1 |
greg |
2.1 |
#ifndef lint |
2 |
greg |
2.2 |
static const char RCSid[] = "$Id$"; |
3 |
greg |
2.1 |
#endif |
4 |
|
|
/* |
5 |
|
|
* Compute 4-byte direction code (assume this fits into int) |
6 |
|
|
*/ |
7 |
|
|
|
8 |
|
|
#include "standard.h" |
9 |
|
|
|
10 |
|
|
#define DCSCALE 11585.2 /* (1<<13)*sqrt(2) */ |
11 |
|
|
#define FXNEG 01 |
12 |
|
|
#define FYNEG 02 |
13 |
|
|
#define FZNEG 04 |
14 |
|
|
#define F1X 010 |
15 |
|
|
#define F2Z 020 |
16 |
|
|
#define F1SFT 5 |
17 |
|
|
#define F2SFT 18 |
18 |
|
|
#define FMASK 0x1fff |
19 |
|
|
|
20 |
|
|
int4 |
21 |
|
|
encodedir(dv) /* encode a normalized direction vector */ |
22 |
|
|
FVECT dv; |
23 |
|
|
{ |
24 |
|
|
register int4 dc = 0; |
25 |
|
|
int cd[3], cm; |
26 |
|
|
register int i; |
27 |
|
|
|
28 |
|
|
for (i = 0; i < 3; i++) |
29 |
|
|
if (dv[i] < 0.) { |
30 |
|
|
cd[i] = dv[i] * -DCSCALE; |
31 |
|
|
dc |= FXNEG<<i; |
32 |
|
|
} else |
33 |
|
|
cd[i] = dv[i] * DCSCALE; |
34 |
|
|
if (cd[0] <= cd[1]) { |
35 |
|
|
dc |= F1X | cd[0] << F1SFT; |
36 |
|
|
cm = cd[1]; |
37 |
|
|
} else { |
38 |
|
|
dc |= cd[1] << F1SFT; |
39 |
|
|
cm = cd[0]; |
40 |
|
|
} |
41 |
|
|
if (cd[2] <= cm) |
42 |
|
|
dc |= F2Z | cd[2] << F2SFT; |
43 |
|
|
else |
44 |
|
|
dc |= cm << F2SFT; |
45 |
greg |
2.2 |
if (!dc) /* don't generate 0 code */ |
46 |
|
|
dc = F1X; |
47 |
greg |
2.1 |
return(dc); |
48 |
|
|
} |
49 |
|
|
|
50 |
|
|
|
51 |
|
|
void |
52 |
|
|
decodedir(dv, dc) /* decode a normalized direction vector */ |
53 |
|
|
register FVECT dv; /* returned */ |
54 |
|
|
register int4 dc; |
55 |
|
|
{ |
56 |
|
|
double d1, d2, der; |
57 |
|
|
|
58 |
|
|
d1 = ((dc>>F1SFT & FMASK)+.5)*(1./DCSCALE); |
59 |
|
|
d2 = ((dc>>F2SFT & FMASK)+.5)*(1./DCSCALE); |
60 |
|
|
der = sqrt(1. - d1*d1 - d2*d2); |
61 |
|
|
if (dc & F1X) { |
62 |
|
|
dv[0] = d1; |
63 |
|
|
if (dc & F2Z) { dv[1] = der; dv[2] = d2; } |
64 |
|
|
else { dv[1] = d2; dv[2] = der; } |
65 |
|
|
} else { |
66 |
|
|
dv[1] = d1; |
67 |
|
|
if (dc & F2Z) { dv[0] = der; dv[2] = d2; } |
68 |
|
|
else { dv[0] = d2; dv[2] = der; } |
69 |
|
|
} |
70 |
|
|
if (dc & FXNEG) dv[0] = -dv[0]; |
71 |
|
|
if (dc & FYNEG) dv[1] = -dv[1]; |
72 |
|
|
if (dc & FZNEG) dv[2] = -dv[2]; |
73 |
|
|
} |
74 |
|
|
|
75 |
|
|
|
76 |
|
|
double |
77 |
|
|
dir2diff(dc1, dc2) /* approx. radians^2 between directions */ |
78 |
|
|
int4 dc1, dc2; |
79 |
|
|
{ |
80 |
|
|
FVECT v1, v2; |
81 |
|
|
|
82 |
|
|
decodedir(v1, dc1); |
83 |
|
|
decodedir(v2, dc2); |
84 |
|
|
|
85 |
|
|
return(2. - 2.*DOT(v1,v2)); |
86 |
|
|
} |
87 |
|
|
|
88 |
|
|
|
89 |
|
|
double |
90 |
|
|
fdir2diff(dc1, v2) /* approx. radians^2 between directions */ |
91 |
|
|
int4 dc1; |
92 |
|
|
register FVECT v2; |
93 |
|
|
{ |
94 |
|
|
FVECT v1; |
95 |
|
|
|
96 |
|
|
decodedir(v1, dc1); |
97 |
|
|
|
98 |
|
|
return(2. - 2.*DOT(v1,v2)); |
99 |
|
|
} |