git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@11608 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/MISC/fix_oneway.cpp

@@ -0,0 +1,109 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+/* ----------------------------------------------------------------------
+   Contributing author: Axel Kohlmeyer (ICTP, Italy)
+------------------------------------------------------------------------- */
+
+#include "string.h"
+#include "fix_oneway.h"
+#include "atom.h"
+#include "domain.h"
+#include "error.h"
+#include "force.h"
+#include "region.h"
+
+using namespace LAMMPS_NS;
+using namespace FixConst;
+
+enum{NONE=-1,X=0,Y=1,Z=2,XYZMASK=3,MINUS=4,PLUS=0};
+
+/* ---------------------------------------------------------------------- */
+
+FixOneWay::FixOneWay(LAMMPS *lmp, int narg, char **arg) : Fix(lmp, narg, arg)
+{
+  direction = NONE;
+  regionidx = 0;
+  regionstr = NULL;
+
+  if (narg < 6) error->all(FLERR,"Illegal fix oneway command");
+
+  nevery = force->inumeric(FLERR,arg[3]);
+  if (nevery < 1) error->all(FLERR,"Illegal nevery value for fix oneway");
+
+  int len = strlen(arg[4]);
+  regionstr = new char[len];
+  strcpy(regionstr,arg[4]);
+
+  if (strcmp(arg[5], "x") == 0) direction = X|PLUS;
+  if (strcmp(arg[5], "X") == 0) direction = X|PLUS;
+  if (strcmp(arg[5], "y") == 0) direction = Y|PLUS;
+  if (strcmp(arg[5], "Y") == 0) direction = Y|PLUS;
+  if (strcmp(arg[5], "z") == 0) direction = Z|PLUS;
+  if (strcmp(arg[5], "Z") == 0) direction = Z|PLUS;
+  if (strcmp(arg[5],"-x") == 0) direction = X|MINUS;
+  if (strcmp(arg[5],"-X") == 0) direction = X|MINUS;
+  if (strcmp(arg[5],"-y") == 0) direction = Y|MINUS;
+  if (strcmp(arg[5],"-Y") == 0) direction = Y|MINUS;
+  if (strcmp(arg[5],"-z") == 0) direction = Z|MINUS;
+  if (strcmp(arg[5],"-Z") == 0) direction = Z|MINUS;
+
+  global_freq = nevery;
+}
+
+/* ---------------------------------------------------------------------- */
+
+FixOneWay::~FixOneWay()
+{
+  if (regionstr) delete[] regionstr;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixOneWay::setmask()
+{
+  return END_OF_STEP;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixOneWay::init()
+{
+  regionidx = domain->find_region(regionstr);
+  if (regionidx < 0)
+    error->warning(FLERR,"Region for fix oneway does not exist");
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixOneWay::end_of_step()
+{
+  Region *region = domain->regions[regionidx];
+  const int idx = direction & XYZMASK;
+
+  const double * const * const x = atom->x;
+  double * const * const v = atom->v;
+  const int *mask = atom->mask;
+  const int nlocal = atom->nlocal;
+
+  for (int i = 0; i < nlocal; ++i) {
+    if ((mask[i] & groupbit) && region->match(x[i][0],x[i][1],x[i][2])) {
+      if (direction & MINUS) {
+        if (v[i][idx] > 0.0) v[i][idx] = -v[i][idx];
+      } else {
+        if (v[i][idx] < 0.0) v[i][idx] = -v[i][idx];
+      }
+    }
+  }
+}
+

src/MISC/fix_oneway.h

@@ -0,0 +1,54 @@
+/* -*- c++ -*- ----------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#ifdef FIX_CLASS
+
+FixStyle(oneway,FixOneWay)
+
+#else
+
+#ifndef LMP_FIX_ONEWAY_H
+#define LMP_FIX_ONEWAY_H
+
+#include "fix.h"
+
+namespace LAMMPS_NS {
+
+class FixOneWay : public Fix {
+ public:
+  FixOneWay(class LAMMPS *, int, char **);
+  virtual ~FixOneWay();
+  int setmask();
+  virtual void init();
+  virtual void end_of_step();
+
+ protected:
+  int direction;
+  int regionidx;
+  char *regionstr;
+};
+
+}
+
+#endif
+#endif
+
+/* ERROR/WARNING messages:
+
+E: Illegal ... command
+
+Self-explanatory.  Check the input script syntax and compare to the
+documentation for the command.  You can use -echo screen as a
+command-line option when running LAMMPS to see the offending line.
+
+*/