init, changed a few things for GEIGERnet-Server, added sounds for receiving RDS message

receiver.lua

@@ -0,0 +1,86 @@
+minetest.register_tool("ham_radio:handheld_receiver", {
+  description = "Handheld Radio Receiver",
+  wield_image = "ham_radio_receiver_handheld.png",
+  inventory_image = "ham_radio_receiver_handheld.png",
+  groups = { disable_repair = 1 },
+  -- left click - change frequency
+  on_use = function(itemstack, user, pointed_thing)
+    local keys = user:get_player_control()
+    local meta = itemstack:get_meta()
+    if keys.sneak then
+      -- left click with shift - RDS on/off
+      local is_rds_disabled = meta:get_string("rds_disabled")
+      if is_rds_disabled == "" then
+        meta:set_string("rds_disabled", "true")
+      else
+        meta:set_string("rds_disabled", "")
+      end
+      return itemstack
+    end
+    local frequency = meta:get_string("frequency")
+    minetest.show_formspec(user:get_player_name(), "ham_radio:configure_handheld_receiver",
+      table.concat({
+        "size[3,4]",
+        "image[1,0;1,1;ham_radio_receiver_handheld.png]",
+        "field[0.25,2;3,1;frequency;Frequency;",tostring(frequency),"]",
+        "tooltip[frequency;Integer number ",
+          ham_radio.settings.frequency.min,"-",
+          ham_radio.settings.frequency.max, "]",
+        "button_exit[0,3.5;3,1;;Done]"
+      },'')
+    )
+    return itemstack
+  end
+})
+
+minetest.register_on_player_receive_fields(function(player, formname, fields)
+  if formname ~= "ham_radio:configure_handheld_receiver" or not minetest.is_player(player) then
+    return false
+  end
+  if fields.frequency == nil then
+    -- form is not sent
+    return
+  end
+  local is_frequency_valid = ham_radio.validate_frequency(fields.frequency, true)
+  if is_frequency_valid.result == false then
+    ham_radio.errormsg(player, is_frequency_valid.message)
+    return false
+  end
+  local item = player:get_wielded_item()
+  local meta = item:get_meta()
+  meta:set_string("frequency", fields.frequency)
+  -- play radio sound
+  ham_radio.play_tuning_sound(player)
+   -- replace wielded item with new metadata
+  player:set_wielded_item(item)
+   -- reset rds messages
+  ham_radio.player_rds[player:get_player_name()] = nil
+  return true
+end)
+
+
+function ham_radio:locate_transmitter(player, transmitter_pos)
+  local player_pos = player:get_pos()
+  local player_look_vector = player:get_look_dir()
+  local player_direction = vector.add(player_pos, player_look_vector)
+
+  local coeff = 0.9
+  local distance_to_target = 0
+
+  local distance = vector.distance(player_pos, transmitter_pos)
+  if distance < 3 then
+    distance_to_target = 100
+    coeff = 0.99
+  else
+    distance_to_target = -0.0000000001*math.pow(distance,3)+0.00000145*math.pow(distance,2)-0.03*distance+100
+    if distance_to_target < 3 then
+      distance_to_target = 3
+    end
+  end
+
+  local distance2 = vector.distance(player_direction, transmitter_pos)
+  local signal_power = distance - distance2;
+
+  -- 0-100
+  return distance_to_target * coeff + distance_to_target * (1 - coeff) * signal_power;
+end