advtrains/textures/drwho_screwdriver.png

--atan2 counts angles clockwise, minetest does counterclockwise

minetest.register_privilege("train_place", {
	description = "Player can place trains on tracks not owned by player",
	give_to_singleplayer= false,
});
minetest.register_privilege("train_remove", {
	description = "Player can remove trains not owned by player",
	give_to_singleplayer= false,
});
minetest.register_privilege("train_operator", {
	description = "Player may operate trains and switch signals. Given by default. Revoke to prevent players from griefing automated subway systems.",
	give_to_singleplayer= true,
	default= true,
});

local wagon={
	collisionbox = {-0.5,-0.5,-0.5, 0.5,0.5,0.5},
	--physical = true,
	visual = "mesh",
	mesh = "wagon.b3d",
	visual_size = {x=3, y=3},
	textures = {"black.png"},
	is_wagon=true,
	wagon_span=1,--how many index units of space does this wagon consume
	has_inventory=false,
}


function wagon:train()
	return advtrains.trains[self.train_id]
end

--[[about 'initalized':
	when initialized is false, the entity hasn't got any data yet and should wait for these to be set before doing anything
	when loading an existing object (with staticdata), it will be set
	when instanciating a new object via add_entity, it is not set at the time on_activate is called.
	then, wagon:initialize() will be called
	
	wagon will save only uid in staticdata, no serialized table
]]
function wagon:on_activate(sd_uid, dtime_s)
	if sd_uid~="" then
		--destroy when loaded from static block.
		self.object:remove()
		return
	end
	self.object:set_armor_groups({immortal=1})
	self.entity_name=self.name
end

function wagon:get_staticdata()
	return advtrains.pcall(function()
		if not self:ensure_init() then return end
		atprint("[wagon "..((self.unique_id and self.unique_id~="" and self.unique_id) or "no-id").."]: saving to wagon_save")
		--serialize inventory, if it has one
		if self.has_inventory then
			local inv=minetest.get_inventory({type="detached", name="advtrains_wgn_"..self.unique_id})
			self.ser_inv=advtrains.serialize_inventory(inv)
		end
		--save to table before being unloaded
		advtrains.wagon_save[self.unique_id]=advtrains.merge_tables(self)
		advtrains.wagon_save[self.unique_id].entity_name=self.name
		advtrains.wagon_save[self.unique_id].name=nil
		advtrains.wagon_save[self.unique_id].object=nil
		return self.unique_id
	end)
end
--returns: uid of wagon
function wagon:init_new_instance(train_id, properties)
	self.unique_id=os.time()..os.clock()
	self.train_id=train_id
	for k,v in pairs(properties) do
		if k~="name" and k~="object" then
			self[k]=v
		end
	end
	self:init_shared()
	self.initialized=true
	atprint("init_new_instance "..self.unique_id.." ("..self.train_id..")")
	return self.unique_id
end
function wagon:init_from_wagon_save(uid)
	if not advtrains.wagon_save[uid] then
		self.object:remove()
		return
	end
	self.unique_id=uid
	for k,v in pairs(advtrains.wagon_save[uid]) do
		if k~="name" and k~="object" then
			self[k]=v
		end
	end
	if not self.train_id or not self:train() then
		self.object:remove()
		return
	end
	self:init_shared()
	self.initialized=true
	minetest.after(0.2, function() self:reattach_all() end)
	atprint("init_from_wagon_save "..self.unique_id.." ("..self.train_id..")")
end
function wagon:init_shared()
	if self.has_inventory then
		local uid_noptr=self.unique_id..""
		--to be used later
		local inv=minetest.create_detached_inventory("advtrains_wgn_"..self.unique_id, {
			allow_move = function(inv, from_list, from_index, to_list, to_index, count, player)
				return count
			end,
			allow_put = function(inv, listname, index, stack, player)
				return stack:get_count()
			end,
			allow_take = function(inv, listname, index, stack, player)
				return stack:get_count()
			end
		})
		if self.ser_inv then
			advtrains.deserialize_inventory(self.ser_inv, inv)
		end
		if self.inventory_list_sizes then
			for lst, siz in pairs(self.inventory_list_sizes) do
				inv:set_size(lst, siz)
			end
		end
	end
	if self.doors then
		self.door_anim_timer=0
		self.door_state=0
	end
	if self.custom_on_activate then
		self:custom_on_activate(dtime_s)
	end
end
function wagon:ensure_init()
	if self.initialized then
		if self.noninitticks then self.noninitticks=nil end
		return true
	end
	if not self.noninitticks then self.noninitticks=0 end
	self.noninitticks=self.noninitticks+1
	if self.noninitticks>20 then
		self.object:remove()
	else
		self.object:setvelocity({x=0,y=0,z=0})
	end
	return false
end

