aboutsummaryrefslogtreecommitdiff
path: root/advtrains/locale
Commit message (Expand)AuthorAge
* Remove zip release files, move mod to root, exclude assets from Makefile (#92)rubenwardy2017-09-20
27'>27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626
--trainlogic.lua
--controls train entities stuff about connecting/disconnecting/colliding trains and other things

local print=function(t) minetest.log("action", t) minetest.chat_send_all(t) end

advtrains.train_accel_force=5--per second and divided by number of wagons
advtrains.train_brake_force=3--per second, not divided by number of wagons
advtrains.train_emerg_force=10--for emergency brakes(when going off track)

advtrains.audit_interval=10

advtrains.all_traintypes={}
function advtrains.register_train_type(name, drives_on, max_speed)
	advtrains.all_traintypes[name]={}
	advtrains.all_traintypes[name].drives_on=drives_on
	advtrains.all_traintypes[name].max_speed=max_speed or 10
end


advtrains.trains={}
advtrains.wagon_save={}

--load initially
advtrains.fpath=minetest.get_worldpath().."/advtrains"
local file, err = io.open(advtrains.fpath, "r")
if not file then
	local er=err or "Unknown Error"
	print("[advtrains]Failed loading advtrains save file "..er)
else
	local tbl = minetest.deserialize(file:read("*a"))
	if type(tbl) == "table" then
		advtrains.trains=tbl
	end
	file:close()
end
advtrains.fpath_ws=minetest.get_worldpath().."/advtrains_wagon_save"
local file, err = io.open(advtrains.fpath_ws, "r")
if not file then
	local er=err or "Unknown Error"
	print("[advtrains]Failed loading advtrains save file "..er)
else
	local tbl = minetest.deserialize(file:read("*a"))
	if type(tbl) == "table" then
		advtrains.wagon_save=tbl
	end
	file:close()
end


advtrains.save = function()
	--print("[advtrains]saving")
	advtrains.invalidate_all_paths()
	local datastr = minetest.serialize(advtrains.trains)
	if not datastr then
		minetest.log("error", "[advtrains] Failed to serialize train data!")
		return
	end
	local file, err = io.open(advtrains.fpath, "w")
	if err then
		return err
	end
	file:write(datastr)
	file:close()
	
	-- update wagon saves
	for _,wagon in pairs(minetest.luaentities) do
		if wagon.is_wagon and wagon.initialized then
			advtrains.wagon_save[wagon.unique_id]=advtrains.merge_tables(wagon)--so, will only copy non_metatable elements
		end
	end
	--cross out userdata
	for w_id, data in pairs(advtrains.wagon_save) do
		data.name=nil
		data.object=nil
		if data.driver then
			data.driver_name=data.driver:get_player_name()
			data.driver=nil
		else
			data.driver_name=nil
		end
	end
	--print(dump(advtrains.wagon_save))
	datastr = minetest.serialize(advtrains.wagon_save)
	if not datastr then
		minetest.log("error", "[advtrains] Failed to serialize train data!")
		return
	end
	file, err = io.open(advtrains.fpath_ws, "w")
	if err then
		return err
	end
	file:write(datastr)
	file:close()
	
	advtrains.save_trackdb()
end
minetest.register_on_shutdown(advtrains.save)

advtrains.save_and_audit_timer=advtrains.audit_interval
minetest.register_globalstep(function(dtime)
	advtrains.save_and_audit_timer=advtrains.save_and_audit_timer-dtime
	if advtrains.save_and_audit_timer<=0 then
		--print("[advtrains] audit step")
		--clean up orphaned trains
		for k,v in pairs(advtrains.trains) do
			--advtrains.update_trainpart_properties(k)
			if #v.trainparts==0 then
				advtrains.trains[k]=nil
			end
		end
		--save
		advtrains.save()
		advtrains.save_and_audit_timer=advtrains.audit_interval
	end
	--regular train step
	for k,v in pairs(advtrains.trains) do
		advtrains.train_step(k, v, dtime)
	end
end)

function advtrains.train_step(id, train, dtime)
	
