Скачать CPlasma v1.0 -- Polar Based Plasma

31.03.1995
Скачать файл (15,17 Кб)

Intro
-----
    A couple of years ago, when the plasma algorithms first started
showing up, I noticed that the plasma was based upon a rectangle.
Take a good look close up on a smooth plasma, and you can see all
sorts of edges in the colors.  This is because most plasma algorithms
uses cartesian coordinates, an (x,y) way of determaining position.
This is done because monitors use cartesian coordinates.
It's easiest.
    But I wondered: what about circle based plasma?  Would it look the
same?  This program is the result.
    I think it looks like some sort of explosion.  That's why I added
the palette rotations--to see what it would look like "animated."
    Instead of creating points from (x1,y1) and (x2, y2), I create
points from (Angle1, Radius1) to (Angle2, Radius2).  However, it
really uses the same _essential_ technique as the regular plasma.
I just use an angle and radius.  For each radius R that I figure
outwards, I do the following:
  1)  To figure out angle 2, which is between angle 1 and angle 3,
      I take the average of the pixel at angle 1 and angle 3.
  2)  I add/subtract an amount of randomness. The amount of randomness
      that is added/subtracted is based upon the chord length between
      the two pixels. Note that it is the chord length, not a simple
      distance formula.
  3)  Then, I figure out the pixel between angle 1 and angle 2, as well
      as the pixel between angle 2 and angle 3.  I do this, of course,
      recursively.

----------
Running It
----------
    When the program is first run, there's several questions that
must be first answered.  The defaults run fine, but here's what each
of them do....

RandSeed
    If you enter a number here, and you like the result,
you can enter the same number here and get the exact same result.

Roughness
    This number determines how rough the plasma is.  The higher the
number, the rougher the plasma.

Radii
    This is the radius, in pixels.  The maximum radius is 100 pixels.

Fadeout
    Fadeout controls how much the plasma darkens as it gets near the
edges of the radius.

Ejection
    The ejection angle is the minimum angle that the plasma will
compute. For large plasmas, you'll want a very small value. For small
plasmas, you can have a large ejection value without any trouble.
If the ejection value is too high, you'll have spots in your plasma
which are not figured out. It'll look kind of weird. If the ejection
value is too small, it won't affect the plasma any. However, it will
increase the time the program takes to generate the plasma.

Palette Delay
    This will speed up/slow down the rate at which the palette
rotates.  The higher the delay, the slower it goes.

Screen Aspect
    The VGA mode 13hex is not particularly well suited for circles.
The pixels aren't squares, so circles look like elipses. If you answer
"Y"es to this question, the plasma will be distorted to look circular.

Random Endpoints
    If you don't want this, then the endpoints of the axis of the
plasma will be black.  It'll have the effect of slightly darkening and
distorting the plasma.  The center will be white with this turned off.
With this on, the endpoints are set at random.

Random Center
    If you selected that you want random endpoints, you'll also get
to choose whether or not to have a random center.

    Then, the plasma will be drawn.  After it is done, you'll here a
beep.  Just press a key.
    The screen will become blue for about a second.  You'll be able to
see if your ejection value was too small.  If it was, you'll see bits
of blue showing from behind the plasma.
    Then, the screen will go dark, and the palette will rotate
through and fade out.  Press any key to do it again.  Press the 
or the 'Q' key in order to quit to the next palette rotation.
    To stop any of these palette rotations, just hit any key.

----------
In Closing
----------
    That's all of the program.  The source code is included.  It does
exactly what the EXE does.
    Go ahead, distribute this.  It's not exactly optimized, or even
well written.  But it works, and I've yet to see a program that does
this, so I'm releasing it to everyone.  You can use parts of the code
in your code. However, you may not modify the source code, then
redistribute it.
You must include this file, the original executable, and the original
source code when distributing this program.  You can't charge money
for this program.  This program is presented "as is" and with all
defects.  The programmer may not be held liable for damage to data,
property, and various inhabited planets due to this program.