Add simple text rendering library

6 files changed, 1276 insertions, 0 deletions

diff --git a/advtrains/init.lua b/advtrains/init.lua
index 083281e..18e1e37 100644
--- a/advtrains/init.lua
+++ b/advtrains/init.lua
@@ -200,6 +200,7 @@ advtrains.fpath=minetest.get_worldpath().."/advtrains"
 
 dofile(advtrains.modpath.."/path.lua")
 dofile(advtrains.modpath.."/trainlogic.lua")
+advtrains.textrender = dofile(advtrains.modpath.."/textrender.lua")
 dofile(advtrains.modpath.."/trainhud.lua")
 dofile(advtrains.modpath.."/trackplacer.lua")
 dofile(advtrains.modpath.."/copytool.lua")
diff --git a/advtrains/spec/textrender_spec.lua b/advtrains/spec/textrender_spec.lua
new file mode 100644
index 0000000..063d9ee
--- /dev/null
+++ b/advtrains/spec/textrender_spec.lua
@@ -0,0 +1,17 @@
+package.path = "../?.lua" .. package.path
+
+local tr = require("textrender")
+
+describe("string to unicode codepoint sequence converter", function()
+	local mbstoucs = tr.mbstoucs
+	it("should convert strings properly", function()
+		assert.same({0x61,0xe9,0x01d8}, mbstoucs("aéǘ"))
+	end)
+	it("should not convert invalid multibyte sequences", function()
+		local function assert_invalid(...)
+			assert.same({}, mbstoucs(string.char(...)))
+		end
+		assert_invalid(65, math.random(128,191), math.random(128,191))
+		assert_invalid(65, math.random(192,223))
+	end)
+end)
\ No newline at end of file
diff --git a/advtrains/textrender.lua b/advtrains/textrender.lua
new file mode 100644
index 0000000..f23cd3f
--- /dev/null
+++ b/advtrains/textrender.lua
@@ -0,0 +1,303 @@
+--[[ Simple text rendering (= texture generating) library
+Definitions:
+* A string ("str") refers to a regular Lua string
+* A codepoint ("cp") refers to a Unicode codepoint
+* A character ("char") refers to the smallest unit of rendering
+* A segment ("seg") refers to a unit of text that should not be broken across two or more lines unless the renderer is explicitly given the option to do so
+* A sequence ("seq") is a Lua table t where:
+  * Every element with a numeric index are of the same type
+  * Numeric indices are continuous positive integers starting from 1
+  * String indices can exist to indicate certain properties of the sequence
+  (Note that a "numeric index" refers to an index of a table that is a number. This includes floating-point numbers, inf, -inf, and NaN, if present)
+For simplicity, the above definitions may differ from that of Unicode
+Codepoints and characters differ in that characters can be composed out of multiple codepoints (e.g. the character "á" can be represented with U+00E1 or with a sequence of U+0061 followed by U+0301)
+
+Exposed API:
+* mbstoucs(str) a utility function that converts a string to a sequence of Unicode codepoints
+* texture_escape(str) a utility function that escapes the texture string
+]]
+
+-- Lookup tables
+local characters = {}
+do -- prevent LUT creation code from polluting the local environment
+	local function ensure_entry_exists(char)
+		if not characters[char] then
+			characters[char] = {}
+		end
+	end
+	local charwidth_lut = {}
+	local charwidth_ranges = {
+		[8] = {
+			0x20,0x7e, -- Latin
+			0xa0,0x052f, -- LGC
+		},
+	}
+	for k, v in pairs(charwidth_lut) do
+		ensure_entry_exists(k)
+		characters[k].width = v
+	end
+	for k, v in pairs(charwidth_ranges) do
+		for i = 1, #v, 2 do
+			for j = v[i], v[i+1] do
+				ensure_entry_exists(j)
+				if not characters[j].width then
+					characters[j].width = k
+				end
+			end
+		end
+	end
+	local charprops = {
+		can_break_lines = {0x20,},
+		force_linebreak = {0x0a,},
+	}
+	for k, v in pairs(charprops) do
+		for i = 1, #v do
+			local char = v[i]
+			ensure_entry_exists(char)
+			characters[char][k] = true
+		end
+	end
+end
+
+local function texture_escape(str)
+	return string.gsub(str, "[%[%()^:]", "\\%1")
+end
+
+-- Functions
+local function mbstoucs(str)
+	if type(str) ~= "string" then
+		return {}
+	end
+	local i = 1
+	local strlen = #str
+	local cps = {}
+	while i <= strlen do
+		local bytes = {string.byte(str, i, math.max(i+3, strlen))}
+		local nbytes
+		local codepoint
+		local msb = bytes[1]
+		if msb < 128 then
+			nbytes = 1
+		elseif msb >= 192 and bytes[2] and bytes[2] >= 128 and bytes[2] < 192 then
+			if msb < 224 then
+				nbytes = 2
+			elseif bytes[3] and bytes[3] >= 128 and bytes[3] < 192 then