-- Remove the wagon
function wagon:on_punch(puncher, time_from_last_punch, tool_capabilities, direction)
	return advtrains.pcall(function()
		if not self:ensure_init() then return end
		if not puncher or not puncher:is_player() then
			return
		end
		if self.owner and puncher:get_player_name()~=self.owner and (not minetest.check_player_privs(puncher, {train_remove = true })) then
		   minetest.chat_send_player(puncher:get_player_name(), attrans("This wagon is owned by @1, you can't destroy it.", self.owner));
		   return
		end
		
		if minetest.settings:get_bool("creative_mode") then
			if not self:destroy() then return end
			
			local inv = puncher:get_inventory()
			if not inv:contains_item("main", self.name) then
				inv:add_item("main", self.name)
			end
		else
			local pc=puncher:get_player_control()
			if not pc.sneak then
				minetest.chat_send_player(puncher:get_player_name(), attrans("Warning: If you destroy this wagon, you only get some steel back! If you are sure, hold Sneak and left-click the wagon."))
				return
			end

			if not self:destroy() then return end

			local inv = puncher:get_inventory()
			for _,item in ipairs(self.drops or {self.name}) do
				inv:add_item("main", item)
			end
		end
	end)
end
function wagon:destroy()
	--some rules:
	-- you get only some items back
	-- single left-click shows warning
	-- shift leftclick destroys
	-- not when a driver is inside
	
	for _,_ in pairs(self.seatp) do
		return
	end
	
	if self.custom_may_destroy then
		if not self.custom_may_destroy(self, puncher, time_from_last_punch, tool_capabilities, direction) then
			return
		end
	end
	if self.custom_on_destroy then
		self.custom_on_destroy(self, puncher, time_from_last_punch, tool_capabilities, direction)
	end
	
	atprint("[wagon "..((self.unique_id and self.unique_id~="" and self.unique_id) or "no-id").."]: destroying")
	
	self.object:remove()

	table.remove(self:train().trainparts, self.pos_in_trainparts)
	advtrains.update_trainpart_properties(self.train_id)
	advtrains.wagon_save[self.unique_id]=nil
	if self.discouple then self.discouple.object:remove() end--will have no effect on unloaded objects
	return true
end


function wagon:on_step(dtime)
	return advtrains.pcall(function()
		if not self:ensure_init() then return end
		
		local t=os.clock()
		local pos = self.object:getpos()
		
		if not pos then
			atprint("["..self.unique_id.."][fatal] missing position (object:getpos() returned nil)")
			return
		end

		self.entity_name=self.name
		
		--is my train still here
		if not self.train_id or not self:train() then
			atprint("[wagon "..self.unique_id.."] missing train_id, destroying")
			self.object:remove()
			return
		end
		if not self.seatp then
			self.seatp={}
		end
		if not self.seatpc then
			self.seatpc={}
		end
		
		--Legacy: remove infotext since it does not work this way anyways
		self.infotext=nil

		--custom on_step function
		if self.custom_on_step then
			self:custom_on_step(self, dtime)
		end

		--driver control
		for seatno, seat in ipairs(self.seats) do
			local driver=self.seatp[seatno] and minetest.get_player_by_name(self.seatp[seatno])
			local has_driverstand=seat.driving_ctrl_access and self.seatp[seatno] and minetest.check_player_privs(self.seatp[seatno], {train_operator=true})
			if has_driverstand and driver then
				advtrains.update_driver_hud(driver:get_player_name(), self:train(), self.wagon_flipped)
			elseif driver then
				--only show the inside text
				local inside=self:train().text_inside or ""
				advtrains.set_trainhud(driver:get_player_name(), inside)
			end
			if driver and driver:get_player_control_bits()~=self.seatpc[seatno] then
				local pc=driver:get_player_control()
				self.seatpc[seatno]=driver:get_player_control_bits()
				
				if has_driverstand then
					--regular driver stand controls
					advtrains.on_control_change(pc, self:train(), self.wagon_flipped)
				else
					-- If on a passenger seat and doors are open, get off when W or D pressed.
					local pass = self.seatp[seatno] and minetest.get_player_by_name(self.seatp[seatno])
					if pass and self:train().door_open~=0 then
					local pc=pass:get_player_control()
						if pc.up or pc.down then
							self:get_off(seatno)
						end
					end		      
				end
				if pc.aux1 and pc.sneak then
					self:get_off(seatno)
				end
			end
		end
		
