src/client/render/plain.cpp


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/*
Minetest
Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
Copyright (C) 2017 numzero, Lobachevskiy Vitaliy <numzer0@yandex.ru>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "plain.h"
#include "settings.h"

inline u32 scaledown(u32 coef, u32 size)
{
	return (size + coef - 1) / coef;
}

RenderingCorePlain::RenderingCorePlain(
	IrrlichtDevice *_device, Client *_client, Hud *_hud)
	: RenderingCore(_device, _client, _hud)
{
	scale = g_settings->getU16("undersampling");
}

void RenderingCorePlain::initTextures()
{
	if (scale <= 1)
		return;
	v2u32 size{scaledown(scale, screensize.X), scaledown(scale, screensize.Y)};
	lowres = driver->addRenderTargetTexture(
			size, "render_lowres", video::ECF_A8R8G8B8);
}

void RenderingCorePlain::clearTextures()
{
	if (scale <= 1)
		return;
	driver->removeTexture(lowres);
}

void RenderingCorePlain::beforeDraw()
{
	if (scale <= 1)
		return;
	driver->setRenderTarget(lowres, true, true, skycolor);
}

void RenderingCorePlain::upscale()
{
	if (scale <= 1)
		return;
	driver->setRenderTarget(0, true, true);
	v2u32 size{scaledown(scale, screensize.X), scaledown(scale, screensize.Y)};
	v2u32 dest_size{scale * size.X, scale * size.Y};
	driver->draw2DImage(lowres, core::rect<s32>(0, 0, dest_size.X, dest_size.Y),
			core::rect<s32>(0, 0, size.X, size.Y));
}

void RenderingCorePlain::drawAll()
{
	draw3D();
	drawPostFx();
	upscale();
	drawHUD();
}
-- interlocking/database.lua
-- saving the location of TCB's, their neighbors and their state
--[[

== THIS COMMENT IS PARTIALLY INCORRECT AND OUTDATED! ==

The interlocking system is based on track circuits.
Track circuit breaks must be manually set by the user. Signals must be assigned to track circuit breaks and to a direction(connid).
To simplify the whole system, there is no overlap.
== Trains ==
Trains always occupy certain track circuits. These are shown red in the signalbox view (TRAIN occupation entry).
== Database storage ==
The things that are actually saved are the Track Circuit Breaks. Each TCB holds a list of the TCBs that are adjacent in each direction.
TC occupation/state is then saved inside each (TCB,Direction) and held in sync across all TCBs adjacent to this one. If something should not be in sync,
all entries are merged to perform the most restrictive setup.
== Traverser function ==
To determine and update the list of neighboring TCBs, we need a traverser function.
It will start at one TCB in a specified direction (connid) and use get_adjacent_rail to crawl along the track. When encountering a turnout or a crossing,
it needs to branch(call itself recursively) to find all required TCBs. Those found TCBs are then saved in a list as tuples (TCB,Dir)
In the last step, they exchange their neighbors.
== TC states ==
A track circuit does not have a state as such, but has more or less a list of "reservations"
type can be one of these:
TRAIN See Trains obove
ROUTE Route set from a signal, but no train has yet passed that signal.
Not implemented (see note by reversible): OWNED - former ROUTE segments that a train has begun passing (train_id assigned)
		  - Space behind a train up to the next signal, when a TC is set as REVERSIBLE
Certain TCs can be marked as "allow call-on".
== Route setting: ==
Routes are set from a signal (the entry signal) to another signal facing the same direction (the exit signal)
Remember that signals are assigned to a TCB and a connid.
Whenever this is done, the following track circuits are set "reserved" by the train by saving the entry signal's ID:
- all TCs on the direct way of the route - set as ROUTE
Route setting fails whenever any TC that we want to set ROUTE to is already set ROUTE or TRAIN from another signal (except call-on, see below)
Apart from this, we need to set turnouts
- Turnouts on the track are set held as ROUTE
- Turnouts that purpose as flank protection are set held as FLANK (NOTE: left as an idea for later, because it's not clear how to do this properly without an engineer)
Note: In SimSig, it is possible to set a route into an still occupied section on the victoria line sim. (at the depot exit at seven sisters), although
	there are still segments set ahead of the first train passing, remaining from another route.
	Because our system will be able to remember "requested routes" and set them automatically once ready, this is not necessary here.
== Call-On/Multiple Trains ==
It will be necessary to join and split trains using call-on routes. A call-on route may be set when:
- there are no ROUTE reservations
- there are TRAIN reservations only inside TCs that have "allow call-on" set
== TC Properties ==
Note: Reversible property will not be implemented, assuming everything as non-rev.
This is sufficient to cover all use cases, and is done this way in reality.
	REVERSIBLE - Whether trains are allowed to reverse while on track circuit
	This property is supposed to be set for station tracks, where there is a signal at each end, and for sidings.
	It should in no case be set for TCs covering turnouts, or for main running lines.
	When a TC is not set as reversible, the OWNED status is cleared from the TC right after the train left it,
	to allow other trains to pass it.
	If it is set reversible, interlocking will keep the OWNED state behind the train up to the next signal, clearing it
	as soon as the train passes another signal or enters a non-reversible section.
CALL_ON_ALLOWED - Whether this TC being blocked (TRAIN or ROUTE) does not prevent shunt routes being set through this TC
== More notes ==
- It may not be possible to switch turnouts when their TC has any state entry

