LucidLife Help

Contents

  1. Introduction to Conway's Life
  2. Introduction to LucidLife
  3. The Pattern Archive
  4. Anatomy of the Main Window
  5. Usage
    1. Moving Around
    2. Zooming
    3. Drawing
    4. Cut and Paste
    5. Running
    6. Changing Speed
    7. File Handling
  6. Menu Reference
    1. File
    2. View
    3. Edit
    4. Run
    5. Help
  7. Configuring LucidLife
  8. Keybindings


1. Introduction to Conway's Life

Conway's Life is a form of artificial life (specifically, a cellular automaton)--one of the simplest there is. There are only a few rules:

  1. The game is played on a rectangular grid, where each cell is either alive or dead.
  2. Each generation is computed from the state of the previous generation, using rules 3 and 4:
  3. A live cell with 2 or 3 live neighbors (adjacent cells, including diagonals) lives on. Otherwise it dies.
  4. A dead cell with exactly 3 live neighbors comes to life.

That's all there is to it. Yet fascinating behavior arises from these simple rules. Gliders, for instance.

[Glider]

It turns out, if you take the little five-cell shape to the left and apply the rules of Life to it, it glides diagonally across the grid. That is, it transforms in such a way that it reproduces itself at an offset every four generations. No one invented gliders. They just happen. In fact, draw some random cells in a Life program and hit "start," and it's a good chance you'll see gliders form spontaneously. This is just the beginning: Conway's Life has a whole menagerie of recurring patterns.


Much more detailed introductions to Conway's Life are available on the web. Here are a few links worth following:


[Pulsar]

2. Introduction to LucidLife

You can play Conway's Life with nothing more than a pencil and a sheet of graph paper, but it's a lot faster to use a computer. That's where LucidLife comes in. It provides you with a scrolling 1 million x 1 million cell grid, which should be enough space for even the most complex patterns, and an optimized algorithm which can run up to hundreds of generations per second. At any time, you can save the contents of the grid to a file for later use. There are also a number of preset patterns bundled with the application.

For Life newbies, getting started is easy. Scribble generously on the Life canvas, then push the play button. You'll see various "still lifes" (unchanging shapes), blinkers, and gliders coalesce out of the ensuing chaos. If you're lucky you might see a lightweight spaceship or a pulsar. Now try to figure out why it happens!

Once you've experimented on your own for a while, you may want to explore what others have created in the Life Pattern Archive.


[A pattern called 'Max']

3. The Pattern Archive

LucidLife comes with the Life Pattern Archive, a public-domain collection amassed by Alan Hensel. After installation, the patterns are available from LucidLife in a sidebar on the main window. Another collection, Jason Summers' JSLife, is also available and can be selected as an option. The Life Pattern Archive has a good range of patterns from simple to complex; JSLife contains more esoteric, unusual, and recently-discovered patterns.

Most of the patterns have descriptions provided by their authors, which you can read after loading by selecting File->Description. If you get lost in the terminology (rakes, sawtooths, corderships...), the online Life Lexicon will clear things up.

A typical Life pattern explodes chaotically, then gradually settles down into small groups of predictable cells. However, Life enthusiasts have engineered patterns that are anything but typical, and most of the included files fall into that category. There are fleets of ships, glider guns, complex oscillators, puffer trains, breeders that grow at quadratic speed, patterns that build other patterns, and perhaps the most anomalous pattern of all, "Max" (pictured at left). To get an idea of just how delicately balanced Max is, let it run for awhile, then erase one little dot in the middle.

Then there are the computational patterns, of which perhaps the most impressive is a functional (though slow) prime number sieve. As it turns out, Life is Turing-Complete: given a large enough grid and enough time, it can perform any computation that a modern computer could.

Here are a few of the author's current favorites:

LPA/Breeders/"Breeder 4"
One of the more unusual breeders: it generates a zigzagging grid of gliders.
LPA/Math and CS/"Primes"
Produces a westward stream of spaceships representing prime numbers. It's a real puzzle to try to figure out how this works.
LPA/Math and CS/"Unit Cell"
A 500x500-cell cell, duplicating the rules of a life on a larger scale.
JSLife/Builders/"SS Factory"
A spaceship factory. Complex machinery funnels four streams of gliders into the middle of the pattern, where they synthesize a fleet of 2c/5 spaceships.
JSLife/Odds & Ends/"Shuttle"
A corridor of gliders shuttles a spaceship back and forth. It's just cute.

For more details on the contents of the Life Pattern Archive, see Alan Hensel's notes.


4. Anatomy of the Main Window

The LucidLife main window consists of a scrollable viewport in the middle, a menubar and toolbar at top, a scrollable sidebar at the left, and a status bar at the bottom. Many of these components can be disabled from the "View" menu, and a fullscreen mode is available.


[Main Window]


Viewport
The main display of LucidLife is a scrolling viewport on the 1 million x 1 million Life grid. At startup, it is centered on the middle of the world, which has the coordinates (0,0).

