BRL-CAD
half_mirror.c
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1 /* H A L F _ 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/half/half_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_half_mirror(struct rt_db_internal *ip, register const plane_t plane)
38 {
39  struct rt_half_internal *half;
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  vect_t n1;
51  vect_t n2;
52 
53  static fastf_t tol_dist_sq = 0.0005 * 0.0005;
54  static point_t origin = {0.0, 0.0, 0.0};
55 
57 
58  half = (struct rt_half_internal *)ip->idb_ptr;
59  RT_HALF_CK_MAGIC(half);
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  /* FIXME: this is not using the mirmat we just computed, not clear
87  * it's even right given it's only taking the mirror direction
88  * into account and not the mirror point.
89  */
90 
91  VMOVE(n1, half->eqn);
92  VCROSS(n2, mirror_dir, n1);
93  VUNITIZE(n2);
94  ang = M_PI_2 - acos(VDOT(n1, mirror_dir));
95  bn_mat_arb_rot(rmat, origin, n2, ang*2);
96  MAT4X3VEC(half->eqn, rmat, n1);
97 
98  if (!NEAR_EQUAL(VDOT(n1, half->eqn), 1.0, tol_dist_sq)) {
99  point_t ptA;
100  point_t ptB;
101  point_t ptC;
102  vect_t h;
103  fastf_t mag;
104  fastf_t cosa;
105 
106  VSCALE(ptA, n1, half->eqn[H]);
107  VADD2(ptB, ptA, mirror_dir);
108  VSUB2(h, ptB, ptA);
109  mag = MAGNITUDE(h);
110  VUNITIZE(h);
111 
112  cosa = VDOT(h, mirror_dir);
113 
114  VSCALE(ptC, half->eqn, -mag * cosa);
115  VADD2(ptC, ptC, ptA);
116  half->eqn[H] = VDOT(half->eqn, ptC);
117  }
118 
119  return 0;
120 }
121 
122 
123 /*
124  * Local Variables:
125  * tab-width: 8
126  * mode: C
127  * indent-tabs-mode: t
128  * c-file-style: "stroustrup"
129  * End:
130  * ex: shiftwidth=4 tabstop=8
131  */
int rt_half_mirror(struct rt_db_internal *ip, register const plane_t plane)
Definition: half_mirror.c:37
#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
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