OK, this is weird...
This macro seems to exhibit a strange bug: when the random number seed is set to 1322
or 1342 (as far as I've discovered) the 3rd segment of the "worm" gets misaligned. The
misalignment grows with the total number of segments. I can't find any errors in my
code...
Could sb. try it out and tell me if I'm just being stupid or is this a genuine bug?

Thanx
Margus

//BEGIN SCENE

camera {orthographic
        location <0,10,2>
        up 10*.75*y
        right 10*x
        look_at z*2}
        
light_source {<20,60,-10> color 1}
#include "colors.inc"

//Generates random "Worm"
//LenStart      length of first segment
//LenEnd        length of last segment
//NumSegm       number of segments
//ExpL          segment length falloff (1-linear; 2-squared etc)
//RadStart      worm start radius
//RadEnd        worm end radius
//ExpW          worm radius falloff
//Random        randomness in X,Y and Z directions (vector expression)
//Seed          random number seed

#macro Interpolate(GC,GS,GE,PS,PE,EXP)
        (PS+(PE-PS)*pow((GC-GS)/(GE-GS),EXP))
#end
#declare PointStart = <0,0,0>;
#macro Worm(LenStart, LenEnd, NumSegm, ExpL, RadStart, RadEnd, ExpW, Random, Seed)
        #declare CurSegm = 0;
        #declare PointEnd = <0,0,LenStart>;
        #declare RadConst = RadStart;
        #declare RadAspect = RadEnd/RadStart;
        #declare LenAspect = LenEnd/LenStart;
        #declare MaxTwist = 90;
        #declare R1 = seed(Seed);
        union {
        #while (CurSegm < NumSegm)
                #declare
RadEnd=RadConst*Interpolate(CurSegm+1,0,NumSegm,1,RadAspect,ExpW);
                cone {PointStart, RadStart, PointEnd, RadEnd}
               #declare
PointNew=PointEnd+vrotate(LenStart*vnormalize(PointEnd-PointStart)*Interpolate(CurSegm+1,0,NumSegm,1,LenAspect,ExpL)*1.00001,<0+Random.x*(MaxTwist*rand(R1)-MaxTwist/2),0+Random.y*(MaxTwist*rand(R1)-MaxTwist/2),0+Random.z*(MaxTwist*rand(R1)-MaxTwist/2)>);
                #declare PointStart=PointEnd;
                #declare PointEnd=PointNew;
                #declare RadStart=RadEnd;
                #declare CurSegm=CurSegm+1;
        #end}
#end

object {Worm(.3,0,50,2,.3,0,2,<0,.1,0>,1342) pigment{Red} finish{ambient .3}}

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