try using LJ sigma for particle radius in VDW mode

tools/lammps-gui/imageviewer.cpp

@@ -132,7 +132,8 @@ static const QString blank(" ");
 
 ImageViewer::ImageViewer(const QString &fileName, LammpsWrapper *_lammps, QWidget *parent) :
     QDialog(parent), menuBar(new QMenuBar), imageLabel(new QLabel), scrollArea(new QScrollArea),
-    lammps(_lammps), group("all"), filename(fileName), useelements(false), usediameter(false)
+    lammps(_lammps), group("all"), filename(fileName), useelements(false), usediameter(false),
+    usesigma(false)
 {
     imageLabel->setBackgroundRole(QPalette::Base);
     imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
@@ -271,7 +272,7 @@ ImageViewer::ImageViewer(const QString &fileName, LammpsWrapper *_lammps, QWidge
     // properties directly since lookup in reset_view() will have failed
     dobox->setChecked(showbox);
     dovdw->setChecked(vdwfactor > 1.0);
-    dovdw->setEnabled(useelements || usediameter);
+    dovdw->setEnabled(useelements || usediameter || usesigma);
     doaxes->setChecked(showaxes);
     dossao->setChecked(usessao);
     doanti->setChecked(antialias);
@@ -458,9 +459,19 @@ void ImageViewer::createImage()
         }
     }
     usediameter = lammps->extract_setting("radius_flag") != 0;
-
+    // use Lennard-Jones sigma for radius, if available
+    usesigma = false;
+    const char *pair_style = (const char *)lammps->extract_global("pair_style");
+    if (!useelements && pair_style && (strncmp(pair_style, "lj/", 3) == 0)) {
+        double **sigma = (double **) lammps->extract_pair("sigma");
+        if (sigma) {
+            usesigma = true;
+            for (int i = 1; i <= ntypes; ++i)
+                adiams += QString("adiam %1 %2 ").arg(i).arg(vdwfactor * sigma[i][i]);
+        }
+    }
     // adjust pushbutton state and clear adiams string to disable VDW display, if needed
-    if (useelements || usediameter) {
+    if (useelements || usediameter || usesigma) {
         auto *button = findChild<QPushButton *>("vdw");
         if (button) button->setEnabled(true);
     } else {
@@ -469,7 +480,7 @@ void ImageViewer::createImage()
         if (button) button->setEnabled(false);
     }
 
-    if (!adiams.isEmpty())
+    if (useelements)
         dumpcmd += blank + "element";
     else
         dumpcmd += blank + settings.value("color", "type").toString();
@@ -503,7 +514,8 @@ void ImageViewer::createImage()
 
     dumpcmd += " modify boxcolor " + settings.value("boxcolor", "yellow").toString();
     dumpcmd += " backcolor " + settings.value("background", "black").toString();
-    if (!adiams.isEmpty()) dumpcmd += blank + elements + blank + adiams + blank;
+    if (useelements) dumpcmd += blank + elements + blank + adiams + blank;
+    if (usesigma) dumpcmd += blank + adiams + blank;
     settings.endGroup();
 
     lammps->command(dumpcmd.toLocal8Bit());

tools/lammps-gui/imageviewer.h

@@ -88,7 +88,7 @@ private:
     int xsize, ysize;
     int hrot, vrot;
     double zoom, vdwfactor;
-    bool showbox, showaxes, antialias, usessao, useelements, usediameter;
+    bool showbox, showaxes, antialias, usessao, useelements, usediameter, usesigma;
 };
 #endif
 

tools/lammps-gui/lammpswrapper.cpp

@@ -76,6 +76,19 @@ void *LammpsWrapper::extract_global(const char *keyword)
     return val;
 }
 
+void *LammpsWrapper::extract_pair(const char *keyword)
+{
+    void *val = nullptr;
+    if (lammps_handle) {
+#if defined(LAMMPS_GUI_USE_PLUGIN)
+        val = ((liblammpsplugin_t *)plugin_handle)->extract_pair(lammps_handle, keyword);
+#else
+        val = lammps_extract_pair(lammps_handle, keyword);
+#endif
+    }
+    return val;
+}
+
 void *LammpsWrapper::extract_atom(const char *keyword)
 {
     void *val = nullptr;

tools/lammps-gui/lammpswrapper.h

@@ -32,6 +32,7 @@ public:
     int version();
     int extract_setting(const char *keyword);
     void *extract_global(const char *keyword);
+    void *extract_pair(const char *keyword);
     void *extract_atom(const char *keyword);
 
     int id_count(const char *idtype);