Difference between revisions of "Unicode"

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'''From Dictionary.com'''
'''Unicode''' is a character encoding standard, similar in spirit to [[ASCII]] but encoding vastly more characters. Whereas there are only 94 printable ASCII characters, there are literally hundreds of thousands of printable Unicode characters.
A 16-bit character set standard, designed and
maintained by the non-profit consortium Unicode Inc.


Originally Unicode was designed to be universal, unique, and
Roguelike games are historically console-based games that use characters to represent monsters, treasures, and maps. While some developers now prefer to use graphical [[tiles]] instead, Unicode allows roguelike games that use characters to represent things a much greater variety of visual representations.  
uniform, i.e., the code was to cover all major modern written
languages (universal), each character was to have exactly one
encoding (unique), and each character was to be represented by
a fixed width in bits (uniform).


Parallel to the development of Unicode an [[ISO]]/[[IEC]]
Unicode is derived from a host of earlier character encodings, each of which added some characters to the ASCII set, but most of which added no more than 128 additional characters by using the high bit (8th bit).  While ASCII with its 94 printable characters was a reasonable way to represent English text, these high-bit encodings, or code pages, each of which was ASCII plus some selected characters, were a reasonably complete way to encode one, two, or a few additional languages each. But it wouldn't work if you took the high-bit encoding that handled, say, Arabic characters and tried to use it to represent German text, which requires Roman characters with umlauts.
standard was being worked on that put a large emphasis on
being compatible with existing character codes such as [[ASCII]]
or [[ISO Latin 1]]. To avoid having two competing 16-bit
standards, in 1992 the two teams compromised to define a
common character code standard, known both as Unicode and
BMP.


Since the merger the character codes are the same but the two
The trouble with these extensions was that there were so many to choose from.  While characters 0-127 (which were encoded by ASCII) were always the same from computer to computer, characters 128-255 (which were encoded by whatever high-bit encoding was in use locally) were not.  Assumptions about code pages being the same led to strange gibberish being displayed rather than the correct characters.  
standards are not identical. The [[ISO]]/[[IEC]] standard covers only
coding while Unicode includes additional specifications that
help implementation.


Unicode is not a glyph encoding. The same character can be
Unicode is an attempt to resolve this once and for all by using a larger character set of 1,114,112 (2^20 + 2^16) code points, allowing it to map all known human glyphs into one consistent character set. Nearly 10% of those code points are already assigned.  Any Unicode character can be represented with 21 bits, although depending on what 'encoding' your local system uses the actual number of bits devoted to representing a particular character may be more or less. The first 127 code points, like the first 127 code points of all the ISO standards, are the same as in ASCII. 
displayed as a variety of [[glyphs]], depending not only on the
 
font and style, but also on the adjacent characters. A
The majority of the most useful characters are encoded in the first 65536 locations of Unicode, which is called the Basic Multilingual Plane.  Since this is the number of different bit patterns that can be represented with two bytes, some programming languages (such as Java) use two bytes as their basic character type. 
sequence of characters can be displayed as a single glyph or a
 
character can be displayed as a sequence of [[glyphs]]. Which
== Unicode in Roguelikes ==
will be the case, is often font dependent.
 
Many roguelikes, including [[NetHack]], have historically included options to take advantage of high-bit encodings to get extra symbols, allowing them to draw walls with lines rather than # marks.  But if a different code page than the expected one happens to be loaded, the results can be humourous since the code points that the program expects to contain lines may contain, say, Arabic or Cyrillic characters instead. This can be seen when NetHack's IBMgraphics display is played with DOS code page 850.
 
Modern terminal programs, however, mostly use Unicode characters now rather than the various earlier code pages, so using Unicode characters allows roguelikes to access these special glyphs in a platform independent manner. It also allows for the use of glyphs from typically eastern languages (which may be ideal for those who can read those glyphs, as entire words may be represented as a single character).
 
Unfortunately, Unicode, by its "embrace every known glyph" mentality, can't guarantee that the font that you are using actually has the glyph defined.
 