	--TODO check for all vars to be present
	
	--if not train.last_pos then advtrains.trains[id]=nil return end
	
	if not advtrains.pathpredict(id, train) then 
		print("pathpredict failed(returned false)")
		train.velocity=0
		train.tarvelocity=0
		return
	end
	
	local path=advtrains.get_or_create_path(id, train)
	if not path then
		train.velocity=0
		train.tarvelocity=0
		print("train has no path for whatever reason")
		return 
	end
	--apply off-track handling:
	local front_off_track=train.max_index_on_track and train.index>train.max_index_on_track
	local back_off_track=train.min_index_on_track and (train.index-train.trainlen)<train.min_index_on_track
	if front_off_track and back_off_track then--allow movement in both directions
		if train.tarvelocity>1 then train.tarvelocity=1 end
		if train.tarvelocity<-1 then train.tarvelocity=-1 end
	elseif front_off_track then--allow movement only backward
		if train.tarvelocity>0 then train.tarvelocity=0 end
		if train.tarvelocity<-1 then train.tarvelocity=-1 end
	elseif back_off_track then--allow movement only forward
		if train.tarvelocity>1 then train.tarvelocity=1 end
		if train.tarvelocity<0 then train.tarvelocity=0 end
	end
	
	--move
	if not train.velocity then
		train.velocity=0
	end
	train.index=train.index and train.index+((train.velocity/(train.path_dist[math.floor(train.index)] or 1))*dtime) or 0
	--check for collisions by finding objects
	--front
	local search_radius=4
	
	local posfront=path[math.floor(train.index+1)]
	if posfront then
		local objrefs=minetest.get_objects_inside_radius(posfront, search_radius)
		for _,v in pairs(objrefs) do
			local le=v:get_luaentity()
			if le and le.is_wagon and le.initialized and le.train_id~=id then
				advtrains.try_connect_trains(id, le.train_id)
			end
		end
	end
	local posback=path[math.floor(train.index-(train.trainlen or 0)-1)]
	if posback then
		local objrefs=minetest.get_objects_inside_radius(posback, search_radius)
		for _,v in pairs(objrefs) do
			local le=v:get_luaentity()
			if le and le.is_wagon and le.initialized and le.train_id~=id then
				advtrains.try_connect_trains(id, le.train_id)
			end
		end
	end
	
	--check for any trainpart entities if they have been unloaded. do this only if train is near a player, to not spawn entities into unloaded areas
	train.check_trainpartload=(train.check_trainpartload or 0)-dtime
	local node_range=(math.max((minetest.setting_get("active_block_range") or 0),1)*16)
	if train.check_trainpartload<=0 and posfront and posback then
		--print(minetest.pos_to_string(posfront))
		local should_check=false
		for _,p in ipairs(minetest.get_connected_players()) do
			should_check=should_check or ((vector.distance(posfront, p:getpos())<node_range) and (vector.distance(posback, p:getpos())<node_range))
		end
		if should_check then
			--it is better to iterate luaentites only once
			--print("check_trainpartload")
			local found_uids={}
			for _,wagon in pairs(minetest.luaentities) do
				if wagon.is_wagon and wagon.initialized and wagon.train_id==id then
					if found_uids[wagon.unique_id] then
						--duplicate found, delete it
						if wagon.object then wagon.object:remove() end
					else
						found_uids[wagon.unique_id]=true
					end
				end
			end
			--print("found_uids: "..dump(found_uids))
			--now iterate trainparts and check. then cross them out to see if there are wagons over for any reason
			for pit, w_id in ipairs(train.trainparts) do
				if found_uids[w_id] then
					--print(w_id.." still loaded")
				elseif advtrains.wagon_save[w_id] then
					--print(w_id.." not loaded, but save available")
					--spawn a new and initialize it with the properties from wagon_save
					local le=minetest.env:add_entity(posfront, advtrains.wagon_save[w_id].entity_name):get_luaentity()
					for k,v in pairs(advtrains.wagon_save[w_id]) do
						le[k]=v
					end
					advtrains.wagon_save[w_id].name=nil
					advtrains.wagon_save[w_id].object=nil
				else
					print(w_id.." not loaded and no save available")
					--what the hell...
					table.remove(train.trainparts, pit)
				end
			end
		end
		train.check_trainpartload=1
	end
	
