advtrains.git - Advtrains mod for minetest.

	Commit message (Expand)	Author	Age
*	Implement multi-occupation in detector.on_node table to finally fix collisions	orwell96	2017-10-25
*	Remove zip release files, move mod to root, exclude assets from Makefile (#92)	rubenwardy	2017-09-20

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-- lzb.lua
-- Enforced and/or automatic train override control, providing the on_train_approach callback

--[[
Documentation of train.lzb table
train.lzb = {
	trav = Current index that the traverser has advanced so far
	oncoming = table containing oncoming signals, in order of appearance on the path
		{
			pos = position of the point
			idx = where this is on the path
			spd = speed allowed to pass
			fun = function(pos, id, train, index, speed, lzbdata)
			-- Function that determines what to do on the train in the moment it drives over that point.
		}
}
each step, for every item in "oncoming", we need to determine the location to start braking (+ some safety margin)
and, if we passed this point for at least one of the items, initiate brake.
When speed has dropped below, say 3, decrease the margin to zero, so that trains actually stop at the signal IP.
The spd variable and travsht need to be updated on every aspect change. it's probably best to reset everything when any aspect changes
]]


local params = {
	BRAKE_SPACE = 10,
	AWARE_ZONE  = 50,

	ADD_STAND  =  2.5,
	ADD_SLOW   =  1.5,
	ADD_FAST   =  7,
	ZONE_ROLL  =  2,
	ZONE_HOLD  =  5, -- added on top of ZONE_ROLL
	ZONE_VSLOW =  3, -- When speed is <2, still allow accelerating

	DST_FACTOR =  1.5,

	SHUNT_SPEED_MAX = advtrains.SHUNT_SPEED_MAX,
}

function advtrains.set_lzb_param(par, val)
	if params[par] and tonumber(val) then
		params[par] = tonumber(val)
	else
		error("Inexistant param or not a number")
	end
end


local function look_ahead(id, train)
	
	local acc = advtrains.get_acceleration(train, 1)
	local vel = train.velocity
	local brakedst = ( -(vel*vel) / (2*acc) ) * params.DST_FACTOR
	
	local brake_i = advtrains.path_get_index_by_offset(train, train.index, brakedst + params.BRAKE_SPACE)
	--local aware_i = advtrains.path_get_index_by_offset(train, brake_i, AWARE_ZONE)
	
	local lzb = train.lzb
	local trav = lzb.trav
	
	--train.debug = lspd
	
	while trav <= brake_i do
		trav = trav + 1
		local pos = advtrains.path_get(train, trav)
		-- check offtrack
		if trav > train.path_trk_f then
			table.insert(lzb.oncoming, {
				pos = pos,
				idx = trav-1,
				spd = 0,
			})
		else
			-- run callbacks
			-- Note: those callbacks are defined in trainlogic.lua for consistency with the other node callbacks
			advtrains.tnc_call_approach_callback(pos, id, train, trav, lzb.data)