Dialogues: Added function to select random dialogues for NPCs from random data.

Modified NPCs so random dialogues are chosen on initialization.
Added function to start a dialogue, choosing randomly NPCs dialogues.
Changed NPC code to use new dialogue code

dialogue.lua

@@ -0,0 +1,189 @@
+-- NPC dialogue code by Zorman2000
+
+npc.dialogue = {}
+
+npc.dialogue.POSITIVE_GIFT_ANSWER_PREFIX = "Yes, give "
+npc.dialogue.NEGATIVE_ANSWER_LABEL = "Nevermind"
+
+npc.dialogue.MIN_DIALOGUES = 2
+npc.dialogue.MAX_DIALOGUES = 4
+
+-- This table contains the answers of dialogue boxes
+npc.dialogue.dialogue_results = {
+	yes_no_dialogue = {}
+}
+
+-- Dialogue box definitions
+-- The dialogue boxes are used for the player to interact with the
+-- NPC in dialogues.
+--------------------------------------------------------------------
+-- Multi-option dialogue
+local function create_formspec(options, close_option) 
+	local options_length = table.getn(options) + 1	
+	local formspec_height = (options_length * 0.7) + 1
+	local formspec = "size[7,"..tostring(formspec_height).."]"
+	for i, opt in ipairs(options) do
+		local y = 0.7;
+		if i > 1 then
+			y = (y * i)
+		end
+		formspec = formspec.."button[0.5,"..y..";6,0.5;opt"..tostring(i)..";"..options[i].opt.."]"
+	end
+	formspec = formspec.."button_exit[0.5,"..(formspec_height - 1)..";6,0.5;exit;"..close_option.."]"
+	return formspec
+end
+
+-- This function is used for showing a yes/no dialogue formspec
+function npc.dialogue.show_yes_no_dialogue(prompt, 
+										   positive_answer_label,
+										   positive_callback,
+										   negative_answer_label,
+										   negative_callback,
+										   player_name)
+
+	local formspec = "size[7,3]"..
+					 "label[0.5,0.1;"..prompt.."]"..
+						"button_exit[0.5,1.15;6,0.5;yes_option;"..positive_answer_label.."]"..
+						"button_exit[0.5,1.95;6,0.5;no_option;"..negative_answer_label.."]"	
+
+	-- Create entry into responses table
+	npc.dialogue.dialogue_results.yes_no_dialogue[1] = {
+		name = player_name, 
+		response = "",
+		yes_callback = positive_callback,
+		no_callback = negative_callback
+	}
+
+	minetest.show_formspec(player_name, "advanced_npc:yes_no", formspec)
+end
+
+-- Dialogue methods
+-- Select random dialogue objects for an NPC based on sex
+-- and the relationship phase with player
+function npc.dialogue.select_random_dialogues_for_npc(sex, phase)
+	local result = {}
+	local dialogues = npc.data.DIALOGUES.female
+	if sex == npc.MALE then
+		dialogues = npc.data.DIALOGUES.male
+	end
+	dialogues = dialogues[phase]
+
+	-- Determine how many dialogue lines the NPC will have
+	local number_of_dialogues = math.random(npc.dialogue.MIN_DIALOGUES, npc.dialogue.MAX_DIALOGUES)
+
+	for i = 1,number_of_dialogues do
+		result[i] = dialogues[math.random(1, #dialogues)]
+	end
+
+	return result
+end
+
+-- This function will choose randomly a dialogue from the NPC data
+-- and process it. 
+function npc.dialogue.start_dialogue(self, player)
+	-- Choose a dialogue randomly
+	local dialogue = self.dialogues[math.random(1, #self.dialogues)]
+	npc.dialogue.process_dialogue(dialogue, player:get_player_name())
+end
+
+-- This function processes a dialogue object and performs
+-- actions depending on what is defined in the object 
+function npc.dialogue.process_dialogue(dialogue, player_name)
+	-- Send dialogue line
+	if dialogue.text then
+		minetest.chat_send_player(player_name, dialogue.text)
+	end
+	-- TODO: Add support for flag, multi-option dialogue
+	-- and their actions
+end
+
+-----------------------------------------------------------------------------
+-- Functions for rotating NPC to look at player (taken from the API itself)
+-----------------------------------------------------------------------------
+local atan = function(x)
+	if x ~= x then
+		return 0
+	else
+		return math.atan(x)
+	end
+end
+
+
+local function rotate_npc_to_player(self)
+	local s = self.object:getpos()
+	local objs = minetest.get_objects_inside_radius(s, 4)
+	local lp = nil
+	local yaw = 0
+	
+	for n = 1, #objs do
+		if objs[n]:is_player() then
+			lp = objs[n]:getpos()
+			break
+		end
+	end
+	if lp then
+		local vec = {
+			x = lp.x - s.x,
+			y = lp.y - s.y,
+			z = lp.z - s.z
+		}
+
+		yaw = (atan(vec.z / vec.x) + math.pi / 2) - self.rotate
+
+		if lp.x > s.x then
+			yaw = yaw + math.pi
+		end
+	end
+	self.object:setyaw(yaw)
+end
+
+---------------------------------------------------------------------
+-- Drives conversation
+---------------------------------------------------------------------
+local function show_chat_option(npc_name, self, player_name, chat_options, close_option)
+	rotate_npc_to_player(self)
+	self.order = "stand"
+	
+	local chatline = get_random_chatline(chat_options)
+	minetest.chat_send_player(player_name, chatline.text)
+	if chatline.options ~= nil then
+		minetest.log("Current options: "..dump(chatline.options))
+		local formspec = create_formspec(chatline.options, close_option)
+		minetest.show_formspec(player_name, "rndform", formspec)
+	end
+	
+	self.order = "follow"
+end
+
+-- Function to get response by player name
+local function get_yes_no_dialogue_response_by_player_name(player_name)
+	for i = 1,#npc.dialogue.dialogue_results.yes_no_dialogue do
+		local current_result = npc.dialogue.dialogue_results.yes_no_dialogue[i]
+		if current_result.name == player_name then
+			return current_result
+		end
+	end
+	return nil
+end
+
+-- Handler for chat formspec
+minetest.register_on_player_receive_fields(function (player, formname, fields)
+	-- Additional checks for other forms should be handled here
+	if formname == "advanced_npc:yes_no" then
+		local player_name = player:get_player_name()
+
+		if fields then
+			local player_response = get_yes_no_dialogue_response_by_player_name(player_name)
+			if fields.yes_option then
+				player_response.response = true
+				player_response.yes_callback()
+			elseif fields.no_option then
+				player_response.response = false
+				player_response.no_callback()
+			end
+			minetest.log(player_name.." chose response: "
+				..dump(get_yes_no_dialogue_response_by_player_name(player_name).response))
+		end
+	end
+
+end)