		--check infotext
		local outside=self:train().text_outside or ""
		if self.object:get_properties().infotext~=outside  then
			self.object:set_properties({infotext=outside})
		end
		
		local gp=self:train()
		local fct=self.wagon_flipped and -1 or 1
		--door animation
		if self.doors then
			if (self.door_anim_timer or 0)<=0 then
				local dstate = (gp.door_open or 0) * fct
				if dstate ~= self.door_state then
					local at
					--meaning of the train.door_open field:
					-- -1: left doors (rel. to train orientation)
					--  0: closed
					--  1: right doors
					--this code produces the following behavior:
					-- if changed from 0 to +-1, play open anim. if changed from +-1 to 0, play close.
					-- if changed from +-1 to -+1, first close and set 0, then it will detect state change again and run open.
					if self.door_state == 0 then
						at=self.doors.open[dstate]
						self.object:set_animation(at.frames, at.speed or 15, at.blend or 0, false)
						self.door_state = dstate
					else
						at=self.doors.close[self.door_state or 1]--in case it has not been set yet
						self.object:set_animation(at.frames, at.speed or 15, at.blend or 0, false)
						self.door_state = 0
					end
					self.door_anim_timer = at.time
				end
			else
				self.door_anim_timer = (self.door_anim_timer or 0) - dtime
			end
		end
		
		--DisCouple
		if self.pos_in_trainparts and self.pos_in_trainparts>1 then
			if gp.velocity==0 and not self.lock_couples then
				if not self.discouple or not self.discouple.object:getyaw() then
					local object=minetest.add_entity(pos, "advtrains:discouple")
					if object then
						local le=object:get_luaentity()
						le.wagon=self
						--box is hidden when attached, so unuseful.
						--object:set_attach(self.object, "", {x=0, y=0, z=self.wagon_span*10}, {x=0, y=0, z=0})
						self.discouple=le
					else
						atprint("Couldn't spawn DisCouple")
					end
				end
			else
				if self.discouple and self.discouple.object:getyaw() then
					self.discouple.object:remove()
				end
			end
		end
		--for path to be available. if not, skip step
		if not gp.path then
			self.object:setvelocity({x=0, y=0, z=0})
			return
		end
		if not self.pos_in_train then
			--why ever. but better continue next step...
			advtrains.update_trainpart_properties(self.train_id)
			return
		end
		
		local index=advtrains.get_real_path_index(self:train(), self.pos_in_train)
		--atprint("trainindex "..gp.index.." wagonindex "..index)
		
		--automatic get_on
		--needs to know index and path
		if self.door_entry and gp.door_open and gp.door_open~=0 and gp.velocity==0 then
			--using the mapping created by the trainlogic globalstep
			for i, ino in ipairs(self.door_entry) do
				--fct is the flipstate flag from door animation above
				local aci = index + ino*fct
				local ix1=gp.path[math.floor(aci)]
				local ix2=gp.path[math.floor(aci+1)]
				-- the two wanted positions are ix1 and ix2 + (2nd-1st rotated by 90deg)
				-- (x z) rotated by 90deg is (-z x)  (http://stackoverflow.com/a/4780141)
				local add = { x = (ix2.z-ix1.z)*gp.door_open, y = 0, z = (ix1.x-ix2.x)*gp.door_open }
				local pts1=vector.round(vector.add(ix1, add))
				local pts2=vector.round(vector.add(ix2, add))
				if minetest.get_item_group(minetest.get_node(pts1).name, "platform")>0 then
					local ckpts={
						pts1,
						pts2,
						vector.add(pts1, {x=0, y=1, z=0}),
						vector.add(pts2, {x=0, y=1, z=0}),
					}
					for _,ckpos in ipairs(ckpts) do
						local cpp=minetest.pos_to_string(ckpos)
						if advtrains.playersbypts[cpp] then
							self:on_rightclick(advtrains.playersbypts[cpp])
						end
					end
				end
			end
		end
		
		--position recalculation
		local first_pos=gp.path[math.floor(index)]
		local second_pos=gp.path[math.floor(index)+1]
		if not first_pos or not second_pos then
			--atprint(" object "..self.unique_id.." path end reached!")
			self.object:setvelocity({x=0,y=0,z=0})
			return
		end
		
