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Christmas Postcard 2008 in PostScript
%!PS-Adobe-3.0
%%BeginFeature: *PageSize A4
<< /PageSize [595 842] >> setpagedevice
%%EndFeature
%/PageSize A4
/CoordX 595 def
/CoordY 842 def
/RadiMax 95 def
/Margin 25 def
/NumThings 900 def
newpath
Margin Margin moveto
CoordX Margin sub Margin lineto
CoordX Margin sub CoordY Margin sub lineto
Margin CoordY Margin sub lineto
Margin Margin lineto
closepath
gsave
0.08235 0.0352 0.17842 setrgbcolor
fill
grestore
clip
%%% GOSPER-START
%%% Start of L-system definition
/STARTG { FG XG } def
/XG {
%(XG) = stack () =
dup 0 eq { DG } { 1 sub 7 {dup} repeat
XG +G Y FG +G +G Y FG
-G FG XG -G -G FG XG FG
XG -G Y FG +G } ifelse pop } bind def
/Y {
%(Y) = stack () =
dup 0 eq { DG } { 1 sub 7 {dup} repeat
-G FG XG +G Y FG Y FG
+G +G Y FG +G FG XG -G
-G FG XG -G Y } ifelse pop } bind def
/FG {
DG
} bind def
/angleG 60 def
/-G { % rotation to the right
angleG neg rotate
} bind def
/+G { % rotation to the left
angleG rotate
} bind def
%%% End of L-System definition
/scalefactor {7 sqrt orderG exp} bind def
/DG { 100 1.3 div scalefactor div 0 rlineto } bind def
%%% Scaling factors
/GosperSize 100 def
/thickness {1 orderG dup mul div} bind def
/angleC 27 def
/orderG 1 def
%%% More scaling factors, angle of rotation depending on
%%% the order
%%% Draws a radius 100 Gosper Island at 0 0
/Gosper100
{
gsave
newpath
-400 -400 translate
400 400
thickness setlinewidth
orderG angleC 3 add orderG sub mul
cos GosperSize mul sub exch
orderG angleC 3 add orderG sub mul
sin GosperSize mul sub
moveto
orderG STARTG
Colorize
stroke
closepath
grestore
} def % Receives nothing
%%% Draws an arbitrary Gosper Island
/Gosper {
/orderG exch store
gsave
3 1 roll
translate
100 div
dup
scale
rand 360 mod rotate
Gosper100
grestore
} def % Receives x y size order
%%% GOSPER-END
%%% KOCH-START
%%% Start of L-system definition
/STARTK { FK +K +K FK +K +K FK} def
/FK {
dup 0 eq
{ DK } % if the recursion order ends, draw forward
{
1 sub % recurse
4 {dup} repeat % dup the number of parameters (order) needed.
FK -K FK +K +K FK -K FK }
ifelse
pop % pop the dup'd order
} bind def
/angleK 60 def
/-K { % rotation to the right
angleK neg rotate
} bind def
/+K { % rotation to the left
angleK rotate
} bind def
%%% End of L-System definition
/DK { sizeK 3 orderK exp div 0 rlineto } bind def
/thicknessK {1 orderK dup mul div} bind def
%%% Scaling factors
/orderK 3 def
/sizeK 300 def
%%% Draws a Koch's snowflake of radius 180 at 0 0
/Koch180 {
gsave
newpath
thicknessK setlinewidth
200 300 60 cos mul add
neg
200 100 60 sin mul add
neg
translate
200 200 moveto
orderK orderK orderK STARTK
Colorize
stroke
closepath
grestore
} def % receives nothing
%%% Draws an arbitrary Koch's snowflake
/Koch {
/orderK exch store
gsave
3 1 roll
translate
180 div dup scale
rand 360 mod rotate
Koch180
grestore
} def % Receives x y size order
%%% KOCH-END
%%% LINED-START
%%% Generates a lined star at 0 0 of radius 100
/star100
{
gsave
newpath
360 exch div dup dup dup dup %Angle
cos 100 mul
exch sin 100 mul exch
5 2 roll 360 add {
