RDKit
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Conrec.h
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1 //
2 // Copyright (C) 2019 Greg Landrum
3 //
4 // @@ All Rights Reserved @@
5 // This file is part of the RDKit.
6 // The contents are covered by the terms of the BSD license
7 // which is included in the file license.txt, found at the root
8 // of the RDKit source tree.
9 //
10 #include <vector>
11 #include <Geometry/point.h>
12 
13 namespace conrec {
14 struct ConrecSegment {
17  double isoVal;
18  ConrecSegment(double x1, double y1, double x2, double y2, double isoVal)
19  : p1(x1, y1), p2(x2, y2), isoVal(isoVal) {}
21  double isoVal)
22  : p1(p1), p2(p2), isoVal(isoVal) {}
23 };
24 // adapted from conrec.c by Paul Bourke:
25 // http://paulbourke.net/papers/conrec/conrec.c
26 /*
27  Derivation from the fortran version of CONREC by Paul Bourke
28  d ! matrix of data to contour
29  ilb,iub,jlb,jub ! index bounds of data matrix
30  x ! data matrix column coordinates
31  y ! data matrix row coordinates
32  nc ! number of contour levels
33  z ! contour levels in increasing order
34 */
35 inline void Contour(const double *d, size_t ilb, size_t iub, size_t jlb,
36  size_t jub, const double *x, const double *y, size_t nc,
37  double *z, std::vector<ConrecSegment> &res) {
38  PRECONDITION(d, "no data");
39  PRECONDITION(x, "no data");
40  PRECONDITION(y, "no data");
41  PRECONDITION(z, "no data");
42  PRECONDITION(nc > 0, "no contours");
43  PRECONDITION(iub > ilb, "bad bounds");
44  PRECONDITION(jub > jlb, "bad bounds");
45 
46  int m1, m2, m3, case_value;
47  double dmin, dmax, x1 = 0, x2 = 0, y1 = 0, y2 = 0;
48  int i, j, m;
49  size_t k;
50  double h[5];
51  int sh[5];
52  double xh[5], yh[5];
53  int im[4] = {0, 1, 1, 0}, jm[4] = {0, 0, 1, 1};
54  int castab[3][3][3] = {{{0, 0, 8}, {0, 2, 5}, {7, 6, 9}},
55  {{0, 3, 4}, {1, 3, 1}, {4, 3, 0}},
56  {{9, 6, 7}, {5, 2, 0}, {8, 0, 0}}};
57  double temp1, temp2;
58  size_t ny = jub - jlb + 1;
59 
60  auto xsect = [&](int p1, int p2) {
61  return (h[p2] * xh[p1] - h[p1] * xh[p2]) / (h[p2] - h[p1]);
62  };
63  auto ysect = [&](int p1, int p2) {
64  return (h[p2] * yh[p1] - h[p1] * yh[p2]) / (h[p2] - h[p1]);
65  };
66 
67  for (j = (jub - 1); j >= (int)jlb; j--) {
68  for (i = ilb; i <= (int)iub - 1; i++) {
69  temp1 = std::min(d[i * ny + j], d[i * ny + j + 1]);
70  temp2 = std::min(d[(i + 1) * ny + j], d[(i + 1) * ny + j + 1]);
71  dmin = std::min(temp1, temp2);
72  temp1 = std::max(d[i * ny + j], d[i * ny + j + 1]);
73  temp2 = std::max(d[(i + 1) * ny + j], d[(i + 1) * ny + j + 1]);
74  dmax = std::max(temp1, temp2);
75  if (dmax < z[0] || dmin > z[nc - 1]) continue;
76  for (k = 0; k < nc; k++) {
77  if (z[k] < dmin || z[k] > dmax) continue;
78  for (m = 4; m >= 0; m--) {
79  if (m > 0) {
80  h[m] = d[(i + im[m - 1]) * ny + j + jm[m - 1]] - z[k];
81  xh[m] = x[i + im[m - 1]];
82  yh[m] = y[j + jm[m - 1]];
83  } else {
84  h[0] = 0.25 * (h[1] + h[2] + h[3] + h[4]);
85  xh[0] = 0.50 * (x[i] + x[i + 1]);
86  yh[0] = 0.50 * (y[j] + y[j + 1]);
87  }
88  if (h[m] > 0.0)
89  sh[m] = 1;
90  else if (h[m] < 0.0)
91  sh[m] = -1;
92  else
93  sh[m] = 0;
94  }
95 
96  /*
97  Note: at this stage the relative heights of the corners and the
98  centre are in the h array, and the corresponding coordinates are
99  in the xh and yh arrays. The centre of the box is indexed by 0
100  and the 4 corners by 1 to 4 as shown below.
