Task: Dragon curve

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>


long long x, y, dx, dy, scale, clen;
typedef struct { double r, g, b; } rgb;
rgb ** pix;


void sc_up()
{
	long long tmp = dx - dy; dy = dx + dy; dx = tmp;
	scale *= 2; x *= 2; y *= 2;
}


void h_rgb(long long x, long long y)
{
	rgb *p = &pix[y][x];

#	define SAT 1
	double h = 6.0 * clen / scale;
	double VAL = 1 - (cos(3.141592653579 * 64 * clen / scale) - 1) / 4;
	double c = SAT * VAL;
	double X = c * (1 - fabs(fmod(h, 2) - 1));

	switch((int)h) {
	case 0: p->r += c; p->g += X; return;
	case 1:	p->r += X; p->g += c; return;
	case 2: p->g += c; p->b += X; return;
	case 3: p->g += X; p->b += c; return;
	case 4: p->r += X; p->b += c; return;
	default:
		p->r += c; p->b += X;
	}
}


void iter_string(const char * str, int d)
{
	long tmp;
#	define LEFT  tmp = -dy; dy = dx; dx = tmp
#	define RIGHT tmp = dy; dy = -dx; dx = tmp
	while (*str != '\0') {
		switch(*(str++)) {
		case 'X':	if (d) iter_string("X+YF+", d - 1); continue;
		case 'Y':	if (d) iter_string("-FX-Y", d - 1); continue;
		case '+':	RIGHT; continue;
		case '-':	LEFT;  continue;
		case 'F':
                        
				clen ++;
				h_rgb(x/scale, y/scale);
				x += dx; y += dy;
				continue;
		}
	}
}

void dragon(long leng, int depth)
{
	long i, d = leng / 3 + 1;
	long h = leng + 3, w = leng + d * 3 / 2 + 2;

	
	rgb *buf = malloc(sizeof(rgb) * w * h);
	pix = malloc(sizeof(rgb *) * h);
	for (i = 0; i < h; i++)
		pix[i] = buf + w * i;
	memset(buf, 0, sizeof(rgb) * w * h);

        
	x = y = d; dx = leng; dy = 0; scale = 1; clen = 0;
	for (i = 0; i < depth; i++) sc_up();
	iter_string("FX", depth);

	
	unsigned char *fpix = malloc(w * h * 3);
	double maxv = 0, *dbuf = (double*)buf;

        
	for (i = 3 * w * h - 1; i >= 0; i--)
		if (dbuf[i] > maxv) maxv = dbuf[i];
	for (i = 3 * h * w - 1; i >= 0; i--)
		fpix[i] = 255 * dbuf[i] / maxv;

	printf("P6\n%ld %ld\n255\n", w, h);
	fflush(stdout); 
	fwrite(fpix, h * w * 3, 1, stdout);
}

int main(int c, char ** v)
{
	int size, depth;

	depth  = (c > 1) ? atoi(v[1]) : 10;
	size = 1 << depth;

	fprintf(stderr, "size: %d depth: %d\n", size, depth);
	dragon(size, depth * 2);

	return 0;
}








VB: option explicit


const pi180= 0.01745329251994329576923690768489 
const pi=3.1415926535897932384626433832795 
class turtle
   
   dim fso
   dim fn
   dim svg
   
   dim iang  
   dim ori   
   dim incr
   dim pdown
   dim clr
   dim x
   dim y

   public property let orient(n):ori = n*pi180 :end property
   public property let iangle(n):iang= n*pi180 :end property
   public sub pd() : pdown=true: end sub 
   public sub pu()  :pdown=FALSE :end sub 
   
   public sub rt(i)  
     ori=ori - i*iang:
     
   end sub 
   public sub lt(i):  
     ori=(ori + i*iang) 
     
   end sub
   
   public sub bw(l)
      x= x+ cos(ori+pi)*l*incr
      y= y+ sin(ori+pi)*l*incr
     
   end sub 
   
   public sub fw(l)
      dim x1,y1 
      x1=x + cos(ori)*l*incr
      y1=y + sin(ori)*l*incr
      if pdown then line x,y,x1,y1
      x=x1:y=y1
   end sub
   
   Private Sub Class_Initialize()  
      setlocale "us"   
      initsvg
      x=400:y=400:incr=100
      ori=90*pi180
      iang=90*pi180
      clr=0
      pdown=true
   end sub
   
   Private Sub Class_Terminate()   
      disply
   end sub
   
   private sub line (x,y,x1,y1)
      svg.WriteLine "<line x1=""" & x & """ y1= """& y & """ x2=""" & x1& """ y2=""" & y1 & """/>"
   end sub 

   private sub disply()
       dim shell
       svg.WriteLine "</svg></body></html>"
       svg.close
       Set shell = CreateObject("Shell.Application") 
       shell.ShellExecute fn,1,False
   end sub 

   private sub initsvg()
     dim scriptpath
     Set fso = CreateObject ("Scripting.Filesystemobject")
     ScriptPath= Left(WScript.ScriptFullName, InStrRev(WScript.ScriptFullName, "\"))
     fn=Scriptpath & "SIERP.HTML"
     Set svg = fso.CreateTextFile(fn,True)
     if SVG IS nothing then wscript.echo "Can
     svg.WriteLine "<!DOCTYPE html>" &vbcrlf & "<html>" &vbcrlf & "<head>"
     svg.writeline "<style>" & vbcrlf & "line {stroke:rgb(255,0,0);stroke-width:.5}" &vbcrlf &"</style>"
     svg.writeline "</head>"&vbcrlf & "<body>"
     svg.WriteLine "<svg xmlns=""http://www.w3.org/2000/svg"" width=""800"" height=""800"" viewBox=""0 0 800 800"">" 
   end sub 
end class

sub dragon(st,le,dir)
if st=0 then x.fw le: exit sub
  x.rt dir
  dragon st-1, le/1.41421 ,1
  x.rt dir*2
  dragon st-1, le/1.41421 ,-1
  x.rt dir
end sub

 
dim x
set x=new turtle
x.iangle=45
x.orient=45
x.incr=1
x.x=200:x.y=200
dragon 12,300,1
set x=nothing