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CD ROM Paradise Collection 4
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CD ROM Paradise Collection 4 1995 Nov.iso
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cdrift3.zip
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PARAMS.DOC
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1990-02-22
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If you give tec a filename as a command line argument, it will read
parameters from that file. If you hand it '-' as an argument, it will
read them from stdin. For example, you could type "tec - < foo", or
"tec foo". The '-' option is handy for pipes.
The parameter file is optional; all of the parameters you can change
have defaults. Thus, the parameter file need contain only the parameters
you want to change. A parameter file looks like LISP; for example,
to change the XSIZE parameter, the file would have the one line
(XSIZE 40)
Parameters can also be vectors; for example
(MOVERATE (1 1 1))
The parameters are either easy or hard. This rating concerns how much
you have to know about the simulation to change the parameters. Easy
ones just affect run time, resolution, and so on. Hard ones should
only be changed if you understand the code pretty well.
Easy parameters:
DRAWMODE - 0 produces no output, 1 produces a long text file (default),
2 produces a summary text file and 3 produces PostScript
grayscale drawings.
DRAWEVERY - How many steps should be iterated for each output. Default 1,
but this produces an awful lot of text. Reasonable values
for non-interactive runs are 5 or 10. Supercontinents appear
every 25 steps or so.
MAXSTEP - How many steps to run before terminating. Default 100.
XSIZE - Horizontal size of arrays. Default 90. To produce summaries
that fit on a normal page, I used 72.
YSIZE - Vertical size of arrays. Default 90. To produce the summaries
included in tec.out.[1-3], I used 48.
BLOBLEVEL - Indirectly related to size of initial supercontinent. I made
some 4000 blobs with different values of BLOBLEVEL to come up
with this empirical relationship: the average diameter of the
supercontinent is 83 - (0.625 * BLOBLEVEL). The blob is
clipped to the size of the world and can not exceed a
diameter of 64 anyway.
So to produce a text file with 10 pictures, you could use
(DRAWMODE 2) (DRAWEVERY 10) (XSIZE 72) (YSIZE 48) (BLOBLEVEL 80)
To produce a 20-page PostScript output with a little more detail, use
(DRAWMODE 3) (DRAWEVERY 5)
Hard Parameters:
ZINIT - Initial altitude of supercontinent. Default 22.
ZSUBSUME - Altitude added to leading edge of drifting plate. Default 16.
ZCOAST - Sea level. Everything below this is under water. Default 16.
ZSHELF - Minimum altitude for continental shelf. Default 8.
ZMOUNTAIN - Used in DRAWMODE 2; altitude above which a square is counted
as mountain instead of land. Default 48.
MAXBUMP - If two plates overlap on more than this number of squares,
the plates must be merged together. Default 50.
BUMPTOL - If the relative velocity of two touching plates is less than this
value, the plates will be merged together. Default 50.
MOVERATE - A vector of real numbers describing the rate at which plates
move apart, slow down, and then drift back together. Each
plate has an age, measured in steps from its creation. The age
is used as an offset into the vector. The result is a real
between -1.0 and +1.0 which is multiplied by the plate's original
movement vector. The default vector is
(1.0 1.0 1.0 0.7 0.4 0.1 -0.2 -0.5 -0.8 -1.0)
It can be interpreted this way. The first three steps a plate is
in motion, it moves at its normal velocity. During the 4-6
steps, it slows down. During the 7-10 steps, it moves the
opposite way from the way it started, at increasing speeds.
Thereafter, it keeps moving at its final velocity.
RIFTPCT - Percent chance that a rift will occur in a given step. Default 40.
MAXCTRTRY - The number of tries the rift routine will make to find an
acceptable place to start a rift. Default 50.
RIFTDIST - The minimum allowable distance between a proposed rift center
and the nearest coast. Default 5.
DOERODE - Whether or not to compute erosion. Default 1; if 0, the program
will run about twice as fast but will generate way too many
mountains, since the only thing that gets rid of mountains
is erosion.
ERODERND - The rounding factor used in erosion. Default 4. As this
parameter goes from 0 to 7, erosion occurs faster.
BENDEVERY - Each time a rift grows by this many squares, it is allowed to
bend a little bit. Default 6.
BENDBY - When a rift bends, it bends by a random angle in the range
-BENDBY ... +BENDBY multiplied by pi/2000. Default value is 100.
If BENDBY is too high or BENDEVERY is too low, very curvy rifts
will be generated, with unrealistic results.
SPPEDBASE - The minimum speed at which new plates will travel. Default 200.
SPEEDRNG - The actual speed at which a plate travels is SPEEDBASE +
rnd (SPEEDRNG). Default value is 300.