101  Each triangle is then indexed by the parameter m, and the 3
102  vertices of each triangle are indexed by parameters m1,m2,and m3.
103  It is assumed that the centre of the box is always vertex 2
104  though this isimportant only when all 3 vertices lie exactly on
105  the same contour level, in which case only the side of the box
106  is drawn.
107  vertex 4 +-------------------+ vertex 3
108  | \ / |
109  | \ m-3 / |
110  | \ / |
111  | \ / |
112  | m=2 X m=2 | the centre is vertex 0
113  | / \ |
114  | / \ |
115  | / m=1 \ |
116  | / \ |
117  vertex 1 +-------------------+ vertex 2
118  */
119  /* Scan each triangle in the box */
120  for (m = 1; m <= 4; m++) {
121  m1 = m;
122  m2 = 0;
123  if (m != 4)
124  m3 = m + 1;
125  else
126  m3 = 1;
127  if ((case_value = castab[sh[m1] + 1][sh[m2] + 1][sh[m3] + 1]) == 0)
128  continue;
129  switch (case_value) {
130  case 1: /* Line between vertices 1 and 2 */
131  x1 = xh[m1];
132  y1 = yh[m1];
133  x2 = xh[m2];
134  y2 = yh[m2];
135  break;
136  case 2: /* Line between vertices 2 and 3 */
137  x1 = xh[m2];
138  y1 = yh[m2];
139  x2 = xh[m3];
140  y2 = yh[m3];
141  break;
142  case 3: /* Line between vertices 3 and 1 */
143  x1 = xh[m3];
144  y1 = yh[m3];
145  x2 = xh[m1];
146  y2 = yh[m1];
147  break;
148  case 4: /* Line between vertex 1 and side 2-3 */
149  x1 = xh[m1];
150  y1 = yh[m1];
151  x2 = xsect(m2, m3);
152  y2 = ysect(m2, m3);
153  break;
154  case 5: /* Line between vertex 2 and side 3-1 */
155  x1 = xh[m2];
156  y1 = yh[m2];
157  x2 = xsect(m3, m1);
158  y2 = ysect(m3, m1);
159  break;
160  case 6: /* Line between vertex 3 and side 1-2 */
161  x1 = xh[m3];
162  y1 = yh[m3];
163  x2 = xsect(m1, m2);
164  y2 = ysect(m1, m2);
165  break;
166  case 7: /* Line between sides 1-2 and 2-3 */
167  x1 = xsect(m1, m2);
168  y1 = ysect(m1, m2);
169  x2 = xsect(m2, m3);
170  y2 = ysect(m2, m3);
171  break;
172  case 8: /* Line between sides 2-3 and 3-1 */
173  x1 = xsect(m2, m3);
174  y1 = ysect(m2, m3);
175  x2 = xsect(m3, m1);
176  y2 = ysect(m3, m1);
177  break;
178  case 9: /* Line between sides 3-1 and 1-2 */
179  x1 = xsect(m3, m1);
180  y1 = ysect(m3, m1);
181  x2 = xsect(m1, m2);
182  y2 = ysect(m1, m2);
183  break;
184  default:
185  break;
186  }
187 
188  /* Finally draw the line */
189  res.emplace_back(RDGeom::Point2D(x1, y1), RDGeom::Point2D(x2, y2),
190  z[k]);
191  } /* m */
192  } /* k - contour */
193  } /* i */
194  } /* j */
195 }
196 } // namespace conrec
#define PRECONDITION(expr, mess)
Definition: Invariant.h:109
Definition: Conrec.h:13
void Contour(const double *d, size_t ilb, size_t iub, size_t jlb, size_t jub, const double *x, const double *y, size_t nc, double *z, std::vector< ConrecSegment > &res)
Definition: Conrec.h:35
ConrecSegment(const RDGeom::Point2D &p1, const RDGeom::Point2D &p2, double isoVal)
Definition: Conrec.h:20
RDGeom::Point2D p2
Definition: Conrec.h:16
RDGeom::Point2D p1
Definition: Conrec.h:15
ConrecSegment(double x1, double y1, double x2, double y2, double isoVal)
Definition: Conrec.h:18