		--checking for environment collisions(a 3x3 cube around the center)
		if not gp.recently_collided_with_env then
			local collides=false
			for x=-1,1 do
				for y=0,2 do
					for z=-1,1 do
						local node=minetest.get_node_or_nil(vector.add(first_pos, {x=x, y=y, z=z}))
						if (advtrains.train_collides(node)) then
							collides=true
						end
					end
				end
			end
			if collides then
				if self.collision_count and self.collision_count>10 then
					--enable collision mercy to get trains stuck in walls out of walls
					--actually do nothing except limiting the velocity to 1
					gp.velocity=math.min(gp.velocity, 1)
					gp.tarvelocity=math.min(gp.tarvelocity, 1)
				else
					gp.recently_collided_with_env=true
					gp.velocity=2*gp.velocity
					gp.movedir=-gp.movedir
					gp.tarvelocity=0
					self.collision_count=(self.collision_count or 0)+1
				end
			else
				self.collision_count=nil
			end
		end
		
		--FIX: use index of the wagon, not of the train.
		local velocity=(gp.velocity*gp.movedir)/(gp.path_dist[math.floor(index)] or 1)
		local acceleration=(gp.last_accel or 0)/(gp.path_dist[math.floor(index)] or 1)
		local factor=index-math.floor(index)
		local actual_pos={x=first_pos.x-(first_pos.x-second_pos.x)*factor, y=first_pos.y-(first_pos.y-second_pos.y)*factor, z=first_pos.z-(first_pos.z-second_pos.z)*factor,}
		local velocityvec={x=(first_pos.x-second_pos.x)*velocity*-1, z=(first_pos.z-second_pos.z)*velocity*-1, y=(first_pos.y-second_pos.y)*velocity*-1}
		local accelerationvec={x=(first_pos.x-second_pos.x)*acceleration*-1, z=(first_pos.z-second_pos.z)*acceleration*-1, y=(first_pos.y-second_pos.y)*acceleration*-1}
		
		--some additional positions to determine orientation
		local aposfwd=gp.path[math.floor(index+2)]
		local aposbwd=gp.path[math.floor(index-1)]
		
		local yaw
		if aposfwd and aposbwd then
			yaw=advtrains.get_wagon_yaw(aposfwd, second_pos, first_pos, aposbwd, factor)+math.pi--TODO remove when cleaning up
		else
			yaw=math.atan2((first_pos.x-second_pos.x), (second_pos.z-first_pos.z))
		end
		if self.wagon_flipped then
			yaw=yaw+math.pi
		end
		
		self.updatepct_timer=(self.updatepct_timer or 0)-dtime
		if not self.old_velocity_vector 
				or not vector.equals(velocityvec, self.old_velocity_vector)
				or not self.old_acceleration_vector 
				or not vector.equals(accelerationvec, self.old_acceleration_vector)
				or self.old_yaw~=yaw
				or self.updatepct_timer<=0 then--only send update packet if something changed
				self.object:setpos(actual_pos)
			self.object:setvelocity(velocityvec)
			self.object:setacceleration(accelerationvec)
			self.object:setyaw(yaw)
			self.updatepct_timer=2
			if self.update_animation then
				self:update_animation(gp.velocity)
			end
		end
		
		
		self.old_velocity_vector=velocityvec
		self.old_acceleration_vector=accelerationvec
		self.old_yaw=yaw
		atprintbm("wagon step", t)
	end)
end

function advtrains.get_real_path_index(train, pit)
	local pos_in_train_left=pit
	local index=train.index
	if pos_in_train_left>(index-math.floor(index))*(train.path_dist[math.floor(index)] or 1) then
		pos_in_train_left=pos_in_train_left - (index-math.floor(index))*(train.path_dist[math.floor(index)] or 1)
		index=math.floor(index)
		while pos_in_train_left>(train.path_dist[index-1] or 1) do
			pos_in_train_left=pos_in_train_left - (train.path_dist[index-1] or 1)
			index=index-1
		end
		index=index-(pos_in_train_left/(train.path_dist[index-1] or 1))
	else
		index=index-(pos_in_train_left/(train.path_dist[math.floor(index-1)] or 1))
	end
	return index
end

