Warning: Attempt to read property "date" on null in /usr/local/www/websvn.planix.org/blame.php on line 247

Warning: Attempt to read property "msg" on null in /usr/local/www/websvn.planix.org/blame.php on line 247
WebSVN – planix.SVN – Blame – /os/branches/feature_posix/sys/src/cmd/map/libmap/hex.c – Rev 2

Subversion Repositories planix.SVN

Rev

Go to most recent revision | Details | Last modification | View Log | RSS feed

Rev Author Line No. Line
2 - 1 
#include <u.h>
2 
#include <libc.h>
3 
#include "map.h"
4 
 
5 
#define BIG 1.e15
6 
#define HFUZZ .0001
7 
 
8 
static double hcut[3] ;
9 
static double kr[3] = { .5, -1., .5 };
10 
static double ki[3] = { -1., 0., 1. }; 	/*to multiply by sqrt(3)/2*/
11 
static double cr[3];
12 
static double ci[3];
13 
static struct place hem;
14 
static struct coord twist;
15 
static double  rootroot3, hkc;
16 
static double w2;
17 
static double rootk;
18 
 
19 
static void
20 
reflect(int i, double wr, double wi, double *x, double *y)
21 
{
22 
	double pr,pi,l;
23 
	pr = cr[i]-wr;
24 
	pi = ci[i]-wi;
25 
	l = 2*(kr[i]*pr + ki[i]*pi);
26 
	*x = wr + l*kr[i];
27 
	*y = wi + l*ki[i];
28 
}
29 
 
30 
static int
31 
Xhex(struct place *place, double *x, double *y)
32 
{
33 
	int ns;
34 
	register i;
35 
	double zr,zi;
36 
	double sr,si,tr,ti,ur,ui,vr,vi,yr,yi;
37 
	struct place p;
38 
	copyplace(place,&p);
39 
	ns = place->nlat.l >= 0;
40 
	if(!ns) {
41 
		p.nlat.l = -p.nlat.l;
42 
		p.nlat.s = -p.nlat.s;
43 
	}
44 
	if(p.nlat.l<HFUZZ) {
45 
		for(i=0;i<3;i++)
46 
			if(fabs(reduce(p.wlon.l-hcut[i]))<HFUZZ) {
47 
				if(i==2) {
48 
					*x = 2*cr[0] - cr[1];
49 
					*y = 0;
50 
				} else {
51 
					*x = cr[1];
52 
					*y = 2*ci[2*i];
53 
				}
54 
				return(1);
55 
			}
56 
		p.nlat.l = HFUZZ;
57 
		sincos(&p.nlat);
58 
	}
59 
	norm(&p,&hem,&twist);
60 
	Xstereographic(&p,&zr,&zi);
61 
	zr /= 2;
62 
	zi /= 2;
63 
	cdiv(1-zr,-zi,1+zr,zi,&sr,&si);
64 
	csq(sr,si,&tr,&ti);
65 
	ccubrt(1+3*tr,3*ti,&ur,&ui);
66 
	csqrt(ur-1,ui,&vr,&vi);
67 
	cdiv(rootroot3+vr,vi,rootroot3-vr,-vi,&yr,&yi);
68 
	yr /= rootk;
69 
	yi /= rootk;
70 
	elco2(fabs(yr),yi,hkc,1.,1.,x,y);
71 
	if(yr < 0)
72 
		*x = w2 - *x;
73 
	if(!ns) reflect(hcut[0]>place->wlon.l?0:
74 
			hcut[1]>=place->wlon.l?1:
75 
			2,*x,*y,x,y);
76 
	return(1);
77 
}
78 
 
79 
proj
80 
hex(void)
81 
{
82 
	register i;
83 
	double t;
84 
	double root3;
85 
	double c,d;
86 
	struct place p;
87 
	hcut[2] = PI;
88 
	hcut[1] = hcut[2]/3;
89 
	hcut[0] = -hcut[1];
90 
	root3 = sqrt(3.);
91 
	rootroot3 = sqrt(root3);
92 
	t = 15 -8*root3;
93 
	hkc = t*(1-sqrt(1-1/(t*t)));
94 
	elco2(BIG,0.,hkc,1.,1.,&w2,&t);
95 
	w2 *= 2;
96 
	rootk = sqrt(hkc);
97 
	latlon(90.,90.,&hem);
98 
	latlon(90.,0.,&p);
99 
	Xhex(&p,&c,&t);
100 
	latlon(0.,0.,&p);
101 
	Xhex(&p,&d,&t);
102 
	for(i=0;i<3;i++) {
103 
		ki[i] *= root3/2;
104 
		cr[i] = c + (c-d)*kr[i];
105 
		ci[i] = (c-d)*ki[i];
106 
	}
107 
	deg2rad(0.,&twist);
108 
	return(Xhex);
109 
}
110 
 
111 
int
112 
hexcut(struct place *g, struct place *og, double *cutlon)
113 
{
114 
	int t,i;
115 
	if(g->nlat.l>=-HFUZZ&&og->nlat.l>=-HFUZZ)
116 
		return(1);
117 
	for(i=0;i<3;i++) {
118 
		t = ckcut(g,og,*cutlon=hcut[i]);
119 
		if(t!=1) return(t);
120 
	}
121 
	return(1);
122 
}