+				if msb < 240 then
+					nbytes = 3
+				elseif msb < 148 and bytes[4] and bytes[4] >= 128 and bytes[4] < 192 then
+					nbytes = 4
+				end
+			end
+		end
+		if not nbytes then
+			return {} -- invalid MB character encountered
+		elseif nbytes == 1 then
+			codepoint = msb
+		else
+			codepoint = msb%(2^(7-nbytes))
+			for i = 2, nbytes do
+				codepoint = codepoint * 64 + bytes[i] - 128
+			end
+		end
+		cps[#cps+1] = codepoint
+		i = i + nbytes
+	end
+	return cps
+end
+
+local function basechar(char)
+	if type(char) == "table" then
+		return char[1]
+	else
+		return char
+	end
+end
+
+local function charwidth(char)
+	return (characters[basechar(char)] or {}).width
+end
+
+-- Splits the text into segments
+local function split_into_segments(cs)
+	local sl = {}
+	for i = 1, #cs do
+		local char = cs[i]
+		local props = characters[basechar(char)] or {}
+		local cwidth = charwidth(char)
+		if props.can_break_lines then
+			sl[#sl+1] = {bchar = char, bwidth = cwidth, width = cwidth, seq = {}, size = {}}
+		elseif props.force_linebreak then
+			sl[#sl+1] = {width = 0, seq = {}, size = {}}
+		else
+			if not sl[1] then
+				sl[1] = {width = cwidth, seq = {char}, size = {cwidth}}
+			else
+				seg = sl[#sl]
+				local seq, size = seg.seq, seg.size
+				seq[#seq+1] = char
+				size[#size+1] = (size[#size] or 0) + cwidth
+				seg.width = seg.width + cwidth
+			end
+		end
+	end
+	return sl
+end
+
+local function split_lines(cs, width, height, options)
+	local lines = {}
+	local nlines = options.lines
+	local lwidth = width+1 -- for newline for the first line
+	local wrap_overflow = options.wrap_overflow
+	local align = options.align
+	local sl = split_into_segments(cs)
+	for i = 1, #sl do
+		seg = sl[i]
+		local seq = seg.seq
+		if lwidth + seg.width <= width then
+			local line = lines[#lines]
+			line.width = (line.width or 0) + seg.width
+			if seg.bchar then
+				line[#line+1] = seg.bchar
+			end
+			local seq = seg.seq
+			for i = 1, #seq do
+				line[#line+1] = seq[i]
+			end
+		elseif lwidth > 0 then
+			-- create a new line
+			local line = seq
+			line.width = seg.size[#line]
+			lines[#lines+1] = line
+		else -- now we need to deal with segments longer than the given width
+			if wrap_overflow then
+				-- forcibly break the sequence
+				local st = seg.size
+				local ci = 1
+				local tw = 0
+				while ci <= #seq do
+					local l = {}
+					local j = ci
+					while j <= #seq and st[j]-tw <= width do
+						l[j-ci+1] = seq[j]
+						j = j+1
+					end
+					if l[1] then
+						l.width = st[j-1]-tw
+						lines[#lines+1] = l
+					end
+					ci = j
+				end
+			else
+				-- only add the sequence that will get rendered
+				local minx = align*(seq.width-width)
+				local maxx = minx+width
+				local l = {width = 0}
+				local st = seg.size
+				local i = 1
+				while st[i] and st[i] < minx do
+					i = i + 1
+				end
+				while st[i] and st[i] <= maxx do
+					l[#l+1] = seq[i]
+					l.width = l.width + charwidth(seq[i])
+				end
+				lines[#lines+1] = l
+			end
+		end
+		if #lines > nlines then
+			for i = nlines+1, #lines do
+				lines[i] = nil
+			end
+			break
+		end
+	end
+	return lines
+end
+
+local function cpstocs(cps)
+	return cps -- TODO: at least implement support for combining diacritics
+end
+
+local function check_options(width, height, options)
+	local w, h = tonumber(width), tonumber(height)
+	if not (w and h) then
+		return nil
+	end
+	if w < 8 or h < 18 then
+		return nil
+	end
+	local opt = options
+	if type(options) ~= "table" then
+		opt = {}
+	end
+	local ret = {}
+	-- check text alignment option
+	ret.align = math.min(math.max(tonumber(opt.align) or 0, 0),1)
+	-- check "wrap overflow text segment" option
+	ret.wrap_overflow = opt.wrap_overflow and true or false -- convert to boolean
+	-- check line count option
+	local maxlines = math.max(h/18)
+	ret.lines = math.min(maxlines, tonumber(opt.lines) or maxlines)
+	-- check text color option
+	ret.color = string.match(tostring(options.color) or "", "^#%x%x%x%x%x%x$") or "#000000"
+	return w, h, ret
+end
+
+local function get_char_texture(char)
+	if type(char) == "number" then
+		return string.format("(advtrains_unifont.png\\^[sheet\\:258x260\\:%d,%d)",
+			char%256+2,
+			math.floor(char/256+4)
+		)
+	end
+end
+
+local function render(str, ...)
