sgt-blackbox - Ball-finding puzzle
sgt-blackbox [--generate n] [--print wxh [--with-solutions] [--scale n] [--colour]] [game-parameters|game-ID|random-seed]
A number of balls are hidden in a rectangular arena. You have to deduce the positions of the balls by firing lasers positioned at the edges of the arena and observing how their beams are deflected.
Beams will travel straight from their origin until they hit the opposite side of the arena (at which point they emerge), unless affected by balls in one of the following ways:
Beams that are reflected appear as a ‘R’; beams that hit balls head-on appear as ‘H’. Otherwise, a number appears at the firing point and the location where the beam emerges (this number is unique to that shot).
You can place guesses as to the location of the balls, based on the entry and exit patterns of the beams; once you have placed enough balls a button appears enabling you to have your guesses checked.
Here is a diagram showing how the positions of balls can create each of the beam behaviours shown above:
1RHR---- |..O.O...| 2........3 |........| |........| 3........| |......O.| H........| |.....O..| 12-RR---
As shown, it is possible for a beam to receive multiple reflections before re-emerging (see turn 3). Similarly, a beam may be reflected (possibly more than once) before receiving a hit (the ‘H’ on the left side of the example).
Note that any layout with more than 4 balls may have a non-unique solution. The following diagram illustrates this; if you know the board contains 5 balls, it is impossible to determine where the fifth ball is (possible positions marked with an x):
-------- |........| |........| |..O..O..| |...xx...| |...xx...| |..O..O..| |........| |........| --------
For this reason, when you have your guesses checked, the game will check that your solution produces the same results as the computer's, rather than that your solution is identical to the computer's. So in the above example, you could put the fifth ball at any of the locations marked with an x, and you would still win.
Black Box was contributed to this collection by James Harvey.
To fire a laser beam, left-click in a square around the edge of the arena. The results will be displayed immediately. Clicking or holding the left button on one of these squares will highlight the current go (or a previous go) to confirm the exit point for that laser, if applicable.
To guess the location of a ball, left-click within the arena and a black circle will appear marking the guess; click again to remove the guessed ball.
Locations in the arena may be locked against modification by right-clicking; whole rows and columns may be similarly locked by right-clicking in the laser square above/below that column, or to the left/right of that row.
The cursor keys may also be used to move around the grid. Pressing the Enter key will fire a laser or add a new ball-location guess, and pressing Space will lock a cell, row, or column.
When an appropriate number of balls have been guessed, a button will appear at the top-left corner of the grid; clicking that (with mouse or cursor) will check your guesses.
If you click the ‘check’ button and your guesses are not correct, the game will show you the minimum information necessary to demonstrate this to you, so you can try again. If your ball positions are not consistent with the beam paths you already know about, one beam path will be circled to indicate that it proves you wrong. If your positions match all the existing beam paths but are still wrong, one new beam path will be revealed (written in red) which is not consistent with your current guesses.
If you decide to give up completely, you can select Solve to reveal the actual ball positions. At this point, correctly-placed balls will be displayed as filled black circles, incorrectly-placed balls as filled black circles with red crosses, and missing balls as filled red circles. In addition, a red circle marks any laser you had already fired which is not consistent with your ball layout (just as when you press the ‘check’ button), and red text marks any laser you could have fired in order to distinguish your ball layout from the correct one.
(All the actions described below are also available.)
These parameters are available from the ‘Custom...’ option on the ‘Type’ menu.
These actions are all available from the ‘Game’ menu and via keyboard shortcuts, in addition to any game-specific actions.
(On Mac OS X, to conform with local user interface standards, these actions are situated on the ‘File’ and ‘Edit’ menus instead.)
The Load and Save operations preserve your entire game history (so you can save, reload, and still Undo and Redo things you had done before saving).
Some games (such as Solo) are capable of solving a game ID you have typed in from elsewhere. Other games (such as Rectangles) cannot solve a game ID they didn't invent themself, but when they did invent the game ID they know what the solution is already. Still other games (Pattern) can solve some external game IDs, but only if they aren't too difficult.
The ‘Solve’ command adds the solved state to the end of the undo chain for the puzzle. In other words, if you want to go back to solving it yourself after seeing the answer, you can just press Undo.
There are two ways to save a game specification out of a puzzle and recreate it later, or recreate it in somebody else's copy of the same puzzle.
The ‘Specific’ and ‘Random Seed’ options from the ‘Game’ menu (or the ‘File’ menu, on Mac OS X) each show a piece of text (a ‘game ID’) which is sufficient to reconstruct precisely the same game at a later date.
You can enter either of these pieces of text back into the program (via the same ‘Specific’ or ‘Random Seed’ menu options) at a later point, and it will recreate the same game. You can also use either one as a command line argument (on Windows or Unix); see below for more detail.
