Selecting Turtles
There can only be one turtle selected at any time.
There can also be no selected turtle. To select a
turtle, you click on the turtle's drawing with the
left mouse button. When a turtle is selected, it
shows a second black board around the original blue
or red border. To select no turtles, left-click the
mouse anywhere in the window where these is no turtle.
Turtles And The Clipboard
You may copy and paste turtles to and from the
clipboard just like any other Windows program.
When a turtle is copied to the clipboard, using
the Copy command in the Edit menu, both textual
and graphical data are placed on the clipboard.
This means that you can edit the program of the
turtle, which is placed on the clipboard as text
data. It also means that you can paste the picture
that the turtle draws into any graphics program,
such as PhotoShop or Illustrator.
The textual data will contain the logo algorithm
used by the turtle to draw its figure. This data
can then be pasted into any text editor, or other
application that utilizes text. Further, this
textual data may be pasted back into any selected
turtle to replace its algorithm (and thus its figure)
with that represented by the algorithm on the clipboard.
To try this, select a turtle, select Copy, select a
different turtle, finally, select Paste.
The graphical data contains the Windows standard
MetaFile data that draws the turtle's image. This
MetaFile data can be pasted into any application
that accepts MetaFile data. This allows you to paste
a turtle's figure into any windows graphics application.
Technically, the format of the data is the Windows
Enhanced MetaFile.
Zooming In On A Turtle's Figure
To display a turtle's figure in the full area of the
population window (to blow it up), simply right-click
on the turtle's figure.
This will cause the turtle to display its figure full
size in the contents of the population window. To
return to viewing the entire population, left-click
anywhere within the contents of the window, and the
entire population will be displayed once again.
Doping Turtles
Doping a turtle means to replace its algorithm with
another. This causes the turtle to display a figure
that you select. This can be accomplished with the
algorithm from a previously saved turtle, or it could
be an algorithm that you have copied and modified, or
it could be an algorithm that you have manufactured
yourself using the Logo language.
Doping a turtle from a previously saved turtle is
accomplished via the Load Turtle command in the File
menu. This command is only highlighted when a turtle
is selected. When you select the command, the Open
File Dialog will be displayed asking you to select
a file, which contains a previously saved turtle.
Once you select a file, this file's turtle algorithm
will replace the algorithm of the selected turtle,
and the new figure will be drawn in the selected
turtle's square.
Doping a turtle from an algorithm in textual form
is accomplished via the Paste command in the Edit
menu. When the Paste command is selected, it will
look on the Clipboard for textual data. If textual
data is found, it is assumed to be an expression
using the logo language. If this turns out to be
true, and the algorithm is syntactically correct
(meaning there are no mistakes in the expression),
then the currently selected turtle will have its
algorithm replaced with the algorithm from the
clipboard and a new figure will be drawn for the
turtle. If the algorithm is not valid, then the
application will display an error message, and
leave the selected turtle unmodified.
Mutating Turtles
Mutating turtles involves randomly generating a logo
expression and then randomly splicing this expression
into the algorithm of the turtle. This can have a wide
range of effects, from no visual difference, to
profound visual change including no display at all.
Mutating a turtle is accomplished by selecting the
turtle's figure then selecting the Mutate Turtle item
in the File menu. This will cause the mutation to be
made to the selected turtle, and its new figure to be
displayed in its square.
Mutation is usually used when a population appears to
be stuck in a particular feature set and it is proving
difficult to move the population into any new directions
without the injection of some random figures.
Note that sometimes when you mutate a turtle, the figure
that it draws will not change. This is normal. It means
that the mutation occurred in a part of the program that
does not display, or in a portion where the modifications
are not significant. Some turtles will never change what
they draw without many mutations. Others will suddenly
drawing nothing.
Printing Turtles
You may print a turtle's figure to any Windows supported
printer. To print a turtle select the desired turtle's
figure, then select the Print Turtle command from the
File menu.
You can select Landscape mode for turtles whose drawings are wide.
When you print a turtle, you will first be presented with a
dialog box asking you for the pen width. This is the width
of the pen that will draw the turtle's figure. After you
print several turtles, you will begin to note some significant
differences with what you see on the screen. One of the primary
differences will be the pen width. Lines on the screen are
always printed with a width of 1. However, some turtles, when
printed with a pen width of 1, do not look very good. Other
turtles, because of their many overlapping lines, will look
bad is the pen width is too thick.
For this reason, you are asked to specify the pen width you
wish to use to print the turtle. A width of zero tells the
printer to use the thinnest lines it is capable of printing.
Larger widths cause thicker lines to be printed. On my HP
DeskJet printer, I typically use widths between 0 and 4.
Please note that what you see on a printer can seem completely
different than what you saw on the screen. There are many
reasons for this. The biggest reason is simply that line
widths will vary, total number of pixels for drawing increases
dramatically on the printer, and because colors on the monitor
do not always match the printed colors well.
Saving Turtles
You may save turtles to a file. Currently, only the text
of the turtle's Logo program is saved. You can edit this
text, and thus the turtle's algorithm, and load the turtle
once again. This allows you to modify turtles as you see fit.
You save a turtle by selecting the turtle (using a left-click),
then selecting the Save Turtle command from the File menu.
This will display a Save As Dialog box. Enter the name of
the file you want to save the turtle in, and click the Save
button. The filename will have the extension ".txt" added
to it, unless you put the suffix on yourself. You load saved
turtles using the Doping technique. You select a turtle to
replace and use the Load Turtle command from the File menu.
Select the file you saved the turtle in and it will replace
the one selected.
You can also save and load populations. This saves all of
the turtles in a population into a single file. Populations
can be saved to a file using the Save Population command
in the File menu. Populations can be loaded again into a
population window using the Load Population command in the
File menu. When you load a saved population, only the number
of turtles in the window you are loading into will be loaded.
In other words, if a saved population file has 100 turtles
in it, and you load it into a population window that is
displaying 50 turtles, only the first 50 turtles will be
loaded from the file.