+	local width, height, opts = check_options(...)
+	if not (width and height and opts) then
+		return nil
+	end
+	local lines = split_lines(cpstocs(mbstoucs(str)), width, height, opts)
+	local tst = {string.format("(([combine:%dx%d", width, height)}
+	local vpad = (height-18*#lines)/2
+	local align = opts.align
+	for i = 1, #lines do
+		local y = vpad+18*(i-1)
+		local line = lines[i]
+		if line.width then
+			local x = (width-line.width)*align
+			for i = 1, #line do
+				local char = line[i]
+				local cw = charwidth(char)
+				if cw > 0 then
+					tst[#tst+1] = string.format("%d,%d=%s", x, y, get_char_texture(char))
+					x = x + cw
+				end
+			end
+		end
+	end
+	return table.concat(tst,":")..string.format(")^[makealpha:0,0,0^[multiply:%s)", opts.color)
+end
+
+if minetest then
+	minetest.register_node("advtrains:textrender_demo",{
+		description = "Text rendering demo",
+		tiles = {"advtrains_hud_bg.png^[resize:128x128^[colorize:#0000ff^(advtrains_hud_bg.png^[resize:128x64)^"..render("Hello\n\n World", 128, 128, {color="#00ff00"})},
+		groups = {cracky=3, not_in_creative_inventory=1}
+	})
+	minetest.register_on_mods_loaded(function()
+		minetest.register_craft{
+			output = "advtrains:textrender_demo",
+			recipe = {
+				{"default:paper","default:paper","default:paper"},
+				{"default:paper","advtrains:hud_demo","default:paper"},
+				{"default:paper","default:paper","default:paper"},
+			}
+		}
+	end)
+end
+
+return {
+	mbstoucs = mbstoucs,
+	texture_escape = texture_escape,
+}
\ No newline at end of file
diff --git a/advtrains/textures/advtrains_unifont.png b/advtrains/textures/advtrains_unifont.png
new file mode 100644
index 0000000..6950dab
--- /dev/null
+++ b/advtrains/textures/advtrains_unifont.png
diff --git a/license_unifont.txt b/license_unifont.txt
new file mode 100644
index 0000000..4e8d77d
--- /dev/null
+++ b/license_unifont.txt
@@ -0,0 +1,953 @@
+
+License for all non-font source code in this package:
+
+   This package is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This package 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this package; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+
+
+License for font/plane00/jiskan16-plane00.hex and
+font/plane02/jiskan16-plane02.hex:
+
+     These two files are in the Public Domain.  They were created
+     from Public Domain BDF font files jiskan16-2004-1.bdf and
+     jiskan16-2000-2.bdf.
+
+
+License for font files except the jiskan16 files mentioned above
+are dual-licensed under the SIL Open Font License version 1.1,
+and under this GNU license:
+
+     All glyphs are released under the GNU General Public License
+     (GPL) version 2 or (at your option) a later version, with the
+     GNU font embedding exception:
+
+          ** GPL v2.0 license with font embedding exception:
+
+          As a special exception, if you create a document which
+          uses this font, and embed this font or unaltered portions
+          of this font into the document, this font does not by
+          itself cause the resulting document to be covered by
+          the GNU General Public License. This exception does not
+          however invalidate any other reasons why the document
+          might be covered by the GNU General Public License.