The difference between the two forms is that a descriptive game ID is a literal description of the initial state of the game, whereas a random seed is just a piece of arbitrary text which was provided as input to the random number generator used to create the puzzle. This means that:
(Use the ‘About’ menu option to find out the version number of the program. Programs with the same version number running on different platforms should still be random-seed compatible.)
A descriptive game ID starts with a piece of text which encodes the parameters of the current game (such as grid size). Then there is a colon, and after that is the description of the game's initial state. A random seed starts with a similar string of parameters, but then it contains a hash sign followed by arbitrary data.
If you enter a descriptive game ID, the program will not be able to show you the random seed which generated it, since it wasn't generated from a random seed. If you enter a random seed, however, the program will be able to show you the descriptive game ID derived from that random seed.
Note that the game parameter strings are not always identical between the two forms. For some games, there will be parameter data provided with the random seed which is not included in the descriptive game ID. This is because that parameter information is only relevant when generating puzzle grids, and is not important when playing them. Thus, for example, the difficulty level in Solo (sgt-solo(6)) is not mentioned in the descriptive game ID.
These additional parameters are also not set permanently if you type in a game ID. For example, suppose you have Solo set to ‘Advanced’ difficulty level, and then a friend wants your help with a ‘Trivial’ puzzle; so the friend reads out a random seed specifying ‘Trivial’ difficulty, and you type it in. The program will generate you the same ‘Trivial’ grid which your friend was having trouble with, but once you have finished playing it, when you ask for a new game it will automatically go back to the ‘Advanced’ difficulty which it was previously set on.
The ‘Type’ menu, if present, may contain a list of preset game settings. Selecting one of these will start a new random game with the parameters specified.
The ‘Type’ menu may also contain a ‘Custom’ option which allows you to fine-tune game parameters. The parameters available are specific to each game and are described in the following sections.
(This section does not apply to the Mac OS X version.)
The games in this collection deliberately do not ever save information on to the computer they run on: they have no high score tables and no saved preferences. (This is because I expect at least some people to play them at work, and those people will probably appreciate leaving as little evidence as possible!)
However, if you do want to arrange for one of these games to default to a particular set of parameters, you can specify them on the command line.
The easiest way to do this is to set up the parameters you want using the ‘Type’ menu (see above), and then to select ‘Random Seed’ from the ‘Game’ or ‘File’ menu (see above). The text in the ‘Game ID’ box will be composed of two parts, separated by a hash. The first of these parts represents the game parameters (the size of the playing area, for example, and anything else you set using the ‘Type’ menu).
If you run the game with just that parameter text on the command line, it will start up with the settings you specified.
For example: if you run Cube (see sgt-cube(6)), select ‘Octahedron’ from the ‘Type’ menu, and then go to the game ID selection, you will see a string of the form ‘o2x2#338686542711620’. Take only the part before the hash (‘o2x2’), and start Cube with that text on the command line: ‘sgt-cube o2x2’.
If you copy the entire game ID on to the command line, the game will start up in the specific game that was described. This is occasionally a more convenient way to start a particular game ID than by pasting it into the game ID selection box.
(You could also retrieve the encoded game parameters using the ‘Specific’ menu option instead of ‘Random Seed’, but if you do then some options, such as the difficulty level in Solo, will be missing. See above for more details on this.)
(This section only applies to the Unix port.)
In addition to being able to specify game parameters on the command line (see above), there are various other options:
If game parameters are specified on the command-line, they will be used to generate the game IDs; otherwise a default set of parameters will be used.
The most common use of this option is in conjunction with --print, in which case its behaviour is slightly different; see below.
On each page of puzzles, there will be w across and h down. If there are more puzzles than w×h, more than one page will be printed.
If --generate has also been specified, the invented game IDs will be used to generate the printed output. Otherwise, a list of game IDs is expected on standard input (which can be descriptive or random seeds; see above), in the same format produced by --generate.
For example:
sgt-net --generate 12 --print 2x3 7x7w | lpr
will generate two pages of printed Net puzzles (each of which will have a 7×7 wrapping grid), and pipe the output to the lpr command, which on many systems will send them to an actual printer.
There are various other options which affect printing; see below.
If --generate has also been specified, the invented game IDs will be used to generate the printed output. Otherwise, a list of game IDs is expected on standard input (which can be descriptive or random seeds; see above), in the same format produced by --generate.
For example:
sgt-net --generate 12 --save game --save-suffix .sav
will generate twelve Net saved-game files with the names game0.sav to game11.sav.
The following options are only meaningful if --print is also specified:
Full documentation in /usr/share/doc/sgt-puzzles/puzzles.txt.gz.