	
	--handle collided_with_env
	if train.recently_collided_with_env then
		train.tarvelocity=0
		if train.velocity==0 then
			train.recently_collided_with_env=false--reset status when stopped
		end
	end
	if train.locomotives_in_train==0 then
		train.tarvelocity=0
	end
	--apply tarvel(but with physics in mind!)
	if train.velocity~=train.tarvelocity then
		local applydiff=0
		local mass=#train.trainparts
		local diff=math.abs(train.tarvelocity)-math.abs(train.velocity)
		if diff>0 then--accelerating, force will be brought on only by locomotives.
			--print("accelerating with default force")
			applydiff=(math.min((advtrains.train_accel_force*train.locomotives_in_train*dtime)/mass, math.abs(diff)))
		else--decelerating
			if front_off_track or back_off_track or train.recently_collided_with_env then --every wagon has a brake, so not divided by mass.
				--print("braking with emergency force")
				applydiff=(math.min((advtrains.train_emerg_force*dtime), math.abs(diff)))
			else
				--print("braking with default force")
				applydiff=(math.min((advtrains.train_brake_force*dtime), math.abs(diff)))
			end
		end
		train.velocity=train.velocity+(applydiff*math.sign(train.tarvelocity-train.velocity))
	end
	
end

--the 'leader' concept has been overthrown, we won't rely on MT's "buggy object management"
--structure of train table:
--[[
trains={
	[train_id]={
		trainparts={
			[n]=wagon_id
		}
		path={path}
		velocity
		tarvelocity
		index
		trainlen
		path_inv_level
		last_pos       |
		last_dir       | for pathpredicting.
		no_connect_for_movements (index way counter for when not to connect again) TODO implement
	}
}
--a wagon itself has the following properties:
wagon={
	unique_id
	train_id
	pos_in_train (is index difference, including train_span stuff)
	pos_in_trainparts (is index in trainparts tabel of trains)
}
inherited by metatable:
wagon_proto={
	wagon_span
}
]]

--returns new id
function advtrains.create_new_train_at(pos, pos_prev, traintype)
	local newtrain_id=os.time()..os.clock()
	while advtrains.trains[newtrain_id] do newtrain_id=os.time()..os.clock() end--ensure uniqueness(will be unneccessary)
	
	advtrains.trains[newtrain_id]={}
	advtrains.trains[newtrain_id].last_pos=pos
	advtrains.trains[newtrain_id].last_pos_prev=pos_prev
	advtrains.trains[newtrain_id].traintype=traintype
	advtrains.trains[newtrain_id].tarvelocity=0
	advtrains.trains[newtrain_id].velocity=0
	advtrains.trains[newtrain_id].trainparts={}
	return newtrain_id
end

--returns false on failure. handle this case!
function advtrains.pathpredict(id, train)
	
	--print("pos ",x,y,z)
	--::rerun::
	if not train.index then train.index=0 end
	if not train.path or #train.path<2 then
		if not train.last_pos then
			--no chance to recover
			print("[advtrains]train hasn't saved last-pos, removing train.")
			advtrains.train[id]=nil
			return false
		end
		
		local node_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(train.last_pos), train.traintype)
		
		if node_ok==nil then
			--block not loaded, do nothing
			return nil
		elseif node_ok==false then
			print("[advtrains]no track here, (fail) removing train.")
			advtrains.trains[id]=nil
			return false
		end
		
		if not train.last_pos_prev then
			--no chance to recover
			print("[advtrains]train hasn't saved last-pos_prev, removing train.")
			advtrains.trains[id]=nil
			return false
		end
		
		local prevnode_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(train.last_pos_prev), train.traintype)
		