+          If you modify this font, you may extend this exception
+          to your version of the font, but you are not obligated
+          to do so. If you do not wish to do so, delete this
+          exception statement from your version.
+
+The SIL Open Font License is in the separate file "OFL-1.1.txt"
+in the Unifont distribution, and is also available with a FAQ at
+http://scripts.sil.org/OFL.  The license is copied below:
+
+     -----------------------------------------------------------
+     SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+     -----------------------------------------------------------
+
+     PREAMBLE
+     The goals of the Open Font License (OFL) are to stimulate worldwide
+     development of collaborative font projects, to support the font creation
+     efforts of academic and linguistic communities, and to provide a free and
+     open framework in which fonts may be shared and improved in partnership
+     with others.
+
+     The OFL allows the licensed fonts to be used, studied, modified and
+     redistributed freely as long as they are not sold by themselves. The
+     fonts, including any derivative works, can be bundled, embedded, 
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+     requirement for fonts to remain under this license does not apply
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+
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+
+     DISCLAIMER
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+     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
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+==============================================================================
+     
+License for doc/unifont.*:
+
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+
+GPL version 2 and GFDL version 1.3 are included below.
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+
+==============================================================================
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+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+                            NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 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 General Public License for more details.
+
+    You should have received a copy of the GNU 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.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
+
+==============================================================================
+
+
+                GNU Free Documentation License
+                 Version 1.3, 3 November 2008
+
+
+ Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+     <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+0. PREAMBLE
+
+The purpose of this License is to make a manual, textbook, or other
+functional and useful document "free" in the sense of freedom: to
+assure everyone the effective freedom to copy and redistribute it,
+with or without modifying it, either commercially or noncommercially.
+Secondarily, this License preserves for the author and publisher a way
+to get credit for their work, while not being considered responsible
+for modifications made by others.
+
+This License is a kind of "copyleft", which means that derivative
+works of the document must themselves be free in the same sense.  It
+complements the GNU General Public License, which is a copyleft
+license designed for free software.
+
+We have designed this License in order to use it for manuals for free
+software, because free software needs free documentation: a free
+program should come with manuals providing the same freedoms that the
+software does.  But this License is not limited to software manuals;
+it can be used for any textual work, regardless of subject matter or
+whether it is published as a printed book.  We recommend this License
+principally for works whose purpose is instruction or reference.
+
+
+1. APPLICABILITY AND DEFINITIONS
+
+This License applies to any manual or other work, in any medium, that
+contains a notice placed by the copyright holder saying it can be
+distributed under the terms of this License.  Such a notice grants a
+world-wide, royalty-free license, unlimited in duration, to use that
+work under the conditions stated herein.  The "Document", below,
+refers to any such manual or work.  Any member of the public is a
+licensee, and is addressed as "you".  You accept the license if you
+copy, modify or distribute the work in a way requiring permission
+under copyright law.
+
+A "Modified Version" of the Document means any work containing the
+Document or a portion of it, either copied verbatim, or with
+modifications and/or translated into another language.
+
+A "Secondary Section" is a named appendix or a front-matter section of
+the Document that deals exclusively with the relationship of the
+publishers or authors of the Document to the Document's overall
+subject (or to related matters) and contains nothing that could fall
+directly within that overall subject.  (Thus, if the Document is in
+part a textbook of mathematics, a Secondary Section may not explain
+any mathematics.)  The relationship could be a matter of historical
+connection with the subject or with related matters, or of legal,
+commercial, philosophical, ethical or political position regarding
+them.
+
+The "Invariant Sections" are certain Secondary Sections whose titles
+are designated, as being those of Invariant Sections, in the notice
+that says that the Document is released under this License.  If a
+section does not fit the above definition of Secondary then it is not
+allowed to be designated as Invariant.  The Document may contain zero
+Invariant Sections.  If the Document does not identify any Invariant
+Sections then there are none.
+
+The "Cover Texts" are certain short passages of text that are listed,
+as Front-Cover Texts or Back-Cover Texts, in the notice that says that
+the Document is released under this License.  A Front-Cover Text may
+be at most 5 words, and a Back-Cover Text may be at most 25 words.