%(FORRRR) =
%stack
%(FORRRR) =
dup
cos 100 mul
exch sin 100 mul exch
2 copy
0 0 8 6 roll
orderL linies
} for
closepath
pop pop
Colorize
stroke
grestore
} def % Receives Number of Spikes
/orderL 1 def
/star
{
rand 11 mod 10 add /orderL exch store
gsave
4 2 roll
translate
exch
100 div dup scale
rand 360 mod rotate
star100
grestore
} def % Receives Position, Radius, Number of Spikes
/dist
{
sub dup mul
3 1 roll
sub dup mul
add
sqrt
} def
/linies
{
/num exch def
/y3 exch def
/x3 exch def
/y2 exch def
/x2 exch def
/y1 exch def
/x1 exch def
/incr 1 num div def
0 1 num {
/pos exch def
x2 x1 sub incr pos mul mul x1 add
y2 y1 sub incr pos mul mul y1 add
moveto
x3 x2 sub incr pos mul mul x2 add
y3 y2 sub incr pos mul mul y2 add
lineto
%stroke
} for
} def % Receives Point1, centerpoint, Point2, numberOfSegments
%%% LINED-END
/Colorize
{
rand 20 mod 1 add 1 exch div
0.3 mul
0.2 add
rand 20 mod 1 add 1 exch div
0.3 mul
0.2 add
rand 20 mod 1 add 1 exch div
0.3 mul
0.2 add
setrgbcolor
} def
/CouldDraw
{
% stack state xn yn rn xn-1 yn-1 rn-1
exch % xn yn rn xn-1 rn-1 yn-1
4 index % xn yn rn xn-1 rn-1 yn-1 yn
sub dup mul % xn yn rn xn-1 rn-1 (yn-1-yn)^2
3 1 roll % xn yn rn (yn-1-yn)^2 xn-1 rn-1
exch % xn yn rn (yn-1-yn)^2 rn-1 xn-1
5 index % xn yn rn (yn-1-yn)^2 rn-1 xn-1 xn
sub dup mul
exch % xn yn rn (yn-1-yn)^2 (xn-xn-1)^2 rn-1
3 1 roll % xn yn rn rn-1 (yn-1-yn)^2 (xn-xn-1)^2
add sqrt % xn yn rn rn-1 d(C_n, C_{n-1})
exch % xn yn rn d(C_n, C_{n-1}) rn-1
2 index % xn yn rn d(C_n, C_{n-1}) rn-1 rn
add
gt
{true}{false} ifelse
% now the stack loses nothing
} def
realtime srand
1 1 NumThings {
/n exch def % Counter for the number of elements
rand
CoordX mod
rand
CoordY mod % random coordinates
rand
RadiMax mod 5 add % random radius
true
1 1 n 1 sub {
exch
n 3 mul 2 add 1 roll % Move the default true to the bottom of
% the "coordinate stack, or the previous
% true/false condition. Now the stack has
% all points and the new point
3 mul 4 add % Start from the bottom of the stack, and add
% the current elements. Keep in mind, index
% doesn't count the element!
dup dup % We need 3 like this
index % Stack xn yn rn 3m+6 3m+6 xn-1
3 1 roll % Stack xn yn rn xn-1 3m+6 3m+6
1 sub
index % Stack xn yn rn xn-1 3m+6 yn-1
exch % Stack xn yn rn xn-1 yn-1 3m+6
2 sub
index % Stack xn yn rn xn-1 yn-1 rn-1
CouldDraw
}for
% Now the stack is filled with n-1 true/false conditions and the
% 3n elements corresponding to circle coordinates+radii, followed
% by the last true/false.
n 1 eq {} {
3 n mul 1 add 1 roll % All t/f together
n 4 mul 3 n mul roll % All t/f on top
n 1 sub {and} repeat} % Convert to one condition
ifelse
{
3 copy
%3 copy % Uncomment this to add bounding circles
rand 2 mod
1 eq
{
rand 2 mod 1 eq
{
rand 6 mod 4 add % Random number of spikes
star
}
{
rand 4 mod 2 add % Random order, between 2 and 5
Koch
} ifelse
}
{
rand 3 mod 2 add % Random order, between 2 and 4
Gosper
}
ifelse
%newpath % Uncomment all these to add bounding circles
%0 360 arc
%stroke
%closepath
}
{
3 {pop} repeat
3 copy
}
ifelse
} for
showpage
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