minetest.git - modified minetest for gpcfs purposes

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Diffstat (limited to 'src/script/cpp_api/s_item.h')

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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_index = Current index that the traverser has advanced so far checkpoints = table containing oncoming signals, in order of index { pos = position of the point index = where this is on the path speed = speed allowed to pass. nil = no effect callback = function(pos, id, train, index, speed, lzbdata) -- Function that determines what to do on the train in the moment it drives over that point. -- When spd==0, called instead when train has stopped in front -- nil = no effect lzbdata = {} -- Table of custom data filled in by approach callbacks -- Whenever an approach callback inserts an LZB checkpoint with changed lzbdata, -- all consecutive approach callbacks will see these passed as lzbdata table. udata = arbitrary user data, no official way to retrieve (do not use) } trav_lzbdata = currently active lzbdata table at traverser index } The LZB subsystem keeps track of "checkpoints" the train will pass in the future, and has two main tasks: 1. run approach callbacks, and run callbacks when passing LZB checkpoints 2. keep track of the permitted speed at checkpoints, and make sure that the train brakes accordingly To perform 2, it populates the train.path_speed table which is handled along with the path subsystem. This table is used in trainlogic.lua/train_step_b() and applied to the velocity calculations. Note: in contrast to node enter callbacks, which are called when the train passes the .5 index mark, LZB callbacks are executed on passing the .0 index mark! If an LZB checkpoint has speed 0, the train will still enter the node (the enter callback will be called), but will stop at the 0.9 index mark (for details, see SLOW_APPROACH in trainlogic.lua) The start point for the LZB traverser (and thus the first node that will receive an approach callback) is floor(train.index) + 1. This means, once the LZB checkpoint callback has fired, this path node will not receive any further approach callbacks for the same approach situation ]] 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 resolve_latest_lzbdata(ckp, index) local i = #ckp local ckpi while i>0 do ckpi = ckp[i] if ckpi.index <= index and ckpi.lzbdata then return ckpi.lzbdata end i=i-1 end return {} end local function look_ahead(id, train) local lzb = train.lzb if lzb.zero_checkpoint then -- if the checkpoints list contains a zero checkpoint, don't look ahead -- in order to not trigger approach callbacks on the wrong path return end local acc = advtrains.get_acceleration(train, 1) -- worst-case: the starting point is maximum speed local vel = train.max_speed or 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) -- worst case (don't use index_by_offset) local brake_i = atfloor(train.index + brakedst + params.BRAKE_SPACE) --atprint("LZB: looking ahead up to ", brake_i) --local aware_i = advtrains.path_get_index_by_offset(train, brake_i, AWARE_ZONE) local trav = lzb.trav_index -- retrieve latest lzbdata if not lzb.trav_lzbdata then lzb.trav_lzbdata = resolve_latest_lzbdata(lzb.checkpoints, trav) end if lzb.trav_lzbdata.off_track then --previous position was off track, do not scan any further end while trav <= brake_i and not lzb.zero_checkpoint do local pos = advtrains.path_get(train, trav) -- check offtrack if trav - 1 == train.path_trk_f then lzb.trav_lzbdata.off_track = true advtrains.lzb_add_checkpoint(train, trav - 1, 0, nil, lzb.trav_lzbdata) 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.trav_lzbdata) end trav = trav + 1 end lzb.trav_index = trav end advtrains.lzb_look_ahead = look_ahead local function call_runover_callbacks(id, train) if not train.lzb then return end local i = 1 local idx = atfloor(train.index) local ckp = train.lzb.checkpoints while ckp[i] do if ckp[i].index <= idx then --atprint("LZB: checkpoint run over: i=",ckp[i].index,"s=",ckp[i].speed,"p=",ckp[i].pos) -- call callback local it = ckp[i] if it.callback then it.callback(it.pos, id, train, it.index, it.speed, train.lzb.lzbdata) end -- note: lzbdata is always defined as look_ahead was called before table.remove(ckp, i) else i = i + 1 end end end -- Flood-fills train.path_speed, based on this checkpoint local function apply_checkpoint_to_path(train, checkpoint) if not checkpoint.speed then return end --atprint("LZB: applying checkpoint: i=",checkpoint.index,"s=",checkpoint.speed,"p=",checkpoint.pos) if checkpoint.speed == 0 then train.lzb.zero_checkpoint = true end -- make sure path exists until checkpoint local pos = advtrains.path_get(train, checkpoint.index) local brake_accel = advtrains.get_acceleration(train, 11) -- start with the checkpoint index at specified speed local index = checkpoint.index local p_speed -- speed in path_speed local c_speed = checkpoint.speed -- calculated speed at current index while true do p_speed = train.path_speed[index] if (p_speed and p_speed <= c_speed) or index < train.index then --we're done. train already slower than wanted at this position return end -- insert calculated target speed train.path_speed[index] = c_speed -- calculate c_speed at previous index advtrains.path_get(train, index-1) local eldist = train.path_dist[index] - train.path_dist[index-1] -- Calculate the start velocity the train would have if it had a end velocity of c_speed and accelerating with brake_accel, after a distance of eldist: -- v0² = v1² - 2*a*s c_speed = math.sqrt( (c_speed * c_speed) - (2 * brake_accel * eldist) ) index = index - 1 end end --[[ Distance needed to accelerate from v0 to v1 with constant acceleration a: v1 - v0 a / v1 - v0 \ 2 v1^2 - v0^2 s = v0 * ------- + - * | ------- | = ----------- a 2 \ a / 2*a ]] -- Removes all LZB checkpoints and restarts the traverser at the current train index function advtrains.lzb_invalidate(train)


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