+
+A "Transparent" copy of the Document means a machine-readable copy,
+represented in a format whose specification is available to the
+general public, that is suitable for revising the document
+straightforwardly with generic text editors or (for images composed of
+pixels) generic paint programs or (for drawings) some widely available
+drawing editor, and that is suitable for input to text formatters or
+for automatic translation to a variety of formats suitable for input
+to text formatters.  A copy made in an otherwise Transparent file
+format whose markup, or absence of markup, has been arranged to thwart
+or discourage subsequent modification by readers is not Transparent.
+An image format is not Transparent if used for any substantial amount
+of text.  A copy that is not "Transparent" is called "Opaque".
+
+Examples of suitable formats for Transparent copies include plain
+ASCII without markup, Texinfo input format, LaTeX input format, SGML
+or XML using a publicly available DTD, and standard-conforming simple
+HTML, PostScript or PDF designed for human modification.  Examples of
+transparent image formats include PNG, XCF and JPG.  Opaque formats
+include proprietary formats that can be read and edited only by
+proprietary word processors, SGML or XML for which the DTD and/or
+processing tools are not generally available, and the
+machine-generated HTML, PostScript or PDF produced by some word
+processors for output purposes only.
+
+The "Title Page" means, for a printed book, the title page itself,
+plus such following pages as are needed to hold, legibly, the material
+this License requires to appear in the title page.  For works in
+formats which do not have any title page as such, "Title Page" means
+the text near the most prominent appearance of the work's title,
+preceding the beginning of the body of the text.
+
+The "publisher" means any person or entity that distributes copies of
+the Document to the public.
+
+A section "Entitled XYZ" means a named subunit of the Document whose
+title either is precisely XYZ or contains XYZ in parentheses following
+text that translates XYZ in another language.  (Here XYZ stands for a
+specific section name mentioned below, such as "Acknowledgements",
+"Dedications", "Endorsements", or "History".)  To "Preserve the Title"
+of such a section when you modify the Document means that it remains a
+section "Entitled XYZ" according to this definition.
+
+The Document may include Warranty Disclaimers next to the notice which
+states that this License applies to the Document.  These Warranty
+Disclaimers are considered to be included by reference in this
+License, but only as regards disclaiming warranties: any other
+implication that these Warranty Disclaimers may have is void and has
+no effect on the meaning of this License.
+
+2. VERBATIM COPYING
+
+You may copy and distribute the Document in any medium, either
+commercially or noncommercially, provided that this License, the
+copyright notices, and the license notice saying this License applies
+to the Document are reproduced in all copies, and that you add no
+other conditions whatsoever to those of this License.  You may not use
+technical measures to obstruct or control the reading or further
+copying of the copies you make or distribute.  However, you may accept
+compensation in exchange for copies.  If you distribute a large enough
+number of copies you must also follow the conditions in section 3.
+
+You may also lend copies, under the same conditions stated above, and
+you may publicly display copies.
+
+
+3. COPYING IN QUANTITY
+
+If you publish printed copies (or copies in media that commonly have
+printed covers) of the Document, numbering more than 100, and the
+Document's license notice requires Cover Texts, you must enclose the
+copies in covers that carry, clearly and legibly, all these Cover
+Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
+the back cover.  Both covers must also clearly and legibly identify
+you as the publisher of these copies.  The front cover must present
+the full title with all words of the title equally prominent and
+visible.  You may add other material on the covers in addition.
+Copying with changes limited to the covers, as long as they preserve
+the title of the Document and satisfy these conditions, can be treated
+as verbatim copying in other respects.
+
+If the required texts for either cover are too voluminous to fit
+legibly, you should put the first ones listed (as many as fit
+reasonably) on the actual cover, and continue the rest onto adjacent
+pages.
+
+If you publish or distribute Opaque copies of the Document numbering
+more than 100, you must either include a machine-readable Transparent
+copy along with each Opaque copy, or state in or with each Opaque copy
+a computer-network location from which the general network-using
+public has access to download using public-standard network protocols
+a complete Transparent copy of the Document, free of added material.
+If you use the latter option, you must take reasonably prudent steps,
+when you begin distribution of Opaque copies in quantity, to ensure
+that this Transparent copy will remain thus accessible at the stated
+location until at least one year after the last time you distribute an
+Opaque copy (directly or through your agents or retailers) of that
+edition to the public.