function wagon:on_rightclick(clicker)
	return advtrains.pcall(function()
		if not self:ensure_init() then return end
		if not clicker or not clicker:is_player() then
			return
		end
		if clicker:get_player_control().aux1 then
			--advtrains.dumppath(self:train().path)
			--minetest.chat_send_all("at index "..(self:train().index or "nil"))
			--advtrains.invert_train(self.train_id)
			atprint(dump(self))
			return
		end	
		local pname=clicker:get_player_name()
		local no=self:get_seatno(pname)
		if no then
			if self.seat_groups then
				local poss={}
				local sgr=self.seats[no].group
				for _,access in ipairs(self.seat_groups[sgr].access_to) do
					if self:check_seat_group_access(pname, access) then
						poss[#poss+1]={name=self.seat_groups[access].name, key="sgr_"..access}
					end
				end
				if self.has_inventory and self.get_inventory_formspec then
					poss[#poss+1]={name=attrans("Show Inventory"), key="inv"}
				end
				if self.owner==pname then
					poss[#poss+1]={name=attrans("Wagon properties"), key="prop"}
				end
				if not self.seat_groups[sgr].require_doors_open or self:train().door_open~=0 then
					poss[#poss+1]={name=attrans("Get off"), key="off"}
				else
					if clicker:get_player_control().sneak then
						poss[#poss+1]={name=attrans("Get off (forced)"), key="off"}
					else
						poss[#poss+1]={name=attrans("(Doors closed)"), key="dcwarn"}
					end
				end
				if #poss==0 then
					--can't do anything.
				elseif #poss==1 then
					self:seating_from_key_helper(pname, {[poss[1].key]=true}, no)
				else
					local form = "size[5,"..1+(#poss).."]"
					for pos,ent in ipairs(poss) do
						form = form .. "button_exit[0.5,"..(pos-0.5)..";4,1;"..ent.key..";"..ent.name.."]"
					end
					minetest.show_formspec(pname, "advtrains_seating_"..self.unique_id, form)
				end
			else
				self:get_off(no)
			end
		else
			--do not attach if already on a train
			if advtrains.player_to_train_mapping[pname] then return end
			if self.seat_groups then
				if #self.seats==0 then
					if self.has_inventory and self.get_inventory_formspec then
						minetest.show_formspec(pname, "advtrains_inv_"..self.unique_id, self:get_inventory_formspec(pname))
					end
					return
				end
				
				local doors_open = self:train().door_open~=0 or clicker:get_player_control().sneak
				for _,sgr in ipairs(self.assign_to_seat_group) do
					if self:check_seat_group_access(pname, sgr) then
						for seatid, seatdef in ipairs(self.seats) do
							if seatdef.group==sgr and not self.seatp[seatid] and (not self.seat_groups[sgr].require_doors_open or doors_open) then
								self:get_on(clicker, seatid)
								return
							end
						end
					end
				end
				minetest.chat_send_player(pname, attrans("Can't get on: wagon full or doors closed!"))
				minetest.chat_send_player(pname, attrans("Use Sneak+rightclick to bypass closed doors!"))
			else
				self:show_get_on_form(pname)
			end
		end
	end)
end

function wagon:get_on(clicker, seatno)
	if not self.seatp then self.seatp={}end
	if not self.seatpc then self.seatpc={}end--player controls in driver stands
	
