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 CPlasma v1.0 -- Polar Based Plasma   Jason Trowbridge 31.03.1995

Эффект Плазмы, использующий полярные координаты вместо декартовых.
A really cool plasma thing with lots of options.



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CPlasma v1.0 -- Polar Based Plasma By Jason Trowbridge ----- 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 <ESC> 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. Contact me if you like it! jrsx03b@prodigy.com trowbri@unm.edu <- Soon to change....