FireLink

The fire effect is one of the most iconic demoscene tricks — every demo on the Amiga, Atari ST or PC had one. The algorithm is beautifully simple: seed random hot pixels at the bottom of the screen, then propagate upward by averaging each pixel with its neighbors below and subtracting a small cooling factor. The result is a surprisingly realistic flame that rises, flickers and fades — all from a few lines of integer math and a color palette lookup.

FireLink wraps this classic effect into a clickable banner applet. A transparent foreground image (the link text or logo) floats over the flames, with an optional second image for mouseover state. The three-color gradient (backColor → midColor → endColor) lets you create anything from traditional red/yellow fire to white smoke, green plasma or blue ice. The cool parameter controls flame height, and with mouse enabled you can paint fire with the cursor.

Features

Real-time fire simulation with neighbor-averaging diffusion
Transparent foreground image overlay (GIF)
Mouseover image swap
Fully customizable three-color gradient
Adjustable flame height, spot density and clearing rate
Mouse-as-torch interaction
Clickable link with target window control

Parameters

Name	Type	Description	Default	Required
`image`	filename	Transparent foreground image (GIF) shown over the fire	–	no
`image2`	filename	Alternative image shown on mouseover	–	no
`cool`	int (1–16)	Cooling factor — higher values produce shorter flames	1	no
`spots`	int	Number of new fire hotspots seeded at the bottom each frame	width/16	no
`clears`	int	Number of bottom pixels cleared each frame	width/8	no
`mouse`	–	Enable mouse-as-torch (presence enables it)	off	no
`backColor`	hex color	Color gradient start (coldest)	#000000	no
`midColor`	hex color	Color gradient midpoint	#FF0000	no
`endColor`	hex color	Color gradient end (hottest)	#00FFFF	no
`link`	URL	Link target when applet is clicked	–	no
`targetWindow`	String	Target window for link (`_blank`, `_self`, etc.)	_self	no

Code Example

<applet archive="FireLink.jar"
  code="FireLink.class" width="100" height="30">
  <param name="link" value="https://www.chriscohnen.de">
  <param name="image" value="hotlink.gif">
  <param name="cool" value="2">
  <param name="spots" value="20">
  <param name="clears" value="10">
  <param name="backColor" value="#000000">
  <param name="midColor" value="#FF0000">
  <param name="endColor" value="#FFFF66">
</applet>

Version History

Version	Date	Changes
2.1	May 1997	First public version — link image with background fire
3.0	November 1999	Mouseover image, target window, renamed “pic” to “image”
3.2	November 2003	Build system, obfuscation
3.3	August 2004	Fixed left mouse click to link