1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
/*
* Copyright 2016-2018 Uber Technologies, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/** @file coordijk.h
* @brief Header file for CoordIJK functions including conversion from lat/lon
*
* References two Vec2d cartesian coordinate systems:
*
* 1. gnomonic: face-centered polyhedral gnomonic projection space with
* traditional scaling and x-axes aligned with the face Class II
* i-axes.
*
* 2. hex2d: local face-centered coordinate system scaled a specific H3 grid
* resolution unit length and with x-axes aligned with the local
* i-axes
*/
#ifndef COORDIJK_H
#define COORDIJK_H
#include "geoCoord.h"
#include "h3api.h"
#include "vec2d.h"
/** @struct CoordIJK
* @brief IJK hexagon coordinates
*
* Each axis is spaced 120 degrees apart.
*/
typedef struct {
int i; ///< i component
int j; ///< j component
int k; ///< k component
} CoordIJK;
/** @brief CoordIJK unit vectors corresponding to the 7 H3 digits.
*/
static const CoordIJK UNIT_VECS[] = {
{0, 0, 0}, // direction 0
{0, 0, 1}, // direction 1
{0, 1, 0}, // direction 2
{0, 1, 1}, // direction 3
{1, 0, 0}, // direction 4
{1, 0, 1}, // direction 5
{1, 1, 0} // direction 6
};
/** @brief H3 digit representing ijk+ axes direction.
* Values will be within the lowest 3 bits of an integer.
*/
typedef enum {
/** H3 digit in center */
CENTER_DIGIT = 0,
/** H3 digit in k-axes direction */
K_AXES_DIGIT = 1,
/** H3 digit in j-axes direction */
J_AXES_DIGIT = 2,
/** H3 digit in j == k direction */
JK_AXES_DIGIT = J_AXES_DIGIT | K_AXES_DIGIT, /* 3 */
/** H3 digit in i-axes direction */
I_AXES_DIGIT = 4,
/** H3 digit in i == k direction */
IK_AXES_DIGIT = I_AXES_DIGIT | K_AXES_DIGIT, /* 5 */
/** H3 digit in i == j direction */
IJ_AXES_DIGIT = I_AXES_DIGIT | J_AXES_DIGIT, /* 6 */
/** H3 digit in the invalid direction */
INVALID_DIGIT = 7,
/** Valid digits will be less than this value. Same value as INVALID_DIGIT.
*/
NUM_DIGITS = INVALID_DIGIT
} Direction;
// Internal functions
void _setIJK(CoordIJK* ijk, int i, int j, int k);
void _hex2dToCoordIJK(const Vec2d* v, CoordIJK* h);
void _ijkToHex2d(const CoordIJK* h, Vec2d* v);
int _ijkMatches(const CoordIJK* c1, const CoordIJK* c2);
void _ijkAdd(const CoordIJK* h1, const CoordIJK* h2, CoordIJK* sum);
void _ijkSub(const CoordIJK* h1, const CoordIJK* h2, CoordIJK* diff);
void _ijkScale(CoordIJK* c, int factor);
void _ijkNormalize(CoordIJK* c);
Direction _unitIjkToDigit(const CoordIJK* ijk);
void _upAp7(CoordIJK* ijk);
void _upAp7r(CoordIJK* ijk);
void _downAp7(CoordIJK* ijk);
void _downAp7r(CoordIJK* ijk);
void _downAp3(CoordIJK* ijk);
void _downAp3r(CoordIJK* ijk);
void _neighbor(CoordIJK* ijk, Direction digit);
void _ijkRotate60ccw(CoordIJK* ijk);
void _ijkRotate60cw(CoordIJK* ijk);
Direction _rotate60ccw(Direction digit);
Direction _rotate60cw(Direction digit);
int ijkDistance(const CoordIJK* a, const CoordIJK* b);
void ijkToIj(const CoordIJK* ijk, CoordIJ* ij);
void ijToIjk(const CoordIJ* ij, CoordIJK* ijk);
void ijkToCube(CoordIJK* ijk);
void cubeToIjk(CoordIJK* ijk);
#endif
|
