Hello all,
-----Original Message-----
FOTD -- December 18, 2003 (Rating 5)
Fractal visionaries and enthusiasts:
<SNIP>
The bubbly effect in the image was achieved by rendering the scene with the outside=fmod and the proximity=3. At the moment I am not sure how the 'fmod' option works and how the proximity affects it, but the information is somewhere in the monumental stack of help included with the Fractint program.
As author of the "fmod" functionality, I feel it is my duty to explain this feature! The following explanation was provided by me in response to Jim's FOTD "FMOD Fantasy" of the 4th of November 2002. Seeing as it has been over a year since then, I thought it wouldn't be a problem to state it again... "fmod" tests the value of the iterate Z at each iteration. If the magnitude of the Z is less than 'proximity', the point is (provisionally) coloured using colour [0...255] according to the position of |Z| in the line segment [0...proximity] i.e |Z|=0.5*proximity will be coloured 128 (or thereabouts). On each iteration, if |Z|<proximity then the point is recoloured even if |Z| is now bigger than it was on a previous iteration. This goes on until 'maxiter' is reached and the last provisional point colour is then commited to the image. The resulting pattern is typically overlapping (and squashed) circles. The overlap is due to allowing subsequent iterations to set the colour even if they have a bigger |Z| than previous iterations. The general 'contour' pattern occurs as the contours are centered on values of 'c' that cause |Z| to tend towards the origin (0+0i) as they are iterated. values of 'c' that lead |Z| inexorably to the origin (lets denote one 'X') will be at the centre of fmod patterns, and values of 'c' nearby 'X' will cause |Z| to whirl around the origin in orbits of increasing radius as point 'c' moves away from 'X'. This is a bit tricky to explain, but Fractint's "orbit" feature will show it very nicely! Best regards, Iain Stirling. --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.551 / Virus Database: 343 - Release Date: 11/12/2003