line is drawn horizontally on the screen.
Over time, this line of cells evolves according to rules, with some cells
-switching on or off. Each new iteration is drawn below its predecessor, leading
-the screen to scroll vertically over time.
+switching on or off. Each new application of the rule to the universe is drawn
+on the screen as a new line directly below the previous generation's line,
+leading the screen to scroll vertically.
The rules which govern the time evolution of this system depend only on the
current state of a given cell and the state of its two immediate neighbors.
-Commandline flags are provided enabling the user to tweak attributes such as
-length and speed of simulation, cell size, rule number, colors, starting seed,
-and other attributes. For example, the screenshot below depicts Rule 73 with
-different colors than the Rule 110 screenshot. Like the Rule 110 screenshot, it
-uses `-cell-size 2` and seeds the simulation with only a single active cell.
+Commandline flags are provided which enable the user to tweak attributes such
+as length and speed of simulation, cell size, rule number, colors, starting
+seed, and other attributes. For example, the screenshot below depicts Rule 73
+with different colors than the Rule 110 screenshot. Like the Rule 110
+screenshot, it uses `-cell-size 2` and seeds the simulation with only a single
+active cell.
In situations where true randomness would lead to visually unappealing
-displays, this program provides random selection from curated lists. For
+displays, this program provides random selection from curated lists. As one
example, to avoid randomly selecting visually indistinguishable colors like
`dark red` and `brown` to depict on/off cells, the program includes a
pre-selected list of color pairs that complement each other and chooses
-randomly from this list when the `-random-color` flag is passed. Similarly, to
-avoid the visually uninteresting rules like rule 0, a rule which simply turns
-every cell off and keeps it off, the program includes a list of rulesets and
-starting seeds which are visually appealing, selecting randomly from this list
-when the `-random-rule` flag is passed.
+randomly from this list.
Status
that file. Note that the `Makefile` assumes a copy of the screenhack library
source code is located at `../screenhack/` relative to this directory.
-For assistance setting `$(DEFINES)` on non-FreeBSD platforms, consider
-downloading the XScreensaver source tarball, running `./configure` in the
-unpacked directory, and examining the resulting `config.h` file.
+For assistance setting `$(DEFINES)` in the `Makefile` on non-FreeBSD platforms,
+consider downloading the XScreensaver source tarball, running `./configure` in
+the unpacked directory, and examining the resulting `config.h` file.
Although WolframAutomata can integrate with XScreensaver, the presence of
XScreensaver is not strictly required. WolframAutomata will both build and
execute using only the included screenhack library.
+
+
+Command-Line Flags
+==================
+
+Whenever related options exist, such as the following two rule-selection
+options, the related options are listed in order of precedence.
+
+Where flags instruct the program to make random selections, these selections
+are re-randomized every time the simulation is reset, such as after a
+simulation completes or after resizing the window.
+
+
+CLI: Rule Selection
+-------------------
+
+If neither of the following two options are passed, rules are randomly selected
+from `curated_ruleset_list[]` in `WolframAutomata.c`.
+
+ - **`-true-random-rule`**: Select a rule completely at random, NOT randomly
+ from a curated list. Note that many rules are visually uninteresting.
+
+ - **`-rule N`**: Select a specific rule where `N` is a Wolfram number. Values
+ from 0-255 inclusive are valid.
+
+
+CLI: Simulation Seed
+--------------------
+
+The following seed related CLI flags apply only when using the
+`-true-random-rule` or `-rule N` flags. Without these flags, the program draws
+rules from `curated_ruleset_list[]` which also includes curated seeds, all of
+which override any seed related CLI flags.
+
+If the curated rule list is not in use and none of the following options are
+specified, the starting seed will contain randomly interspersed active/inactive
+cells at a 30/70, 50/50, or 70/30 ratio, itself also randomly selected.
+
+ - **`-seed-left`**: Seeds a single active cell on the left side of the
+ display. All other cells are inactive.
+
+ - **`-seed-center`**: As above, but in the center.
