🚀 go-pugleaf

Clayten_Hamacher@mindlink.bc.ca (Clayten Hamacher) writes:

>I have been meaning to write a map generator, not just one that puts
>mountains and rivers on a map, but one that generates a world like we have.

>I'd use most of the rules of plate techtonics and a few other things, maybe a
>gravity variant (how many hills and how high..)

[tectonic "algorithm" deleted]

>Please send and/or post any ideas/suggestions etc.

Running a good tectonic simulation is hard. It is only moderately
difficult to move the plates, but deciding how the crust folds when
plates meet is extremely difficult. Also, one should consider erosion
as well. At present, our world is determined as much by erosion as by
tectonics. Old mountains become flat and glacial action has rounded
the mountains of Scandinavia. Rivers have carved canyons and
accumulated silt has created new land. Erosion from rapid temperature
changes has powdered rock to sand in the deserts. Etc. etc. etc.

Since erosion depends on climate, this should be simulated at the same
time.

All in all, trying to make a "realistic" world development simulation
is going to be extremely difficult and time consuming.

I have made a program that uses a variant of the mid-point
displacement method to create a fractal landscape on a spherical
planet. It is simple, relatively fast, and makes some fairly pleasing
and superficially natural looking planets, but on closer inspection it
is obvious that it is not natural: mountains come in clumps rather
than chains, there are no rivers and the lakes all have their surface
at sea level. I have added (not on the sphere, but on a flat map) rain
and flow of water to generate high-altitude lakes and rivers, but it
is very time consuming and not (yet) capable of making good-looking
rivers.

Anyway, if you have a magical world, why assume that it is created
like our own? Glorantha is an example of the opposite and I'm
currently working on Yggdrasil, the world tree. People live on the
branches, where the folds in the bark form mountains and seas. The
width of the largest branches is about the width of Western Europe
(from Britain and Spain in the west to Germany and Italy in the east).

Other example from literature are Diskworld and Ringworld. Though the
latter is not constructed magically, a similar concept could be used.

	Torben Mogensen (torbenn@diku.dk)

There was one of these in the USML (Universal Simulation Mailing List)
archive, which apparently no longer exists.  I have a copy of the program,
which was called plates.c, but I have hacked on the copy I have, so I'd
rather not distribute it.  Problems I had with the program were
	1) The initial plates were polygonal (the voronoi polygons of
	a random point set), which did not look good.
	2) If I ran the simulator long enough to grind off the vertices,
	I got oceans full of so many little isands that ocean crossings
	would be trivial.
	3) Erosion was just wrong. I got one mountain that was 2 or 3 
	times the height of Everest.  Also, eroded material didn't really
	go anywhere.

Here is the comment from the beginning of the program:

/*
 * A program to simulate tectonics.
 *
 * Copyright 1988 by Mark Isaak.
 * You may distribute this however you like, as long as you don't sell it
 * and you keep this notice in it.
 *
 * Wish list:
 *      Do it on a sphere, not a square torus
 *      Give plates angular momentum
 *      Make some constants variable
 *      Horsts and grabens
 *      Let 2 plates fuse together and/or 1 plate split apart sometimes
 *      Astroblemes
 *      Take density of rock into account
 */

In article <19376@mindlink.bc.ca> Clayten_Hamacher@mindlink.bc.ca (Clayten Hamacher) writes:
>I have been meaning to write a map generator, not just one that puts
>mountains and rivers on a map, but one that generates a world like we have.
>
>I'd use most of the rules of plate techtonics and a few other things, maybe a
>gravity variant (how many hills and how high..)
>
>Start with a sphere, draw 'plates' on it.
>Toss a big chunk of land (1/3 or so) in one clump onto the map.
>Assign directions and speeds to the 'plates', making all move roughly out
>from        the center.
>Keep track of convection currents for future use.
>Note what plates eventually meet, depending on the type of boundary they'd
>       form different landscape features (volcanoes etc)
>Add hotspots and other 'phenomenon' to make small deformities.
>Map the land roughly, only the big rivers and such things.
>Print map of random Earthlike world..
>
>Sorta simplified but I think it'd work.
>
>Things like land percentage, world size, gravity (or link it directly to
>size), number of 'phenomenon', tiny plates, hot spots, etc..(sorta like
>turning disasters on in Sim City...:) )
>
>Then output the map in a graphic (human form) and a computer readable map as
>well (for a later program to map any specific part in great detail).
>
>Please send and/or post any ideas/suggestions etc.
>
>--
>
>Clayten_Hamacher@Mindlink.bc.ca                 Land of the rising snow.

Look at SimEarth for an example.  Also there is an archive site for this 
kind of stuff ... you may want to check out the rec.games.frp.archives FAQ
for the location.  I remember plate tectonic code and several other goodies 
that could be adapted.




-- 
Bert Medley                            | HOUNIX:  bmedley@hounix.org
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