Toolbar
As well as buttons corresponding to the most frequently used menu items, at the far right of the toolbar is a slider which adjusts the speed at which the game runs. The number above it indicates the present speed in generations per second. The maximum speed may be set in the Preferences dialog.

Sidebar
The Sidebar lists the contents of the currently chosen pattern collection. Simply click on a pattern title to load the file. Scroll through the list of patterns using the scrollbar or your mouse wheel. As a shortcut for File->Change Pattern Collection, you can click on the "Patterns" list header to choose a new collection.

Some patterns are sorted into sub-directories--in fact, the included collections (Life Pattern Archive and JSLife) are entirely hierarchical. Directories are displayed with trailing slashes. Click on a directory to display its contents in a clickable list below the main sidebar.

Status Bar
The status bar displays various useful bits of information. On the left, it shows the coordinates of the cell where the mouse is hovering, or of the top-left of the display while scrolling.. On the right, labeled "Tick" and "Population", are the current generation number and the current live cell count. The middle is reserved for messages to the user.

5. Usage

5.1. Moving Around

In addition to the visible scrollbars, there are a number of other ways to move the Life viewport:

Some Life patterns (e.g. Jaws, Catacryst) are very sparse--you may not even see any cells in the viewport when you first load them. For these, the View->Find Active Cells command is useful. It will locate an area containing live cells and center on it, preferring active regions to those which have become stable (still life) or oscillatory.

5.2. Zooming

Zoom operations are available from the "View" menu and from the magnifying glasses in the toolbar. At 1:1, the viewport is zoomed all the way out, so that one blue pixel represents one live cell. You can zoom in up to 16:1, which makes operations like drawing much easier. At zoom levels 4:1 and up, a visual grid is drawn to clearly distinguish individual cells.

Zooming may also be accomplished by holding control while using the mouse wheel.

5.3. Drawing

When the Draw () tool is selected, left-click on the grid to toggle a cell between alive and dead. Drag the mouse to continue drawing or continue erasing cells. If you drag to the edge of the viewport, it will scroll with you.

5.4. Cut and Paste

LucidLife supports block cut-and-paste of pattern cells. To select a block of cells, left click on one corner of the block while using the Select ( ) tool, or holding <shift> key, then drag to the opposite corner. If you drag to the edge, the viewport will scroll with you, so you can select as large an area as you like.

The selection can then be cut/copied and pasted via the commands in the "Edit" menu (or by using the standard Ctrl-X, Ctrl-C, and Ctrl-V keystrokes). After choosing "Paste", a highlighted rectangle will appear as you move over the grid. Left-click when the rectangle is located where you want to paste. For convenience, Unix-style pasting is also allowed: instead of using the Paste command, simply middle-click on the upper-left corner of the desired region.

If there is a currently selected region when you paste, it will be implicitly copied and used in place of the copy buffer.

Note: LucidLife pasting is "transparent"--only live cells are copied. In other words, empty cells in the source region will not overwrite live cells in the target region.

5.5. Running

Start the pattern by clicking the play button on the toolbar. Click the button again to stop. Note that most operations are still available while the pattern is running. In particular, you can draw and cut-and-paste in the middle of a running pattern. Of course, a lone plotted cell will quickly die out!

There are two other ways to advance the pattern: Run->Step (the green arrow in the toolbar) to advance by one generation, and Run->Jump to jump ahead to a particular generation as quickly as possible.

5.6. Changing Speed

Speed is adjustable, and is set in generations per second. You can adjust speed gradually using the ',' and '.' keys, or directly using the Run->Speed dialog or the slider on the toolbar.

The program will start to drop frames if it finds itself falling behind---that is, the next generation will be computed, but the screen will not update during that tick. This greatly improves performance, especially if you don't have 2D acceleration on your video card, but it makes the animation less smooth. If you want to temporarily disable frame skipping, deselect the "skip frames" check box in the Preferences dialog.

5.7. File Handling

All of the standard commands are available from the File menu: New, Open, Save, and Save As. In addition, the Revert command (R) provides an easy way to "rewind" a pattern back to its saved state. Only one pattern file can be loaded at a time.

You can specify a pattern file on the command line to load it at start-up. If you specify a directory on the command line, it will be set as the pattern collection for the sidebar.

LucidLife supports a number of different pattern file formats, including RLE, Life 1.05, Life 1.06, and XLife. It also has a native format, GLF. Format is auto-detected when loading, while the "Save As" dialog allows you to choose format from a pull-down list. All file formats support a textual pattern description, which can be viewed and/or edited via the File->Description command.

LucidLife only supports the classic rules of life: survive with 2 or 3 neighbors, birth with 3 neighbors. Thus, any special rules directives in pattern files will be ignored.

"Structured" XLife files (containing include directives and/or sub-patterns) are not currently supported. This includes many of the patterns bundled with the latest XLife.