+
+ - **`-seed-right`**: As above, but on the right side.
+
+ - **`-seed-density N`**: Generates random seed with `N` percent active cells.
+
+
+CLI: Simulation Length
+----------------------
+
+If neither of the following two options are passed, the simulation runs as
+though `-length 5000` was passed.
+
+ - **`-random-length`**: A random length smaller than 10,000 generations but
+ large enough to fill the screen is selected.
+
+ - **`-length N`**: Request `N` generations be simulated on each run.
+
+Note that an upper limit of 10,000 generations is enforced in order to avoid
+`BadAlloc` errors from some X servers. For more details, read
+`WolframAutomata.c` starting around the comment, "The maximum number of
+generations is cell_size dependent. This is a soft limit and may be increased
+if ..."
+
+
+CLI: Simulation Speed
+---------------------
+
+If neither of the following two options are passed, the simulation runs as
+though `-delay 25000` was passed.
+
+ - **`-random-delay`**: A random delay is selected, but not truly random. For
+ more details, read `WolframAutomata.c` starting around the comment, "When
+ randomly setting the delay, the problem is to avoid ..."
+
+ - **`-delay N`**: Request `N` microsecond delay between each frame/generation
+ of the simulation. Note that this is only a request; XScreensaver reserves
+ the right to ignore requested values, and of course we execute at the mercy
+ of the kernel's scheduling. In practice, non-absurd values are reasonably
+ well respected.
+
+
+CLI: Cell Dimensions
+--------------------
+
+Individual cells may be displayed as any square number of pixels (e.g. 1x1,
+2x2, etc). Increasing the cell size may help with flickering on high DPI
+monitors displaying chaotic rulesets.
+
+If neither of the following two options are passed, the simulation behaves as
+though `-cell-size 2` was passed.
+
+ - **`-random-cell-size`**: Randomly selects 1, 2, 4, 8, 16, or 32 as the cell
+ size on each reset of the simulation.
+
+ - **`-cell-size N`**: Display each individual cell as an `N`x`N` square of
+ pixels on the screen.
+
+
+CLI: Color
+----------
+
+At the moment, the program does not allow the user to specify raw RGB values
+from the command line. Instead, color pairs are selected from `color_list[]`
+in `WolframAutomata.c` by specifying an index (starting from `0`) into this
+array. However, any RGB color the user desires may be added by creating new
+entries in that array (or editing existing entries) and recompiling.
+
+If the following CLI option is not passed, a random color selection is made
+from `color_list[]` at the start of each new simulation run.
+
+ - **`-color-index N`**: Select color pair `N` from `color_list[]` in
+ `WolframAutomata.c`.
+
+Note that the names provided as comments in `color_list[]` are X11 color names.
+
+
+CLI: Admiration
+---------------
+
+When the simulation reaches its end as determined by flags like `-length N` it
+will pause for a period of time, allowing the viewer to examine it without
+interference from scrolling. By default, this 'admiration window' is five
+seconds long.
+
+ - **`-admiration-delay N`**: At the end of a simulation, pause for `N`
+ seconds before resetting for the next simulation.
+
+
+XScreensaver Integration
+========================
+
+In addition to running as a standalone program, WolframAutomata can be
+integrated into the XScreensaver framework.
+
+To accomplish this integration, begin by installing and configuring
+XScreensaver via whatever method is appropriate for your operating system. The
+following instructions assume the filesystem paths used by FreeBSD packages and
+ports; your paths may differ. After XScreensaver installation, ensure all
+pertinent config files are created by running `xscreensaver-demo` and
+configuring XScreensaver for your system.
+
+After XScreensaver is configured and working on your system, ensure that
+WolframAutomata runs in standalone mode on your system. If you can `make clean run`
+in the `screensavers/hacks/WolframAutomata/` folder and see the hack's visual
+output, you're ready to move on.