It is surprisingly difficult to get a C program to use Unicode characters effectively in combination with a curses display, mostly due to inadequate documentation of the requirements.  These requirements are listed at the page on [[Ncursesw]].
 
== Roguelikes using Unicode==
Roguelikes that use Unicode are:
* [[ChessRogue]]
* [[Legerdemain]]
* [[Dungeon Crawl Stone Soup]]
* [[Neon]]
 
== External links ==
 
* [https://github.com/globalcitizen/zomia/blob/master/USEFUL-UNICODE.md Useful Unicode characters for Roguelikes] (c/[[Zomia]] .. not hosted here as Wikimedia breaks many Unicode characters .. contributions welcome)
* [http://en.wikipedia.org/wiki/Unicode Everything you wanted to know about Unicode but were afraid to ask]
* [http://www.joelonsoftware.com/articles/Unicode.html The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)]
 
[[category:articles]]

Latest revision as of 07:53, 22 September 2016

Unicode is a character encoding standard, similar in spirit to ASCII but encoding vastly more characters. Whereas there are only 94 printable ASCII characters, there are literally hundreds of thousands of printable Unicode characters.

Roguelike games are historically console-based games that use characters to represent monsters, treasures, and maps. While some developers now prefer to use graphical tiles instead, Unicode allows roguelike games that use characters to represent things a much greater variety of visual representations.

Unicode is derived from a host of earlier character encodings, each of which added some characters to the ASCII set, but most of which added no more than 128 additional characters by using the high bit (8th bit). While ASCII with its 94 printable characters was a reasonable way to represent English text, these high-bit encodings, or code pages, each of which was ASCII plus some selected characters, were a reasonably complete way to encode one, two, or a few additional languages each. But it wouldn't work if you took the high-bit encoding that handled, say, Arabic characters and tried to use it to represent German text, which requires Roman characters with umlauts.

The trouble with these extensions was that there were so many to choose from. While characters 0-127 (which were encoded by ASCII) were always the same from computer to computer, characters 128-255 (which were encoded by whatever high-bit encoding was in use locally) were not. Assumptions about code pages being the same led to strange gibberish being displayed rather than the correct characters.

Unicode is an attempt to resolve this once and for all by using a larger character set of 1,114,112 (2^20 + 2^16) code points, allowing it to map all known human glyphs into one consistent character set. Nearly 10% of those code points are already assigned. Any Unicode character can be represented with 21 bits, although depending on what 'encoding' your local system uses the actual number of bits devoted to representing a particular character may be more or less. The first 127 code points, like the first 127 code points of all the ISO standards, are the same as in ASCII.

The majority of the most useful characters are encoded in the first 65536 locations of Unicode, which is called the Basic Multilingual Plane. Since this is the number of different bit patterns that can be represented with two bytes, some programming languages (such as Java) use two bytes as their basic character type.

Unicode in Roguelikes

Many roguelikes, including NetHack, have historically included options to take advantage of high-bit encodings to get extra symbols, allowing them to draw walls with lines rather than # marks. But if a different code page than the expected one happens to be loaded, the results can be humourous since the code points that the program expects to contain lines may contain, say, Arabic or Cyrillic characters instead. This can be seen when NetHack's IBMgraphics display is played with DOS code page 850.

Modern terminal programs, however, mostly use Unicode characters now rather than the various earlier code pages, so using Unicode characters allows roguelikes to access these special glyphs in a platform independent manner. It also allows for the use of glyphs from typically eastern languages (which may be ideal for those who can read those glyphs, as entire words may be represented as a single character).

Unfortunately, Unicode, by its "embrace every known glyph" mentality, can't guarantee that the font that you are using actually has the glyph defined.

It is surprisingly difficult to get a C program to use Unicode characters effectively in combination with a curses display, mostly due to inadequate documentation of the requirements. These requirements are listed at the page on Ncursesw.

Roguelikes using Unicode

Roguelikes that use Unicode are:

External links

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