_plus.png", "#0000ff", pos1, pos2)
+        end
     end,
     on_deselect = function(_, player)
         local playername = player:get_player_name()

readme.md

@@ -22,6 +22,8 @@ Simple copy+paste operation
 * This will convert the pick-tool to a blue `pick_and_place:place` tool in your inventory
 * Use the place-tool to place your build anywhere in the world with the help of the preview-overlay
 
+**Pro-tip**: hold the `aux` key to switch to removal-mode
+
 ## Configure a template area
 
 Create a template for frequent reuse

remove.lua

@@ -0,0 +1,31 @@
+local air_cid = minetest.get_content_id("air")
+
+function pick_and_place.remove_area(pos1, pos2)
+    local manip = minetest.get_voxel_manip()
+	local e1, e2 = manip:read_from_map(pos1, pos2)
+	local area = VoxelArea:new({MinEdge=e1, MaxEdge=e2})
+
+    local node_data = manip:get_data()
+    local param2 = manip:get_param2_data()
+
+    for z=pos1.z,pos2.z do
+    for x=pos1.x,pos2.x do
+    for y=pos1.y,pos2.y do
+        local i = area:index(x,y,z)
+        node_data[i] = air_cid
+        param2[i] = 0
+    end
+    end
+    end
+
+    manip:set_data(node_data)
+    manip:set_param2_data(param2)
+    manip:write_to_map()
+
+    -- clear metadata
+    local nodes_with_meta = minetest.find_nodes_with_meta(pos1, pos2)
+    for _, pos in ipairs(nodes_with_meta) do
+        local meta = minetest.get_meta(pos)
+        meta:from_table({})
+    end
+end