Sierpinski curve: Difference between revisions

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Uses Image Magick and

the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl

<lang zkl>~~sierpinskiArrowheadCurve~~(5) : turtle(_);

<lang zkl>sierpinskiCurve(5) : turtle(_,45,45); // n=5 --> 11,606 characters

fcn sierpinskiCurve(order){

fcn sierpinskiArrowheadCurve(n){ // Lindenmayer system --> Data of As & Bs

LSystem("F--XF--F--XF",Dictionary("X","XF+G+XF--F--XF+G+X"), order)

var [const] A="AF+G+AF--F--AF+G+A", B=""; // Production rules

}

var [const] Axiom="F--AF--F--AF";

fcn LSystem(axiom,rules,order){ // Lindenmayer system

buf1,buf2 := Data(Void,~~Axiom~~).howza(3), Data().howza(3); // characters

buf1,buf2 := Data(Void,axiom).howza(3), Data().howza(3); // characters

do(n){

do(order){

buf1.pump(buf2.clear(),~~fcn~~(c){ if(c=~~="A") A else if~~(c~~=="B"~~) B else c });

buf1.pump(buf2.clear(),'wrap(c){ if(a:=rules.find(c)) a else c });

t:=buf1; buf1=buf2; buf2=t; // swap buffers

}

buf1

buf1 // n=5 --> 11,606 characters

}

fcn turtle(curve){ // ~~Turtle with that can~~ ~~turn~~ +-45*

fcn turtle(curve,angle,startAngle){ // angles in degrees

const D=10.0~~, a45=45~~;

const D=10.0;

dir:=startAngle;

dir:=a45; // start direction depends on order

img,color := PPM(800,800), 0x00ff00; // green on black

x,y := 15, img.h - x;

foreach c in (curve){ ~~// A & B are no-op during drawing~~

foreach c in (curve){

switch(c){

case("F","G"){ // draw forward

Line 451:

Line 452:

img.line(x,y, (x+=a.round()),(y+=b.round()), color)

}

case("+"){ dir=(dir + ~~a45~~)%360; } // turn left 45*

case("+"){ dir=(dir + angle)%360; } // turn left angle

case("-"){ dir=(dir - ~~a45~~)%360; } // turn right 45*

case("-"){ dir=(dir - angle)%360; } // turn right angle

}