+
+At this point, copy the hack into your XScreensaver hack directory. For
+example, with prerequisite steps spelled out:
+
+ git clone git://git.subgeniuskitty.com/screensavers
+ cd screensavers/hacks/WolframAutomata
+ make clean all
+ cp WolframAutomata /usr/local/bin/xscreensaver-hacks/wolframautomata
+
+Now create the file `wolframautomata.xml` wherever your system stores
+XScreensaver config files and populate it with the contents shown below. For
+example, on FreeBSD:
+
+ vi /usr/local/share/xscreensaver/config/wolframautomata.xml
+
+ <?xml version="1.0" encoding="ISO-8859-1"?>
+
+ <screensaver name="wolframautomata" _label="WolframAutomata">
+
+ <command arg="-root"/>
+
+ <string id="rule_number" _label="Rule number: " arg="-rule %" />
+ <boolean id="rnd_rule" _label="Random rule" arg-set="-random-rule" />
+
+ <string id="seed_density" _label="Seed density (%):" arg="-seed-density %" />
+ <boolean id="seed_left" _label="Seed left" arg-set="-seed-left" />
+ <boolean id="seed_center" _label="Seed center" arg-set="-seed-center" />
+ <boolean id="seed_right" _label="Seed right" arg-set="-seed-right" />
+
+ <string id="length" _label="Length (gen):" arg="-length %" />
+ <boolean id="rnd_length" _label="Random length" arg-set="-random-length" />
+
+ <string id="delay" _label="Delay (usec):" arg="-delay %" />
+ <boolean id="rnd_delay" _label="Random delay" arg-set="-random-delay" />
+
+ <string id="cell_size" _label="Cell size (px):" arg="-cell-size %" />
+ <boolean id="rnd_cellsize" _label="Random cell size" arg-set="-random-cell-size" />
+
+ <string id="color_index" _label="Color index (int):" arg="-color-index %" />
+
+ <string id="admiration" _label="Admiration (sec):" arg="-admiration-delay %" />
+
+ <_description>
+ Displays the time evolution of elementary cellular automata.
+
+ These automata consist of a line of cells, each of which may be either on or
+ off. To ensure every cell has neighbors, the two endpoints of the line connect
+ together, thereby forming a circular universe for the cells to inhabit. This
+ line is drawn horizontally on the screen.
+
+ Over time, this line of cells evolves according to rules, with some cells
+ switching on or off. Each new iteration is drawn below its predecessor,
+ leading the screen to scroll vertically over time.
+
+ The rules which govern the time evolution of this system depend only on the
+ current state of a given cell and the state of its two immediate neighbors.
+ These rules are formalized as Wolfram codes, where the code number is directly
+ convertible into a rule set.
+ </_description>
+ </screensaver>
+
+The next step integrates WolframAutomata into an individual user's XScreensaver
+config via the file `~/.xscreensaver`. If preferred, it could instead be done
+in the global XScreensaver config.
+
+In the `~/.xscreensaver` file, create a WolframAutomata entry under the
+`programs:` label in the same list as all the other hacks. Position in the
+list is irrelevant, but ensure you don't paste WolframAutomata's entry into the
+middle of pre-existing, multi-line entries. For context, the example below
+includes a multi-line entry, a GL entry and a plain entry. All that is needed
+is to insert the WolframAutomata line somewhere in the `programs:` list, as
+demonstrated.
+
+ vi ~/.xscreensaver
+
+ <snip>
+ programs: \
+ xplanet -vroot -wait 1 -timewarp 400 \
+ -label -origin moon \n\
+ GL: fireflies -root \n\
+ wolframautomata -root \n\
+ blitspin -root \n\
+ <snip>
+
+That's all. Now you can run `xscreensaver-demo` and select WolframAutomata just
+like any other hack.
+
+
+Screen Tearing
+==============
+
+Certain combinations of rules and display settings lead to full screen vertical
+scrolling of alternating light and dark pixels, or other difficult to display
+patterns. If your display doesn't include some type of vertical refresh
+synchronization, such output will look terrible.
+
+If stuck in this situation, changing the output of WolframAutomata to scroll
+horizontally may help, or simply increasing the cell size.
+
projects / screensavers / blobdiff