== Route releasing (TORR) ==
A train passing through a route happens as follows:
Route set from entry to exit signal
Train passes entry signal and enters first TC past the signal
-> Route from signal cleared (TCs remain locked)
-> ROUTE status of first TC past signal cleared
Train continues along the route.
Whenever train leaves a TC
-> Clearing any routes set from this TC outward recursively - see "Reversing problem"
Whenever train enters a TC
-> Clear route status from the just entered TC
Note that this prohibits by design that the train clears the route ahead of it.
== Reversing Problem ==
Encountered at the Royston simulation in SimSig. It is solved there by imposing a time limit on the set route. Call-on routes can somehow be set anyway.
Imagine this setup: (T=Train, R=Route, >=in_dir TCB)
    O-|  Royston P2 |-O
T->---|->RRR-|->RRR-|--
Train T enters from the left, the route is set to the right signal. But train is supposed to reverse here and stops this way:
    O-|  Royston P2 |-O
------|-TTTT-|->RRR-|--
The "Route" on the right is still set. Imposing a timeout here is a thing only professional engineers can determine, not an algorithm.
    O-|  Royston P2 |-O
<-T---|------|->RRR-|--
The train has left again, while route on the right is still set.
So, we have to clear the set route when the train has left the left TC.
This does not conflict with call-on routes, because both station tracks are set as "allow call-on"
Because none of the routes extends past any non-call-on sections, call-on route would be allowed here, even though the route
is locked in opposite direction at the time of routesetting.
Another case of this:
--TTT/--|->RRR--
The / here is a non-interlocked turnout (to a non-frequently used siding). For some reason, there is no exit node there,
so the route is set to the signal at the right end. The train is taking the exit to the siding and frees the TC, without ever
having touched the right TC.
]]--

local TRAVERSER_LIMIT = 1000


local ildb = {}

local track_circuit_breaks = {}
local track_sections = {}

-- Assignment of signals to TCBs
local signal_assignments = {}

-- track+direction -> signal position
local influence_points = {}

advtrains.interlocking.npr_rails = {}


function ildb.load(data)
	if not data then return end
	if data.tcbs then
		track_circuit_breaks = data.tcbs
	end
	if data.ts then
		track_sections = data.ts
	end
	if data.signalass then
		signal_assignments = data.signalass
	end
	if data.rs_locks then
		advtrains.interlocking.route.rte_locks = data.rs_locks
	end
	if data.rs_callbacks then
		advtrains.interlocking.route.rte_callbacks = data.rs_callbacks
	end
	if data.influence_points then
		influence_points = data.influence_points
	end
	if data.npr_rails then
		advtrains.interlocking.npr_rails = data.npr_rails
	end
end