	if not self.seats[seatno] then return end
	local oldno=self:get_seatno(clicker:get_player_name())
	if oldno then
		atprint("get_on: clearing oldno",seatno)
		advtrains.player_to_train_mapping[clicker:get_player_name()]=nil
		advtrains.clear_driver_hud(clicker:get_player_name())
		self.seatp[oldno]=nil
	end
	if self.seatp[seatno] and self.seatp[seatno]~=clicker:get_player_name() then
		atprint("get_on: throwing off",self.seatp[seatno],"from seat",seatno)
		self:get_off(seatno)
	end
	atprint("get_on: attaching",clicker:get_player_name())
	self.seatp[seatno] = clicker:get_player_name()
	self.seatpc[seatno] = clicker:get_player_control_bits()
	advtrains.player_to_train_mapping[clicker:get_player_name()]=self.train_id
	clicker:set_attach(self.object, "", self.seats[seatno].attach_offset, {x=0,y=0,z=0})
	clicker:set_eye_offset(self.seats[seatno].view_offset, self.seats[seatno].view_offset)
end
function wagon:get_off_plr(pname)
	local no=self:get_seatno(pname)
	if no then
		self:get_off(no)
	end
end
function wagon:get_seatno(pname)
	for no, cont in pairs(self.seatp) do
		if cont==pname then
			return no
		end
	end
	return nil
end
function wagon:get_off(seatno)
	if not self.seatp[seatno] then return end
	local pname = self.seatp[seatno]
	local clicker = minetest.get_player_by_name(pname)
	advtrains.player_to_train_mapping[pname]=nil
	advtrains.clear_driver_hud(pname)
	self.seatp[seatno]=nil
	self.seatpc[seatno]=nil
	if clicker then
		atprint("get_off: detaching",clicker:get_player_name())
		clicker:set_detach()
		clicker:set_eye_offset({x=0,y=0,z=0}, {x=0,y=0,z=0})
		local gp=self:train()
		--code as in step - automatic get on
		if self.door_entry and gp.door_open and gp.door_open~=0 and gp.velocity==0 and gp.index and gp.path then
			local index=advtrains.get_real_path_index(gp, self.pos_in_train)
			--using the mapping created by the trainlogic globalstep
			for i, ino in ipairs(self.door_entry) do
				local aci = index + ino*(self.wagon_flipped and -1 or 1)
				local ix1=gp.path[math.floor(aci)]
				local ix2=gp.path[math.floor(aci+1)]
				-- the two wanted positions are ix1 and ix2 + (2nd-1st rotated by 90deg)
				-- (x z) rotated by 90deg is (-z x)  (http://stackoverflow.com/a/4780141)
				-- multiplied by 2 here, to place off on platform, y of add is 1.
				local add = { x = (ix2.z-ix1.z)*gp.door_open, y = 0, z = (ix1.x-ix2.x)*gp.door_open}
				local oadd = { x = (ix2.z-ix1.z)*gp.door_open*2, y = 1, z = (ix1.x-ix2.x)*gp.door_open*2}
				local platpos=vector.round(vector.add(ix1, add))
				local offpos=vector.round(vector.add(ix1, oadd))
				atprint("platpos:", platpos, "offpos:", offpos)
				if minetest.get_item_group(minetest.get_node(platpos).name, "platform")>0 then
					minetest.after(0.2, function() clicker:setpos(offpos) end)
					return
				end
			end
		else--if not door_entry, or paths missing, fall back to old method
			local objpos=advtrains.round_vector_floor_y(self.object:getpos())
			local yaw=self.object:getyaw()
			local isx=(yaw < math.pi/4) or (yaw > 3*math.pi/4 and yaw < 5*math.pi/4) or (yaw > 7*math.pi/4)
			--abuse helper function
			for _,r in ipairs({-1, 1}) do
				local p=vector.add({x=isx and r or 0, y=0, z=not isx and r or 0}, objpos)
				local offp=vector.add({x=isx and r*2 or 0, y=1, z=not isx and r*2 or 0}, objpos)
				if minetest.get_item_group(minetest.get_node(p).name, "platform")>0 then
					minetest.after(0.2, function() clicker:setpos(offp) end)
					return
				end
			end
		end
	end
end
function wagon:show_get_on_form(pname)
	if not self.initialized then return end
	if #self.seats==0 then
		if self.has_inventory and self.get_inventory_formspec then
			minetest.show_formspec(pname, "advtrains_inv_"..self.unique_id, self:get_inventory_formspec(pname))
		end
		return
	end
	local form, comma="size[5,8]label[0.5,0.5;"..attrans("Select seat:").."]textlist[0.5,1;4,6;seat;", ""
	for seatno, seattbl in ipairs(self.seats) do
		local addtext, colorcode="", ""
		if self.seatp and self.seatp[seatno] then
			colorcode="#FF0000"
			addtext=" ("..self.seatp[seatno]..")"
		end
		form=form..comma..colorcode..seattbl.name..addtext
		comma=","
	end
	form=form..";0,false]"
	if self.has_inventory and self.get_inventory_formspec then
		form=form.."button_exit[1,7;3,1;inv;"..attrans("Show Inventory").."]"
	end
	minetest.show_formspec(pname, "advtrains_geton_"..self.unique_id, form)
end
function wagon:show_wagon_properties(pname)
	local numsgr=0
	if self.seat_groups then
		numsgr=#self.seat_groups
	end
	if not self.seat_access then
		self.seat_access={}
	end
	--[[
	fields: seat access: empty: everyone
	checkbox: lock couples
	button: save
	]]
	local form="size[5,"..(numsgr*1.5+7).."]"
	local at=0
	if self.seat_groups then
		for sgr,sgrdef in pairs(self.seat_groups) do
			local text = attrans("Access to @1",sgrdef.name)
			form=form.."field[0.5,"..(0.5+at*1.5)..";4,1;sgr_"..sgr..";"..text..";"..(self.seat_access[sgr] or "").."]"
			at=at+1
		end
	end
	form=form.."checkbox[0,"..(at*1.5)..";lock_couples;"..attrans("Lock couples")..";"..(self.lock_couples and "true" or "false").."]"
	if self:train() then --just in case
		form=form.."field[0.5,"..(1.5+at*1.5)..";4,1;text_outside;"..attrans("Text displayed outside on train")..";"..(self:train().text_outside or "").."]"
		form=form.."field[0.5,"..(2.5+at*1.5)..";4,1;text_inside;"..attrans("Text displayed inside train")..";"..(self:train().text_inside or "").."]"
	end
	form=form.."button_exit[0.5,"..(3+at*1.5)..";4,1;save;"..attrans("Save wagon properties").."]"
	minetest.show_formspec(pname, "advtrains_prop_"..self.unique_id, form)
end
minetest.register_on_player_receive_fields(function(player, formname, fields)
	return advtrains.pcall(function()
		local uid=string.match(formname, "^advtrains_geton_(.+)$")
		if uid then
			for _,wagon in pairs(minetest.luaentities) do
				if wagon.is_wagon and wagon.initialized and wagon.unique_id==uid then
					if fields.inv then
						if wagon.has_inventory and wagon.get_inventory_formspec then
							minetest.show_formspec(player:get_player_name(), "advtrains_inv_"..uid, wagon:get_inventory_formspec(player:get_player_name()))
						end
					elseif fields.seat then
						local val=minetest.explode_textlist_event(fields.seat)
						if val and val.type~="INV" and not wagon.seatp[player:get_player_name()] then
						--get on
							wagon:get_on(player, val.index)
							--will work with the new close_formspec functionality. close exactly this formspec.
							minetest.show_formspec(player:get_player_name(), formname, "")
						end
					end
				end
			end
		end
		uid=string.match(formname, "^advtrains_seating_(.+)$")
		if uid then
			for _,wagon in pairs(minetest.luaentities) do
				if wagon.is_wagon and wagon.initialized and wagon.unique_id==uid then
					local pname=player:get_player_name()
					local no=wagon:get_seatno(pname)
					if no then
						if wagon.seat_groups then
							wagon:seating_from_key_helper(pname, fields, no)
						end
					end
				end
			end
		end
		uid=string.match(formname, "^advtrains_prop_(.+)$")
		if uid then
			for _,wagon in pairs(minetest.luaentities) do
				if wagon.is_wagon and wagon.initialized and wagon.unique_id==uid then
					local pname=player:get_player_name()
					if pname~=wagon.owner then
						return true
					end
					if fields.save or not fields.quit then
						for sgr,sgrdef in pairs(wagon.seat_groups) do
							if fields["sgr_"..sgr] then
								local fcont = fields["sgr_"..sgr]
								wagon.seat_access[sgr] = fcont~="" and fcont or nil
							end
						end
						if fields.lock_couples then
							wagon.lock_couples = fields.lock_couples == "true"
						end
						if fields.text_outside then
							if fields.text_outside~="" then
								wagon:train().text_outside=fields.text_outside
							else
								wagon:train().text_outside=nil
							end
						end
						if fields.text_inside then
							if fields.text_inside~="" then
								wagon:train().text_inside=fields.text_inside
							else
								wagon:train().text_inside=nil
							end
						end
						
