1 // ******************************************************************************
2 //
3 // Title: Force Field X.
4 // Description: Force Field X - Software for Molecular Biophysics.
5 // Copyright: Copyright (c) Michael J. Schnieders 2001-2025.
6 //
7 // This file is part of Force Field X.
8 //
9 // Force Field X is free software; you can redistribute it and/or modify it
10 // under the terms of the GNU General Public License version 3 as published by
11 // the Free Software Foundation.
12 //
13 // Force Field X is distributed in the hope that it will be useful, but WITHOUT
14 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
15 // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 // details.
17 //
18 // You should have received a copy of the GNU General Public License along with
19 // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
20 // Place, Suite 330, Boston, MA 02111-1307 USA
21 //
22 // Linking this library statically or dynamically with other modules is making a
23 // combined work based on this library. Thus, the terms and conditions of the
24 // GNU General Public License cover the whole combination.
25 //
26 // As a special exception, the copyright holders of this library give you
27 // permission to link this library with independent modules to produce an
28 // executable, regardless of the license terms of these independent modules, and
29 // to copy and distribute the resulting executable under terms of your choice,
30 // provided that you also meet, for each linked independent module, the terms
31 // and conditions of the license of that module. An independent module is a
32 // module which is not derived from or based on this library. If you modify this
33 // library, you may extend this exception to your version of the library, but
34 // you are not obligated to do so. If you do not wish to do so, delete this
35 // exception statement from your version.
36 //
37 // ******************************************************************************
38 package ffx.openmm;
39
40 import static edu.uiowa.jopenmm.OpenMMLibrary.OpenMM_TwoParticleAverageSite_create;
41 import static edu.uiowa.jopenmm.OpenMMLibrary.OpenMM_TwoParticleAverageSite_destroy;
42 import static edu.uiowa.jopenmm.OpenMMLibrary.OpenMM_TwoParticleAverageSite_getWeight;
43
44 /**
45 * This is a VirtualSite that computes the particle location as a weighted average
46 * of two other particle's locations. This means the virtual site is on the
47 * line passing through the two particles.
48 */
49 public class TwoParticleAverageSite extends VirtualSite {
50
51 /**
52 * Create a new TwoParticleAverageSite virtual site. Normally weight1 and weight2
53 * should add up to 1, although this is not strictly required.
54 *
55 * @param particle1 the index of the first particle
56 * @param particle2 the index of the second particle
57 * @param weight1 the weight factor (typically between 0 and 1) for the first particle
58 * @param weight2 the weight factor (typically between 0 and 1) for the second particle
59 */
60 public TwoParticleAverageSite(int particle1, int particle2, double weight1, double weight2) {
61 super(OpenMM_TwoParticleAverageSite_create(particle1, particle2, weight1, weight2));
62 }
63
64 /**
65 * Destroy the virtual site.
66 */
67 @Override
68 public void destroy() {
69 if (pointer != null) {
70 OpenMM_TwoParticleAverageSite_destroy(pointer);
71 pointer = null;
72 }
73 }
74
75 /**
76 * Get the weight factor used for a particle this virtual site depends on.
77 *
78 * @param particle the particle to get (between 0 and getNumParticles())
79 * @return the weight factor used for that particle
80 */
81 public double getWeight(int particle) {
82 return OpenMM_TwoParticleAverageSite_getWeight(pointer, particle);
83 }
84 }