function ildb.save()
	return {
		tcbs = track_circuit_breaks,
		ts=track_sections,
		signalass = signal_assignments,
		rs_locks = advtrains.interlocking.route.rte_locks,
		rs_callbacks = advtrains.interlocking.route.rte_callbacks,
		influence_points = influence_points,
		npr_rails = advtrains.interlocking.npr_rails,
	}
end

--
--[[
TCB data structure
{
[1] = { -- Variant: with adjacent TCs.
	ts_id = <id> -- ID of the assigned track section
	signal = <pos> -- optional: when set, routes can be set from this tcb/direction and signal
	-- aspect will be set accordingly.
	routeset = <index in routes> -- Route set from this signal. This is the entry that is cleared once
	-- train has passed the signal. (which will set the aspect to "danger" again)
	route_committed = <boolean> -- When setting/requesting a route, routetar will be set accordingly,
	-- while the signal still displays danger and nothing is written to the TCs
	-- As soon as the route can actually be set, all relevant TCs and turnouts are set and this field
	-- is set true, clearing the signal
	aspect = <asp> -- The aspect the signal should show. If this is nil, should show the most restrictive aspect (red)
	signal_name = <string> -- The human-readable name of the signal, only for documenting purposes
	routes = { <route definition> } -- a collection of routes from this signal
	route_auto = <boolean> -- When set, we will automatically re-set the route (designated by routeset)
},
[2] = { -- Variant: end of track-circuited area (initial state of TC)
	ts_id = nil, -- this is the indication for end_of_interlocking
	section_free = <boolean>, --this can be set by an exit node via mesecons or atlatc, 
	-- or from the tc formspec.
}
}

Track section
[id] = {
	name = "Some human-readable name"
	tc_breaks = { <signal specifier>,... } -- Bounding TC's (signal specifiers)
	-- Can be direct ends (auto-detected), conflicting routes or TCBs that are too far away from each other
	route = {
		origin = <signal>,  -- route origin
		entry = <sigd>,     -- supposed train entry point
		rsn = <string>,
		first = <bool>
	}
	route_post = {
		locks = {[n] = <pts>}
		next = <sigd>
	}
	-- Set whenever a route has been set through this TC. It saves the origin tcb id and side
	-- (=the origin signal). rsn is some description to be shown to the user
	-- first says whether to clear the routesetting status from the origin signal.
	-- locks contains the positions where locks are held by this ts.
	-- 'route' is cleared when train enters the section, while 'route_post' cleared when train leaves section.
	trains = {<id>, ...} -- Set whenever a train (or more) reside in this TC
}


Signal specifier (sigd) (a pair of TCB/Side):
{p = <pos>, s = <1/2>}

Signal Assignments: reverse lookup of signals assigned to TCBs
signal_assignments = {
[<signal pts>] = <sigd>
}
]]


--
function ildb.create_tcb(pos)
	local new_tcb = {
		[1] = {},
		[2] = {},
	}
	local pts = advtrains.roundfloorpts(pos)
	if not track_circuit_breaks[pts] then
		track_circuit_breaks[pts] = new_tcb
		return true
	else
		return false
	end
end

function ildb.get_tcb(pos)
	local pts = advtrains.roundfloorpts(pos)
	return track_circuit_breaks[pts]
end

function ildb.get_tcbs(sigd)
	local tcb = ildb.get_tcb(sigd.p)
	if not tcb then return nil end
	return tcb[sigd.s]
end


function ildb.create_ts(sigd)
	local tcbs = ildb.get_tcbs(sigd)
	local id = advtrains.random_id()