					end
				end
			end
		end
	end)
end)
function wagon:seating_from_key_helper(pname, fields, no)
	local sgr=self.seats[no].group
	for _,access in ipairs(self.seat_groups[sgr].access_to) do
		if fields["sgr_"..access] and self:check_seat_group_access(pname, access) then
			for seatid, seatdef in ipairs(self.seats) do
				if seatdef.group==access and not self.seatp[seatid] then
					self:get_on(minetest.get_player_by_name(pname), seatid)
					return
				end
			end
		end
	end
	if fields.inv and self.has_inventory and self.get_inventory_formspec then
		minetest.show_formspec(player:get_player_name(), "advtrains_inv_"..self.unique_id, wagon:get_inventory_formspec(player:get_player_name()))
	end
	if fields.prop and self.owner==pname then
		self:show_wagon_properties(pname)
	end
	if fields.dcwarn then
		minetest.chat_send_player(pname, attrans("Doors are closed! Use Sneak+rightclick to ignore the closed doors and get off!"))
	end
	if fields.off then
		self:get_off(no)
	end
end
function wagon:check_seat_group_access(pname, sgr)
	if not self.seat_access then
		return true
	end
	local sae=self.seat_access[sgr]
	if not sae or sae=="" then
		return true
	end
	for name in string.gmatch(sae, "%S+") do
		if name==pname then
			return true
		end
	end
	return false
end
function wagon:reattach_all()
	if not self.seatp then self.seatp={} end
	for seatno, pname in pairs(self.seatp) do
		local p=minetest.get_player_by_name(pname)
		if p then
			self:get_on(p ,seatno)
		end
	end
end