+
+It is requested, but not required, that you contact the authors of the
+Document well before redistributing any large number of copies, to
+give them a chance to provide you with an updated version of the
+Document.
+
+
+4. MODIFICATIONS
+
+You may copy and distribute a Modified Version of the Document under
+the conditions of sections 2 and 3 above, provided that you release
+the Modified Version under precisely this License, with the Modified
+Version filling the role of the Document, thus licensing distribution
+and modification of the Modified Version to whoever possesses a copy
+of it.  In addition, you must do these things in the Modified Version:
+
+A. Use in the Title Page (and on the covers, if any) a title distinct
+   from that of the Document, and from those of previous versions
+   (which should, if there were any, be listed in the History section
+   of the Document).  You may use the same title as a previous version
+   if the original publisher of that version gives permission.
+B. List on the Title Page, as authors, one or more persons or entities
+   responsible for authorship of the modifications in the Modified
+   Version, together with at least five of the principal authors of the
+   Document (all of its principal authors, if it has fewer than five),
+   unless they release you from this requirement.
+C. State on the Title page the name of the publisher of the
+   Modified Version, as the publisher.
+D. Preserve all the copyright notices of the Document.
+E. Add an appropriate copyright notice for your modifications
+   adjacent to the other copyright notices.
+F. Include, immediately after the copyright notices, a license notice
+   giving the public permission to use the Modified Version under the
+   terms of this License, in the form shown in the Addendum below.
+G. Preserve in that license notice the full lists of Invariant Sections
+   and required Cover Texts given in the Document's license notice.
+H. Include an unaltered copy of this License.
+I. Preserve the section Entitled "History", Preserve its Title, and add
+   to it an item stating at least the title, year, new authors, and
+   publisher of the Modified Version as given on the Title Page.  If
+   there is no section Entitled "History" in the Document, create one
+   stating the title, year, authors, and publisher of the Document as
+   given on its Title Page, then add an item describing the Modified
+   Version as stated in the previous sentence.
+J. Preserve the network location, if any, given in the Document for
+   public access to a Transparent copy of the Document, and likewise
+   the network locations given in the Document for previous versions
+   it was based on.  These may be placed in the "History" section.
+   You may omit a network location for a work that was published at
+   least four years before the Document itself, or if the original
+   publisher of the version it refers to gives permission.
+K. For any section Entitled "Acknowledgements" or "Dedications",
+   Preserve the Title of the section, and preserve in the section all
+   the substance and tone of each of the contributor acknowledgements
+   and/or dedications given therein.
+L. Preserve all the Invariant Sections of the Document,
+   unaltered in their text and in their titles.  Section numbers
+   or the equivalent are not considered part of the section titles.
+M. Delete any section Entitled "Endorsements".  Such a section
+   may not be included in the Modified Version.
+N. Do not retitle any existing section to be Entitled "Endorsements"
+   or to conflict in title with any Invariant Section.
+O. Preserve any Warranty Disclaimers.
+
+If the Modified Version includes new front-matter sections or
+appendices that qualify as Secondary Sections and contain no material
+copied from the Document, you may at your option designate some or all
+of these sections as invariant.  To do this, add their titles to the
+list of Invariant Sections in the Modified Version's license notice.
+These titles must be distinct from any other section titles.
+
+You may add a section Entitled "Endorsements", provided it contains
+nothing but endorsements of your Modified Version by various
+parties--for example, statements of peer review or that the text has
+been approved by an organization as the authoritative definition of a
+standard.
+
+You may add a passage of up to five words as a Front-Cover Text, and a
+passage of up to 25 words as a Back-Cover Text, to the end of the list
+of Cover Texts in the Modified Version.  Only one passage of
+Front-Cover Text and one of Back-Cover Text may be added by (or
+through arrangements made by) any one entity.  If the Document already
+includes a cover text for the same cover, previously added by you or
+by arrangement made by the same entity you are acting on behalf of,
+you may not add another; but you may replace the old one, on explicit
+permission from the previous publisher that added the old one.
+
+The author(s) and publisher(s) of the Document do not by this License
+give permission to use their names for publicity for or to assert or
+imply endorsement of any Modified Version.
+
+
+5. COMBINING DOCUMENTS
+
+You may combine the Document with other documents released under this
+License, under the terms defined in section 4 above for modified
+versions, provided that you include in the combination all of the
+Invariant Sections of all of the original documents, unmodified, and
+list them all as Invariant Sections of your combined work in its
+license notice, and that you preserve all their Warranty Disclaimers.
