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As requested my Mr Art and Nekar. Please note that
this macro has problems, it's been on my 'to finish' list
for several months. If anyone makes any imrovements,
please let me know.
Gail
*************************************************************************
* gsh### [at] monotix coza * Step into the abyss, *
* http://www.rucus.ru.ac.za/~gail/ * and let go. Babylon 5 *
*************************************************************************
* The difficult we do immediately, the impossible takes a little longer *
*************************************************************************
// Persistence of Vision Ray Tracer Scene Description File
// File: lightning.inc
// Vers: 3.1
// Desc: Lightning macro
// Date: 3 Sept 2000
// Auth: Gail Shaw
// #version unofficial MegaPov 0.5;
// #include "macros.inc"
/*
Notes:
BranchFreq, Eccentricity and WidthReduct are all percentages.
BranchFreq controls the chance that the lightning bolt will fork at the end
of
each segment. Keep below 20%
The higher the Eccentricity, the larger the angle between bolts.
WidthReduct defines how much narrower each segment should be. It should be
kept
fairly large (>80)
LightningTex is the texture applied to each segment of the lightning bolt.
It is applied before the
segment is translated (Applied to a cylinder lying along the y axis) unless
TextureBefore=0
*/
#macro
Lightning(Start,Length,StartWidth,BranchFreq,Eccentricity,WidthReduct,Lightn
ingTex)
#ifndef (rndLightning)
#local rndLightning=seed(0)
#end
#ifndef (TextureBefore)
#local TextureBefore=1;
#end
#ifndef (Shadow)
#local Shadow=0;
#end
union {
#local UnitLength=Length/50;
#if (abs(UnitLength)<0.00001)
#local UnitLength=0.00001;
#end
// WriteNumber("UnitLength",UnitLength)
#local CurrWidth=StartWidth;
#local CurrLength=0;
#local ZRot=0;
#local XRot=0;
#local CurrEndPos=<0,0,0>;
#while (CurrLength<Length)
#local CurrSegLength= -UnitLength*((rand(rndLightning)/2)+0.5);
#local SegEndPos=<0,CurrSegLength,0>;
cylinder {
<0,0,0>,<0,CurrSegLength,0>,CurrWidth
#if (TextureBefore=1)
texture {LightningTex}
#end
#local ZRot=ZRot/4+(50+Eccentricity/2)*(rand(rndLightning)-0.5);
#local XRot=XRot/4+(50+Eccentricity/2)*(rand(rndLightning)-0.5);
rotate z*ZRot
// WriteNumber ("ZRotation",ZRot)
rotate x*XRot
// WriteNumber ("YRotation",YRot)
// WriteVector("Segment End Pos Before Rot",SegEndPos)
#local SegEndPos=vrotate(SegEndPos,<0,0,ZRot>);
// WriteVector("Segment End Pos afterRotZ",SegEndPos)
#local SegEndPos=vrotate(SegEndPos,<XRot,0,0>);
// WriteVector("Segment End Pos afterRotY",SegEndPos)
translate CurrEndPos
// WriteVector("Current End Pos Before addition",CurrEndPos)
#local CurrEndPos=CurrEndPos+SegEndPos;
// WriteVector("Current End Pos after addition",CurrEndPos)
}
#local Branch=rand(rndLightning)*100;
#if (Branch<BranchFreq)
// WriteNumber("Branching No",Branch)
object {
Lightning(<0,0,0>,Length/2,CurrWidth,BranchFreq/2,Eccentricity,WidthReduct,L
ightningTex)
rotate z*(80+Eccentricity/2)*(rand(rndLightning)-0.5)
rotate x*360*rand(rndLightning)
translate CurrEndPos
}
#end
#local CurrLength= vlength(CurrEndPos);
// WriteNumber("Current Length",CurrLength)
#local CurrWidth=CurrWidth*WidthReduct/100;
#end
sphere {
CurrEndPos,CurrWidth*100/WidthReduct
#if (TextureBefore=1)
texture {LightningTex}
#end
}
#if (TextureBefore=0)
texture {LightningTex}
#end
#if (Shadow=0)
no_shadow
#end
hollow
translate Start
}
#end
camera {
location <0,1,-10>
look_at <0,1,0>
}
light_source {
<0,5,-10>
rgb 1
}
plane {
z,10
hollow
pigment {rgb 0.5}
}
plane {
y,0
hollow
pigment {rgb 0.5}
}
#declare LightTex=
texture {
pigment {rgb 1}
finish {ambient 1}
}
#declare colLeaf_1=rgb <0.7,1,0.2>*0.8; // greenish
#declare colLeaf_2=rgb <1,0.7,0.2>*0.8; // yellow
#declare txtLeaf=texture{pigment{agate color_map{[0.0 color colLeaf_1][0.3
color colLeaf_2] [0.7 color colLeaf_2][1.0 color colLeaf_1] }}
finish{ambient 0.1 specular 0.3 roughness 0.01} scale 0.1}
#declare rndLightning=seed(24);
//
Lightning(Start,Length,StartWidth,BranchFreq,Eccentricity,WidthReduct,Lightn
ingTex)
#declare TextureBefore=0;
#declare Shadow=0;
object {
Lightning(<0,2,0>,2,0.02,3,90,99,LightTex)
scale 2
}
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