function advtrains.register_wagon(sysname, prototype, desc, inv_img)
	setmetatable(prototype, {__index=wagon})
	minetest.register_entity(":advtrains:"..sysname,prototype)
	
	minetest.register_craftitem(":advtrains:"..sysname, {
		description = desc,
		inventory_image = inv_img,
		wield_image = inv_img,
		stack_max = 1,
		
		on_place = function(itemstack, placer, pointed_thing)
			return advtrains.pcall(function()
				if not pointed_thing.type == "node" then
					return
				end
				

				local node=minetest.get_node_or_nil(pointed_thing.under)
				if not node then atprint("[advtrains]Ignore at placer position") return itemstack end
				local nodename=node.name
				if(not advtrains.is_track_and_drives_on(nodename, prototype.drives_on)) then
					atprint("no track here, not placing.")
					return itemstack
				end
				if not minetest.check_player_privs(placer, {train_place = true }) and minetest.is_protected(pointed_thing.under, placer:get_player_name()) then
					minetest.record_protection_violation(pointed_thing.under, placer:get_player_name())
					return
				end
				local conn1=advtrains.get_track_connections(node.name, node.param2)
				local id=advtrains.create_new_train_at(pointed_thing.under, advtrains.dirCoordSet(pointed_thing.under, conn1))
				
				local ob=minetest.add_entity(pointed_thing.under, "advtrains:"..sysname)
				if not ob then
					atprint("couldn't add_entity, aborting")
				end
				local le=ob:get_luaentity()
				
				le.owner=placer:get_player_name()
				
				local wagon_uid=le:init_new_instance(id, {})
				
				advtrains.add_wagon_to_train(le, id)
				if not minetest.settings:get_bool("creative_mode") then
					itemstack:take_item()
				end
				return itemstack
				
			end)
		end,
	})
end

--[[
	wagons can define update_animation(self, velocity) if they have a speed-dependent animation
	this function will be called when the velocity vector changes or every 2 seconds.
]]
ofs	hex dump	ascii
0000	89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 00 10 00 00 00 10 08 06 00 00 00 1f f3 ff	.PNG........IHDR................
0020	61 00 00 00 06 62 4b 47 44 00 ff 00 ff 00 ff a0 bd a7 93 00 00 00 09 70 48 59 73 00 00 0b 13 00	a....bKGD..............pHYs.....
0040	00 0b 13 01 00 9a 9c 18 00 00 00 07 74 49 4d 45 07 e0 03 05 10 1e 37 da 34 02 60 00 00 00 d5 49	............tIME......7.4.`....I
0060	44 41 54 38 cb cd 93 a1 6e c2 50 14 40 cf a3 cd 5e 4d 2b c8 0c 4d f5 3c 09 6a 09 41 81 c4 f4 0b	DAT8....n.P.@...^M+..M.<.j.A....
0080	ea ca 5f f0 03 fb 80 b9 fd 40 ed c4 24 92 54 23 27 b0 75 37 81 a4 a4 ed 9b 21 64 a2 8c 5b b7 63	.._......@..$.T#'.u7.....!d..[.c
00a0	df 3d 47 dc 9b 67 50 b2 dd ba 31 b0 04 56 40 0d 7c 02 3b 1f 3d f3 a6 e1 4d 84 18 70 51 c4 c2 f7	.=G..gP...1..V@.\|.;.=...M..pQ...
00c0	d9 8c 06 04 5e 45 98 94 25 a6 2c 19 89 f0 02 cc 86 04 8e 5d 57 ff 9e 6f 81 b3 a7 b5 a7 53 d9 db	....^E..%.,........]W..o.....S..
00e0	4b cd f3 24 21 49 ec 29 0c f9 f2 3c 3e 8c 46 ce b2 cc 05 41 40 db b6 c4 f1 fb 1a 78 02 0e c0 b7	K..$!I.)...<>.F....A@......x....
0100	4a 76 e0 d2 34 75 7d ef e6 91 6c ad a5 aa 2a 8a a2 30 83 02 1a f9 6e 40 2b f7 06 86 c8 7d 38 fe	Jv..4u}...l...*..0....n@+....}8.
0120	58 d8 c3 6d e7 79 ee ae 11 35 b7 bf 20 22 aa cb fc 3f 7e 00 74 11 56 74 01 0e 49 92 00 00 00 00	X..m.y...5..."...?~.t.Vt..I.....
0140	49 45 4e 44 ae 42 60 82	IEND.B`.