6. Menu Reference

6.1. File Menu

File->New
Start a new file, clearing the Life grid.
File->Open
Load a pattern file. The Open dialog defaults to the directory of the current pattern collection, so that you can browse the collection even if you've disabled the sidebar.
File->Revert
Reload the current pattern from disk. This provides an easy way to revert a pattern back to its original state, provided it has a file associated with it.
File->Save
Save the contents of the grid and description to a pattern file.
File->Save As
Save with a new filename.
File->Description
View and/or edit the pattern description. If you load a new pattern file while the description dialog is active, it will automatically update.
File->Change Pattern Collection
Choose a different collection of Life patterns. You can select one of several included collections, or simply pick a directory: any files in the directory with recognized extensions (.glf, .rle, .lif, .l) will be listed in the sidebar, as will any sub-directories. This also sets the default starting directory for the File->Open dialog, so that you can easily load files from the collection when the sidebar is hidden. .
Recent files
The five most recently accessed pattern files are listed near the bottom of the File menu for quick loading.
File->Quit
Exit LucidLife.

6.2. View Menu

View->Zoom In
Zoom in by a factor of 2.
View->Zoom Out
Zoom out by a factor of 2.
View->Zoom (submenu)
Choose a particular zoom level.
View->Recenter
Recenter the viewport on the middle of the world (0,0).
View->Find Active Cells
Find a region containing live cells and center on it. LucidLife will try to locate an active area of the grid, i.e., one where cells are neither stable nor oscillatory. Failing that, it will locate a region of oscillating cells, and failing that, stable ones.
View->Show Toolbar
View->Show Sidebar
View->Show Scrollbars
View->Show Status Bar
These checkboxes allow you to enable or disable various components of the main window.
View->Fullscreen
Check this item to put LucidLife in fullscreen mode. The main window will enlarge to fill the screen and all components except for the Life viewport and the status bar will be turned off, including menus (use keyboard accelerators to control the application). If this function does not work properly, it is probably because your window manager doesn't support EWMH.

6.3. Edit Menu

All of these commands (except for Edit->Preferences) operate on blocks of cells. You can select a block by using the Select tool, or by shift-clicking.

Edit->Cut
Copy and clear the selected region. Note: the copy buffer is preserved when you start or load a new file.
Edit->Copy
Copy the selected region.
Edit->Clear
Clear (but don't copy) the selected region.
Edit->Paste
Paste the contents of the copy buffer to the grid. If there is a currently selected region, it will be implicitly copied and used in place of the copy buffer. After you enter this command, a highlighted rectangle will appear as you move over the grid, so that you can choose where to paste. Left-click when the rectangle is in the right position.
Edit->Move
This is essentially a shortcut for Cut-Paste: it cuts the selected region, then allows you to choose a spot to paste it. But the original region is left on display while pasting, so that you can easily displace a block of cells by a chosen offset.
Edit->Cancel Paste
Cancel a pending Paste or Move operation.
Edit->Preferences
Pop up the LucidLife Preferences dialog.

6.4. Run Menu

Run->Playing
When this item is checked, the pattern will advance.
Run->Step
Run the pattern for one generation.
Run->Jump
Jump ahead to a particular generation as quickly as possible, without display updates.
Run->Faster
Increase the run speed (by a customizable increment).
Run->Slower
Decrease the run speed (by a customizable increment).

6.5. Help Menu

Help->Help
Display the LucidLife help file in a web browser window. You can change the choice of browser in Preferences/Help.
Help->Pattern Archive Notes
Display Alan Hensel's notes on the Pattern Archive in a browser window.
Help->GLF File Format
Display notes on LucidLife's native file format in a browser window.
Help->About LucidLife
Display version, author, license and cute mascot for LucidLife.


7. Configuring LucidLife

A Preferences dialog can be popped up via the Edit->Preferences menu item.

Colors
Four colors are used for the Life viewport: background, live cells, visual grid (only drawn at zoom levels >= 4:1), and selection box (when cutting and pasting). Click the color buttons to choose a new color.

Speed
The maximum speed may be adjusted to allow LucidLife to reach its full potential on faster machines. Note that although LucidLife will allow you to set a very high maximum speed, it will of course only really go as fast as you processor can handle.
The "Skip frames to achieve speed" checkbox allows you to choose whether LucidLife will skip the drawing of some frames in order to allow the game to advance as fast as possible.


8. Keybindings

Keybindings are displayed in the menus, but here's a list of the most useful and/or non-obvious ones. Note that NumLock must be on to use the numeric keypad.


Key Action
S Start/stop the pattern
T Step ahead one tick
J Jump to a generation
D View/edit pattern description
R Reopen the current file
F11 Toggle fullscreen mode
M Move a block of cells
C Choose pattern collection
P Edit preferences
Numeric keypad Scroll the viewport in 8 directions
Ctrl-Keypad Scroll by pages
Keypad-5 Recenter at the middle of the world
Ctrl-+ and Ctrl-- Zoom in and out, respectively
1, 2, 4, 8, Z Zoom 1:1, 2:1, 4:1, 8:1, and 16:1, respectively
, and . Slow down and speed up, respectively
Ctrl-1 through Ctrl-5 Load a recently accessed file (Ctrl-1 is most recent)