minor tweaks simplify algorithm

doc/src/Tools.rst

@@ -1023,17 +1023,18 @@ For more details please see the README.md file in that folder.
 stl_bin2txt tool
 ----------------
 
-The file stl_bin2txt.cpp converts binary STL files - like they are frequently
+The file stl_bin2txt.cpp converts binary STL files - like they are
-offered for download on the web - into ASCII format STL files that LAMMPS
+frequently offered for download on the web - into ASCII format STL files
-can read with the :doc:`create_atoms mesh <create_atoms>` or the
+that LAMMPS can read with the :doc:`create_atoms mesh <create_atoms>` or
-:doc:`fix smd/wall_surface` commands.  The syntax for running the tool is
+the :doc:`fix smd/wall_surface <fix_smd_wall_surface>` commands.  The syntax
+for running the tool is
 
 .. code-block:: bash
 
    stl_bin2txt infile.stl outfile.stl
 
 which creates outfile.stl from infile.stl.  This tool must be compiled
-on a platform compatible with the byteordering that was used to create
+on a platform compatible with the byte-ordering that was used to create
 the binary file.  This usually is a so-called little endian hardware
 (like x86).
 

doc/src/create_atoms.rst

@@ -21,7 +21,7 @@ Syntax
        *single* args = x y z
          x,y,z = coordinates of a single particle (distance units)
        *mesh* args = STL-file
-         STL-file = file with triangle mesh in STL format
+         STL-file = file with triangle mesh in ASCII STL format
        *random* args = N seed region-ID
          N = number of particles to create
          seed = random # seed (positive integer)
@@ -73,7 +73,7 @@ Examples
    create_atoms 3 single 0 0 5
    create_atoms 1 box var v set x xpos set y ypos
    create_atoms 2 random 50 12345 NULL overlap 2.0 maxtry 50
-   create_atoms 1 mesh funnel.stl units box radiusscale 1.5
+   create_atoms 1 mesh funnel.stl units box radiusscale 1.1
 
 Description
 """""""""""
@@ -86,7 +86,7 @@ alternative to reading in atom coordinates explicitly via a
 command.  A simulation box must already exist, which is typically
 created via the :doc:`create_box <create_box>` command.  Before using
 this command, a lattice must also be defined using the :doc:`lattice
-<lattice>` command, unless you specify the *single* or *mesh* style with
+<lattice>` command, unless you specify the *single* style with
 units = box or the *random* style.  For the remainder of this doc page,
 a created atom or molecule is referred to as a "particle".
 
@@ -124,12 +124,20 @@ the specified coordinates.  This can be useful for debugging purposes
 or to create a tiny system with a handful of particles at specified
 positions.
 
-For the *mesh* style, a file with a triangle mesh in `STL format
+For the *mesh* style, a file with a triangle mesh in `ASCII STL format
 <https://en.wikipedia.org/wiki/STL_(file_format)#ASCII_STL>`_ is read
-and a particle is placed into the center of each triangle.  If the atom
+and one or more particles are placed into the area of each triangle.
-style in use allows to set a per-atom radius this radius is set to the
+Binary STL files (e.g. as frequently offered for 3d-printing) can be
-largest distance of any of the triangle vertices from its center.  The
+converted to ASCII with the :ref:`stl_bin2txt tool <stlconvert>`.  The
-radius can be adjusted with the *radiussscale* option.
+use of the *units box* option is required and also a :doc:`lattice
+<lattice>` must be defined.  A particle is created at the center of the
+triangle unless the average distance of the triangle vertices from its
+center is larger than the lattice spacing in x direction.  In that case
+the triangle is split into two halves along the its longest side and
+each of those two triangles considered for particle insertion.  If the
+atom style in use allows to set a per-atom radius this radius is set to
+the average distance of the triangle vertices from its center times the
+value of the *radiussscale* keyword (default: 1.0).
 
 For the *random* style, *N* particles are added to the system at
 randomly generated coordinates, which can be useful for generating an

doc/utils/sphinx-config/false_positives.txt

@@ -3216,6 +3216,7 @@ Stesmans
 stiffnesses
 Stillinger
 stk
+stl
 stochastically
 stochasticity
 Stockmayer

src/create_atoms.cpp

@@ -41,12 +41,14 @@
 #include <cstring>
 
 using namespace LAMMPS_NS;
-using namespace MathConst;
+using MathConst::MY_2PI;
+using MathConst::MY_PI;
+using MathConst::THIRD;
 
-#define BIG 1.0e30
+static constexpr double BIG = 1.0e30;
-#define EPSILON 1.0e-6
+static constexpr double EPSILON = 1.0e-6;
-#define LB_FACTOR 1.1
+static constexpr double LB_FACTOR = 1.1;
-#define DEFAULT_MAXTRY 1000
+static constexpr int DEFAULT_MAXTRY = 1000;
 
 enum { BOX, REGION, SINGLE, RANDOM, MESH };
 enum { ATOM, MOLECULE };
@@ -846,26 +848,21 @@ int CreateAtoms::add_tricenter(const double vert[3][3], tagint molid, double rad
 
   MathExtra::add3(vert[0], vert[1], center);
   MathExtra::add3(center, vert[2], temp);
-  MathExtra::scale3(1.0 / 3.0, temp, center);
+  MathExtra::scale3(THIRD, temp, center);
 
   MathExtra::sub3(center, vert[0], temp);
-  const double r1 = MathExtra::len3(temp);
+  double ravg = MathExtra::len3(temp);
   MathExtra::sub3(center, vert[1], temp);
-  const double r2 = MathExtra::len3(temp);
+  ravg += MathExtra::len3(temp);
   MathExtra::sub3(center, vert[2], temp);
-  const double r3 = MathExtra::len3(temp);
+  ravg += MathExtra::len3(temp);
-  const double rmin = MIN(MIN(r1, r2), r3);
+  ravg *= THIRD;
-  const double rmax = MAX(MAX(r1, r2), r3);
-  const double ravg = 1.0 / 3.0 * (r1 + r2 + r3);
 
-  // if the triangle is too large, split it in half along the longest side and recurse
+  // if the average distance of the vertices from the center is larger than the
-  //
+  // lattice parameter, the triangle is split it in half along its longest side
-  // the triangle is considered too large if either the shortest vertex distance from the
-  // center is larger than lattice parameter or the ratio between longest and shortest is
-  // larger than 2.0 *and* the longest distance from the center is larger than lattice parameter
 
   int ilocal = 0;
-  if ((rmin >= xlat) || ((rmax / rmin >= 1.5) && (rmax >= xlat))) {
+  if (ravg > xlat) {
     double vert1[3][3], vert2[3][3], side[3][3];
 
     // determine side vectors and longest side