		if prevnode_ok==nil then
			--block not loaded, do nothing
			return nil
		elseif prevnode_ok==false then
			print("[advtrains]no track at prev, (fail) removing train.")
			advtrains.trains[id]=nil
			return false
		end
		
		train.index=(train.restore_add_index or 0)+(train.savedpos_off_track_index_offset or 0)
		--restore_add_index is set by save() to prevent trains hopping to next round index. should be between -0.5 and 0.5
		--savedpos_off_track_index_offset is set if train went off track. see below.
		train.path={}
		train.path_dist={}
		train.path[0]=train.last_pos
		train.path[-1]=train.last_pos_prev
		train.path_dist[-1]=vector.distance(train.last_pos, train.last_pos_prev)
	end
	
	local maxn=advtrains.maxN(train.path)
	while (maxn-train.index) < 2 do--pregenerate
		--print("[advtrains]maxn conway for ",maxn,minetest.pos_to_string(path[maxn]),maxn-1,minetest.pos_to_string(path[maxn-1]))
		local conway=advtrains.conway(train.path[maxn], train.path[maxn-1], train.traintype)
		if conway then
			train.path[maxn+1]=conway
			train.max_index_on_track=maxn
		else
			--do as if nothing has happened and preceed with path
			--but do not update max_index_on_track
			print("over-generating path max to index "..maxn+1)
			train.path[maxn+1]=vector.add(train.path[maxn], vector.subtract(train.path[maxn], train.path[maxn-1]))
		end
		train.path_dist[maxn]=vector.distance(train.path[maxn+1], train.path[maxn])
		maxn=advtrains.maxN(train.path)
	end
	
	local minn=advtrains.minN(train.path)
	while (train.index-minn) < (train.trainlen or 0) + 2 do --post_generate. has to be at least trainlen.
		--print("[advtrains]minn conway for ",minn,minetest.pos_to_string(path[minn]),minn+1,minetest.pos_to_string(path[minn+1]))
		local conway=advtrains.conway(train.path[minn], train.path[minn+1], train.traintype)
		if conway then
			train.path[minn-1]=conway
			train.min_index_on_track=minn
		else
			--do as if nothing has happened and preceed with path
			--but do not update min_index_on_track
			print("over-generating path min to index "..minn-1)
			train.path[minn-1]=vector.add(train.path[minn], vector.subtract(train.path[minn], train.path[minn+1]))
		end
		train.path_dist[minn-1]=vector.distance(train.path[minn], train.path[minn-1])
		minn=advtrains.minN(train.path)
	end
	if not train.min_index_on_track then train.min_index_on_track=0 end
	if not train.max_index_on_track then train.max_index_on_track=0 end
	
	--make pos/yaw available for possible recover calls
	if train.max_index_on_track<train.index then --whoops, train went too far. the saved position will be the last one that lies on a track, and savedpos_off_track_index_offset will hold how far to go from here
		train.savedpos_off_track_index_offset=train.index-train.max_index_on_track
		train.last_pos=train.path[train.max_index_on_track]
		train.last_pos_prev=train.path[train.max_index_on_track-1]
		--print("train is off-track (front), last positions kept at "..minetest.pos_to_string(train.last_pos).." / "..minetest.pos_to_string(train.last_pos_prev))
	elseif train.min_index_on_track+1>train.index then --whoops, train went even more far. same behavior
		train.savedpos_off_track_index_offset=train.index-train.min_index_on_track
		train.last_pos=train.path[train.min_index_on_track+1]
		train.last_pos_prev=train.path[train.min_index_on_track]
		--print("train is off-track (back), last positions kept at "..minetest.pos_to_string(train.last_pos).." / "..minetest.pos_to_string(train.last_pos_prev))
	else --regular case
		train.savedpos_off_track_index_offset=nil
		train.last_pos=train.path[math.floor(train.index+0.5)]
		train.last_pos_prev=train.path[math.floor(train.index-0.5)]
	end
	return train.path
end

function advtrains.get_or_create_path(id, train)
	if not train.path then return advtrains.pathpredict(id, train) end
	
