BRL-CAD
grip_mirror.c
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1 /* G R I P _ M I R R O R . C
2  * BRL-CAD
3  *
4  * Copyright (c) 2009-2014 United States Government as represented by
5  * the U.S. Army Research Laboratory.
6  *
7  * This library is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public License
9  * version 2.1 as published by the Free Software Foundation.
10  *
11  * This library is distributed in the hope that it will be useful, but
12  * WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this file; see the file named COPYING for more
18  * information.
19  */
20 /** @file primitives/grip/grip_mirror.c
21  *
22  * mirror support
23  *
24  */
25 
26 #include "common.h"
27 
28 #include "raytrace.h"
29 #include "rtgeom.h"
30 
31 
32 /**
33  * Given a pointer to an internal GED database object, mirror the
34  * object's values about the given transformation matrix.
35  */
36 int
37 rt_grip_mirror(struct rt_db_internal *ip, register const plane_t plane)
38 {
39  struct rt_grip_internal *grip;
40 
41  mat_t mirmat;
42  mat_t rmat;
43  mat_t temp;
44  vect_t nvec;
45  vect_t xvec;
46  vect_t mirror_dir;
47  point_t mirror_pt;
48  fastf_t ang;
49 
50  point_t pt;
51  vect_t h;
52  vect_t n;
53 
54  static point_t origin = {0.0, 0.0, 0.0};
55 
57 
58  grip = (struct rt_grip_internal *)ip->idb_ptr;
59  RT_GRIP_CK_MAGIC(grip);
60 
61  MAT_IDN(mirmat);
62 
63  VMOVE(mirror_dir, plane);
64  VSCALE(mirror_pt, plane, plane[W]);
65 
66  /* Build mirror transform matrix, for those who need it. */
67  /* First, perform a mirror down the X axis */
68  mirmat[0] = -1.0;
69 
70  /* Create the rotation matrix */
71  VSET(xvec, 1, 0, 0);
72  VCROSS(nvec, xvec, mirror_dir);
73  VUNITIZE(nvec);
74  ang = -acos(VDOT(xvec, mirror_dir));
75  bn_mat_arb_rot(rmat, origin, nvec, ang*2.0);
76 
77  /* Add the rotation to mirmat */
78  MAT_COPY(temp, mirmat);
79  bn_mat_mul(mirmat, temp, rmat);
80 
81  /* Add the translation to mirmat */
82  mirmat[3 + X*4] += mirror_pt[X] * mirror_dir[X];
83  mirmat[3 + Y*4] += mirror_pt[Y] * mirror_dir[Y];
84  mirmat[3 + Z*4] += mirror_pt[Z] * mirror_dir[Z];
85 
86  VMOVE(pt, grip->center);
87  MAT4X3PNT(grip->center, mirmat, pt);
88 
89  VMOVE(h, grip->normal);
90  VUNITIZE(h);
91 
92  /* FIXME: doesn't seem right that we're computing another angle
93  * here.
94  */
95 
96  VCROSS(n, mirror_dir, grip->normal);
97  VUNITIZE(n);
98  ang = M_PI_2 - acos(VDOT(h, mirror_dir));
99  bn_mat_arb_rot(rmat, origin, n, ang*2);
100  MAT4X3VEC(grip->normal, rmat, h);
101 
102  return 0;
103 }
104 
105 
106 /*
107  * Local Variables:
108  * tab-width: 8
109  * mode: C
110  * indent-tabs-mode: t
111  * c-file-style: "stroustrup"
112  * End:
113  * ex: shiftwidth=4 tabstop=8
114  */
#define VSET(a, b, c, d)
Definition: color.c:53
Header file for the BRL-CAD common definitions.
Definition: color.c:49
#define RT_CK_DB_INTERNAL(_p)
Definition: raytrace.h:207
void bn_mat_mul(mat_t o, const mat_t a, const mat_t b)
void * idb_ptr
Definition: raytrace.h:195
Definition: color.c:51
double fastf_t
Definition: defines.h:300
int rt_grip_mirror(struct rt_db_internal *ip, register const plane_t plane)
Definition: grip_mirror.c:37
void bn_mat_arb_rot(mat_t m, const point_t pt, const vect_t dir, const fastf_t ang)
Definition: mat.c:987
Definition: color.c:50