+
+The combined work need only contain one copy of this License, and
+multiple identical Invariant Sections may be replaced with a single
+copy.  If there are multiple Invariant Sections with the same name but
+different contents, make the title of each such section unique by
+adding at the end of it, in parentheses, the name of the original
+author or publisher of that section if known, or else a unique number.
+Make the same adjustment to the section titles in the list of
+Invariant Sections in the license notice of the combined work.
+
+In the combination, you must combine any sections Entitled "History"
+in the various original documents, forming one section Entitled
+"History"; likewise combine any sections Entitled "Acknowledgements",
+and any sections Entitled "Dedications".  You must delete all sections
+Entitled "Endorsements".
+
+
+6. COLLECTIONS OF DOCUMENTS
+
+You may make a collection consisting of the Document and other
+documents released under this License, and replace the individual
+copies of this License in the various documents with a single copy
+that is included in the collection, provided that you follow the rules
+of this License for verbatim copying of each of the documents in all
+other respects.
+
+You may extract a single document from such a collection, and
+distribute it individually under this License, provided you insert a
+copy of this License into the extracted document, and follow this
+License in all other respects regarding verbatim copying of that
+document.
+
+
+7. AGGREGATION WITH INDEPENDENT WORKS
+
+A compilation of the Document or its derivatives with other separate
+and independent documents or works, in or on a volume of a storage or
+distribution medium, is called an "aggregate" if the copyright
+resulting from the compilation is not used to limit the legal rights
+of the compilation's users beyond what the individual works permit.
+When the Document is included in an aggregate, this License does not
+apply to the other works in the aggregate which are not themselves
+derivative works of the Document.
+
+If the Cover Text requirement of section 3 is applicable to these
+copies of the Document, then if the Document is less than one half of
+the entire aggregate, the Document's Cover Texts may be placed on
+covers that bracket the Document within the aggregate, or the
+electronic equivalent of covers if the Document is in electronic form.
+Otherwise they must appear on printed covers that bracket the whole
+aggregate.
+
+
+8. TRANSLATION
+
+Translation is considered a kind of modification, so you may
+distribute translations of the Document under the terms of section 4.
+Replacing Invariant Sections with translations requires special
+permission from their copyright holders, but you may include
+translations of some or all Invariant Sections in addition to the
+original versions of these Invariant Sections.  You may include a
+translation of this License, and all the license notices in the
+Document, and any Warranty Disclaimers, provided that you also include
+the original English version of this License and the original versions
+of those notices and disclaimers.  In case of a disagreement between
+the translation and the original version of this License or a notice
+or disclaimer, the original version will prevail.
+
+If a section in the Document is Entitled "Acknowledgements",
+"Dedications", or "History", the requirement (section 4) to Preserve
+its Title (section 1) will typically require changing the actual
+title.
+
+
+9. TERMINATION
+
+You may not copy, modify, sublicense, or distribute the Document
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense, or distribute it is void, and
+will automatically terminate your rights under this License.
+
+However, if you cease all violation of this License, then your license
+from a particular copyright holder is reinstated (a) provisionally,
+unless and until the copyright holder explicitly and finally
+terminates your license, and (b) permanently, if the copyright holder
+fails to notify you of the violation by some reasonable means prior to
+60 days after the cessation.
+
+Moreover, your license from a particular copyright holder is
+reinstated permanently if the copyright holder notifies you of the
+violation by some reasonable means, this is the first time you have
+received notice of violation of this License (for any work) from that
+copyright holder, and you cure the violation prior to 30 days after
+your receipt of the notice.
+
+Termination of your rights under this section does not terminate the
+licenses of parties who have received copies or rights from you under
+this License.  If your rights have been terminated and not permanently
+reinstated, receipt of a copy of some or all of the same material does
+not give you any rights to use it.
+
+
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+==============================================================================
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diff --git a/readme.txt b/readme.txt
index 05a5d5e..71f9ea7 100644
--- a/readme.txt
+++ b/readme.txt
@@ -6,6 +6,8 @@ For up-to-date information, visit https://advtrains.de/
 
 License of code: GNU AGPL version 3
 License of media: CC-BY-SA 3.0
+License exceptions:
+- advtrains/textures/advtrains_unifont.png: see license_unifont.txt
 
 (up to commit 1bb1d8, the license has been LGPL 2.1)