	return train.path
end

function advtrains.add_wagon_to_train(wagon, train_id, index)
	local train=advtrains.trains[train_id]
	if index then
		table.insert(train.trainparts, index, wagon.unique_id)
	else
		table.insert(train.trainparts, wagon.unique_id)
	end
	--this is not the usual case!!!
	--we may set initialized because the wagon has no chance to step()
	wagon.initialized=true
	advtrains.update_trainpart_properties(train_id)
end
function advtrains.update_trainpart_properties(train_id, invert_flipstate)
	local train=advtrains.trains[train_id]
	local rel_pos=0
	local count_l=0
	for i, w_id in ipairs(train.trainparts) do
		local any_loaded=false
		for _,wagon in pairs(minetest.luaentities) do
			if wagon.is_wagon and wagon.initialized and wagon.unique_id==w_id then
				rel_pos=rel_pos+wagon.wagon_span
				wagon.train_id=train_id
				wagon.pos_in_train=rel_pos
				wagon.pos_in_trainparts=i
				wagon.old_velocity_vector=nil
				if wagon.is_locomotive then
					count_l=count_l+1
				end
				if invert_flipstate then
					wagon.wagon_flipped = not wagon.wagon_flipped
				end
				rel_pos=rel_pos+wagon.wagon_span
				any_loaded=true
			end
		end
		if not any_loaded then
			print("update_trainpart_properties wagon "..w_id.." not loaded, ignoring it.")
		end
	end
	train.trainlen=rel_pos
	train.locomotives_in_train=count_l
end

function advtrains.split_train_at_wagon(wagon)
	--get train
	local train=advtrains.trains[wagon.train_id]
	local pos_for_new_train=advtrains.get_or_create_path(wagon.train_id, train)[math.floor((train.index or 0)-wagon.pos_in_train-0.5)]
	local pos_for_new_train_prev=advtrains.get_or_create_path(wagon.train_id, train)[math.floor((train.index or 0)-wagon.pos_in_train-1.5)]
	
	--before doing anything, check if both are rails. else do not allow
	if not pos_for_new_train then
		print("split_train: pos_for_new_train not set")
		return false
	end
	local node_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(pos_for_new_train), train.traintype)
	if not node_ok then
		print("split_train: pos_for_new_train "..minetest.pos_to_string(advtrains.round_vector_floor_y(pos_for_new_train_prev)).." not loaded or is not a rail")
		return false
	end
	
	if not train.last_pos_prev then
		print("split_train: pos_for_new_train_prev not set")
		return false
	end
	
	local prevnode_ok=advtrains.get_rail_info_at(advtrains.round_vector_floor_y(pos_for_new_train), train.traintype)
	if not prevnode_ok then
		print("split_train: pos_for_new_train_prev "..minetest.pos_to_string(advtrains.round_vector_floor_y(pos_for_new_train_prev)).." not loaded or is not a rail")
		return false
	end
	
	--create subtrain
	local newtrain_id=advtrains.create_new_train_at(pos_for_new_train, pos_for_new_train_prev, train.traintype)
	local newtrain=advtrains.trains[newtrain_id]
	--insert all wagons to new train
	for k,v in ipairs(train.trainparts) do
		if k>=wagon.pos_in_trainparts then
			table.insert(newtrain.trainparts, v)
			train.trainparts[k]=nil
		end
	end
	--update train parts
	advtrains.update_trainpart_properties(wagon.train_id)--atm it still is the desierd id.
	advtrains.update_trainpart_properties(newtrain_id)
	train.tarvelocity=0
	newtrain.velocity=train.velocity
	newtrain.tarvelocity=0
end

