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1990-07-16
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Mountain Fractals
Version 1.1
Instructions
This is a small program that generates three-dimensional mountain
fractals. These fractals can then be saved on disk as CAD-3D 1.0
objects, and loaded into that program for further manipulation.
To use this program, run FRACTALS.PRG from any resolution. The
initial alert box will provide you with two choices, Begin or
Quit. Selecting Begin allows you to generate a fractal, and
selecting Quit exits the program.
After selecting Begin, you must select the depth of the fractal.
The depth is the amount of detail to be included; it would also
take more time, but since the time is so short (the most detailed
fractals take about 5 seconds) that doesn't really amount to
much. Level 5 is the least detailed fractal; these objects have
only 256 faces and 153 points. Level 7 is the most detailed;
these objects have 4,096 faces and 2,145 points.
To select the fractal depth, click on the left and right arrow
buttons in the alert box to change the value in the center box.
When you are happy with the value selected, click on the center
box.
After choosing the fractal depth, you must choose the rockiness
for the fractal. Lower values here make rockier fractals; a
value of 3 (the lowest allowed) creates very chaotic fractals. A
value of 8, however, creates fractals that are very smooth (not
flat, smooth). Select the rockiness in the same manner as you
selected the depth.
Now you are given a last chance to bail out. An alert box will
appear, telling what depth and rockiness you have selected, and
presenting you with the options of Proceed and Cancel. Selecting
Proceed will generate the fractal; selecting Cancel will abort
the operation and return you to the initial alert box.
Once the fractal has been generated, it will be drawn on the
screen in a manner similar to CAD's "hidden" mode. The drawing
will automatically be scaled to fit on the screen; since it is
only two colors, however (white on black) I would suggest running
this program in the highest resolution possible. After looking
at the fractal for as long as you like, click the mouse button
and select the .3D file to write the object to. You will need
CAD 3D to look at these objects. Selecting Cancel will abort the
save. After saving the fractal (or not), you will be returned to
the initial alert box.
Load the fractal objects into CAD as you would any other object.
For some reason the lighting information and shading of the
object are not saved properly; reshade the object ("Mountain") to
a brightness of 7, and switch light source A to intensity 7.
Move the camera to approximately +70 degrees vertically and 180
degrees horizontally, select 14 shades, and view the object in
Solid mode. Voila!
This was the first program I wrote that generated CAD 3D objects.
Although not perfect, it does work for the most part. Future
programs dealing with CAD will be a function plotter and a
Mandelbrot Set generator (3D Mandelbrot sets!)
Some of the other (non-CAD-related) programs I have written are
DOUBLER, the program that turns single-sided disks into double-
sided disks, without erasing the data, and PURGER, a program that
erases an entire disk in less than five seconds.
-Damien Jones
Fixed from version 1.1: A minor bug in the fractal display only drew
half of the triangles that make up the fractal. It has been fixed.
Also a bug in the fractal generation (dealing with the edges of the
fractal) was fixed.