Plasma effect
Encyclopedia
The plasma effect is a computer-based visual effect animated in real-time. It uses cycles of changing colours warped in various ways to give an illusion of liquid, organic movement.
Plasma was probably invented by demo coders
for use in their demos
where the effect was heavily used, especially in the early 1990s. The effect was particularly common on the Commodore Amiga where it could be implemented very efficiently by using the features of the proprietary display hardware. Plasma can also be implemented easily in software rendering by using sinus tables and pseudocolor palettes
, and it has also been the first true demo effect for many beginning PC democoders.
The fractal software Fractint
also incorporates an algorithm known as "plasma", which, when combined with the color cycling feature of the software, can provide a result which resembles a typical plasma effect used in demos. The technical basis, however, is completely different, and a color cycling plasma is somewhat less dynamic than a demo plasma.
As there are many "hacked" approaches for implementing a plasma effect, this outline of an algorithm will just describe the theoretical basis for the effect. In order to achieve a sufficiently fast and good looking real time implementation (especially on the limited hardware available at the time this effect was at the height of its popularity in the 1990s), one would often do "non-correct" approximations to this algorithm. This, however, can often be done without noticeable visual differences.
This algorithm is given in two dimensions, but could easily be adopted to any number of dimensions for any number of color channels.
Let
be a multi-frequency noise function of two 2 variables (e.g., a perlin noise
function). Let each color component
at the pixel 
be a linear function of the expression 
.
is a fractal that the plasma effect can be applied to with nice results.
Demoscene
The demoscene is a computer art subculture that specializes in producing demos, which are non-interactive audio-visual presentations that run in real-time on a computer...
for use in their demos
Demo (computer programming)
A demo is a non-interactive multimedia presentation made within the computer subculture known as the demoscene. Demogroups create demos to demonstrate their abilities in programming, music, drawing, and 3D modeling...
where the effect was heavily used, especially in the early 1990s. The effect was particularly common on the Commodore Amiga where it could be implemented very efficiently by using the features of the proprietary display hardware. Plasma can also be implemented easily in software rendering by using sinus tables and pseudocolor palettes
Palette (computing)
In computer graphics, a palette is either a given, finite set of colors for the management of digital images , or a small on-screen graphical element for choosing from a limited set of choices, not necessarily colors .Depending on the context In computer graphics, a palette is either a given,...
, and it has also been the first true demo effect for many beginning PC democoders.
The fractal software Fractint
Fractint
FractInt is a freeware program that can render and display many kinds of fractals.-Name:Its name comes from the words fractal and integer, since the first versions of it computed fractals by using only integer arithmetic , which led to much faster rendering on x86 computers without math coprocessors...
also incorporates an algorithm known as "plasma", which, when combined with the color cycling feature of the software, can provide a result which resembles a typical plasma effect used in demos. The technical basis, however, is completely different, and a color cycling plasma is somewhat less dynamic than a demo plasma.
Synopsis
This algorithm is given in two dimensions, but could easily be adopted to any number of dimensions for any number of color channels.
Let
be a multi-frequency noise function of two 2 variables (e.g., a perlin noisePerlin noise
Perlin noise is a computer-generated visual effect developed by Ken Perlin, who won an Academy Award for its use in the motion picture Tron...
function). Let each color component
at the pixel be a linear function of the expression .See also
Plasma fractalDiamond-square algorithm
The diamond-square algorithm is a method for generating highly realistic heightmaps for computer graphics. It is a slightly better algorithm than the three-dimensional implementation of the midpoint displacement algorithm which produces two-dimensional landscapes...
is a fractal that the plasma effect can be applied to with nice results.