--there are 4 cases:
--1/2. F<->R F<->R regular, put second train behind first
--->frontpos of first train will match backpos of second
--3.   F<->R R<->F flip one of these trains, take the other as new train
--->backpos's will match
--4.   R<->F F<->R flip one of these trains and take it as new parent
--->frontpos's will match
function advtrains.try_connect_trains(id1, id2)
	local train1=advtrains.trains[id1]
	local train2=advtrains.trains[id2]
	if not train1 or not train2 then return end
	if not train1.path or not train2.path then return end
	if train1.traintype~=train2.traintype then
		--TODO implement collision without connection
		return
	end
	if #train1.trainparts==0 or #train2.trainparts==0 then return end
	
	local frontpos1=train1.path[math.floor(train1.index+0.5)]
	local backpos1=train1.path[math.floor(train1.index-(train1.trainlen or 2)+0.5)]
	local frontpos2=train2.path[math.floor(train2.index+0.5)]
	local backpos2=train2.path[math.floor(train2.index-(train1.trainlen or 2)+0.5)]
	
	if not frontpos1 or not frontpos2 or not backpos1 or not backpos2 then return end
	
	--case 1 (first train is front)
	if vector.equals(frontpos2, backpos1) then
		advtrains.do_connect_trains(id1, id2)
	--case 2 (second train is front)
	elseif vector.equals(frontpos1, backpos2) then
		advtrains.do_connect_trains(id2, id1)
	--case 3 
	elseif vector.equals(backpos2, backpos1) then
		advtrains.invert_train(id2)
		advtrains.do_connect_trains(id1, id2)
	--case 4 
	elseif vector.equals(frontpos2, frontpos1) then
		advtrains.invert_train(id1)
		advtrains.do_connect_trains(id1, id2)
	end
end
function advtrains.do_connect_trains(first_id, second_id)
	local first_wagoncnt=#advtrains.trains[first_id].trainparts
	local second_wagoncnt=#advtrains.trains[second_id].trainparts
	
	for _,v in ipairs(advtrains.trains[second_id].trainparts) do
		table.insert(advtrains.trains[first_id].trainparts, v)
	end
	--kick it like physics (with mass being #wagons)
	local new_velocity=((advtrains.trains[first_id].velocity*first_wagoncnt)+(advtrains.trains[second_id].velocity*second_wagoncnt))/(first_wagoncnt+second_wagoncnt)
	advtrains.trains[second_id]=nil
	advtrains.update_trainpart_properties(first_id)
	advtrains.trains[first_id].velocity=new_velocity
	advtrains.trains[first_id].tarvelocity=0
end

function advtrains.invert_train(train_id)
	local train=advtrains.trains[train_id]
	
	local old_path=advtrains.get_or_create_path(train_id, train)
	train.path={}
	train.index=-train.index+train.trainlen
	train.velocity=-train.velocity
	train.tarvelocity=-train.tarvelocity
	for k,v in pairs(old_path) do
		train.path[-k]=v
	end
	local old_trainparts=train.trainparts
	train.trainparts={}
	for k,v in ipairs(old_trainparts) do
		table.insert(train.trainparts, 1, v)--notice insertion at first place
	end
	advtrains.update_trainpart_properties(train_id, true)
end

function advtrains.is_train_at_pos(pos)
	--print("istrainat: pos "..minetest.pos_to_string(pos))
	local checked_trains={}
	local objrefs=minetest.get_objects_inside_radius(pos, 2)
	for _,v in pairs(objrefs) do
		local le=v:get_luaentity()
		if le and le.is_wagon and le.initialized and le.train_id and not checked_trains[le.train_id] then
			--print("istrainat: checking "..le.train_id)
			checked_trains[le.train_id]=true
			local path=advtrains.get_or_create_path(le.train_id, le:train())
			if path then
				--print("has path")
				for i=math.floor(le:train().index-le:train().trainlen+0.5),math.floor(le:train().index+0.5) do
					if path[i] then
						--print("has pathitem "..i.." "..minetest.pos_to_string(path[i]))
						if vector.equals(advtrains.round_vector_floor_y(path[i]), pos) then
							return true
						end
					end
				end
			end
		end
	end
	return false
end
function advtrains.invalidate_all_paths()
	--print("invalidating all paths")
	for k,v in pairs(advtrains.trains) do
		if v.index then
			v.restore_add_index=v.index-math.floor(v.index+0.5)
		end
		v.path=nil
		v.index=nil
		v.min_index_on_track=nil
		v.max_index_on_track=nil
	end
end