working live preview

display.lua

@@ -1,4 +1,11 @@
 
+-- playername => minetest.pos_to_string(pos1) .. "/" .. minetest.pos_to_string(pos2)
+local active_entities = {}
+
+local function get_entity_key(pos1, pos2)
+	return minetest.pos_to_string(pos1) .. "/" .. minetest.pos_to_string(pos2)
+end
+
 minetest.register_entity("building_lib:display", {
 	initial_properties = {
 		physical = false,
@@ -8,19 +15,98 @@ minetest.register_entity("building_lib:display", {
 		visual_size = {x=10, y=10},
 		textures = {"building_lib_place.png"},
 		glow = 10
-	}
+	},
+	on_step = function(self)
+		local entry = active_entities[self.playername]
+		if not entry or entry ~= self.key then
+			-- not valid anymore
+			self.object:remove()
+		end
+	end
 })
 
 minetest.register_chatcommand("test", {
 	func = function(name)
 		local player = minetest.get_player_by_name(name)
 		local pos = player:get_pos()
-        local mapblock_center = mapblock_lib.get_mapblock_center(pos)
-
-        local ent = minetest.add_entity(mapblock_center, "building_lib:display")
-        ent:set_properties({
-            visual_size = {x=5, y=5},
-            nametag = "test"
-        })
+		local mapblock_pos = mapblock_lib.get_mapblock(pos)
+		building_lib.show_preview(name, mapblock_pos, vector.add(mapblock_pos, {x=1, y=1, z=0}))
 	end
 })
+
+local function add_preview_entity(playername, key, visual_size, pos, rotation)
+	local ent = minetest.add_entity(pos, "building_lib:display")
+	local luaent = ent:get_luaentity()
+	luaent.playername = playername
+	luaent.key = key
+	ent:set_properties({
+		visual_size = visual_size,
+	})
+	ent:set_rotation(rotation)
+end
+
+function building_lib.has_preview(playername)
+	return active_entities[playername]
+end
+
+function building_lib.show_preview(playername, mapblock_pos1, mapblock_pos2)
+	mapblock_pos2 = mapblock_pos2 or mapblock_pos1
+	local key = get_entity_key(mapblock_pos1, mapblock_pos2)
+	if active_entities[playername] == key then
+		-- already active on the same region
+		return
+	end
+	active_entities[playername] = key
+
+	local min, _ = mapblock_lib.get_mapblock_bounds_from_mapblock(mapblock_pos1)
+
+	local size_mapblocks = vector.subtract(vector.add(mapblock_pos2, 1), mapblock_pos1) -- 1 .. n
+	local size = vector.multiply(size_mapblocks, 16) -- 16 .. n
+	local half_size = vector.divide(size, 2) -- 8 .. n
+
+	-- z-
+	add_preview_entity(playername, key,
+		{x=size.x, y=size.y},
+		vector.add(min, {x=half_size.x-0.5, y=half_size.y-0.5, z=-0.5}),
+		{x=0, y=0, z=0}
+	)
+
+	-- z+
+	add_preview_entity(playername, key,
+		{x=size.x, y=size.y},
+		vector.add(min, {x=half_size.x-0.5, y=half_size.y-0.5, z=size.z-0.5}),
+		{x=0, y=0, z=0}
+	)
+
+	-- x-
+	add_preview_entity(playername, key,
+		{x=size.z, y=size.y},
+		vector.add(min, {x=-0.5, y=half_size.y-0.5, z=half_size.z-0.5}),
+		{x=0, y=math.pi/2, z=0}
+	)
+
+	-- x+
+	add_preview_entity(playername, key,
+		{x=size.z, y=size.y},
+		vector.add(min, {x=size.x-0.5, y=half_size.y-0.5, z=half_size.z-0.5}),
+		{x=0, y=math.pi/2, z=0}
+	)
+
+	-- y-
+	add_preview_entity(playername, key,
+		{x=size.x, y=size.z},
+		vector.add(min, {x=half_size.x-0.5, y=-0.5, z=half_size.z-0.5}),
+		{x=math.pi/2, y=0, z=0}
+	)
+
+	-- y+
+	add_preview_entity(playername, key,
+		{x=size.x, y=size.z},
+		vector.add(min, {x=half_size.x-0.5, y=size.y-0.5, z=half_size.z-0.5}),
+		{x=math.pi/2, y=0, z=0}
+	)
+end
+
+function building_lib.clear_preview(playername)
+	active_entities[playername] = nil
+end

tools.lua

@@ -101,3 +101,34 @@ minetest.register_tool("building_lib:remove", {
     on_use = function()
     end
 })
+
+-- check for tools
+local function pointed_check()
+    for _, player in ipairs(minetest.get_connected_players()) do
+        local itemstack = player:get_wielded_item()
+        local playername = player:get_player_name()
+        local name = itemstack and itemstack:get_name()
+        if name == "building_lib:place" then
+            local pointed_mapblock_pos = mapblock_lib.get_pointed_position(player, 2)
+            local meta = itemstack:get_meta()
+            local buildingname = meta:get_string("buildingname")
+            local building_def = building_lib.buildings[buildingname]
+            if not building_def then
+                building_lib.clear_preview(playername)
+                return
+            end
+            local size = building_lib.get_building_size(building_def)
+            local mapblock_pos2 = vector.add(pointed_mapblock_pos, vector.subtract(size, 1))
+            building_lib.show_preview(playername, pointed_mapblock_pos, mapblock_pos2)
+
+        elseif building_lib.has_preview(playername) then
+            building_lib.clear_preview(playername)
+        end
+    end
+    minetest.after(0, pointed_check)
+end
+
+minetest.after(0, pointed_check)
+minetest.register_on_leaveplayer(function(player)
+    building_lib.clear_preview(player:get_player_name())
+end)