move fsaa keyword next to ssao and away from dump_modify

we don't need to reallocate the buffers this way

doc/src/dump_image.rst

@@ -24,7 +24,7 @@ Syntax
 * color = atom attribute that determines color of each atom
 * diameter = atom attribute that determines size of each atom
 * zero or more keyword/value pairs may be appended
-* keyword = *atom* or *adiam* or *bond* or *grid* or *line* or *tri* or *body* or *fix* or *size* or *view* or *center* or *up* or *zoom* or *box* or *axes* or *subbox* or *shiny* or *ssao*
+* keyword = *atom* or *adiam* or *bond* or *grid* or *line* or *tri* or *body* or *fix* or *size* or *view* or *center* or *up* or *zoom* or *box* or *axes* or *subbox* or *shiny* or *fsaa* or *ssao*
 
   .. parsed-literal::
 
@@ -85,6 +85,8 @@ Syntax
          diam = diameter of subdomain lines as fraction of shortest box length
        *shiny* value = sfactor = shinyness of spheres and cylinders
          sfactor = shinyness of spheres and cylinders from 0.0 to 1.0
+       *fsaa* arg = yes/no
+         yes/no = do or do not apply anti-aliasing
        *ssao* value = shading seed dfactor = SSAO depth shading
          shading = *yes* or *no* = turn depth shading on/off
          seed = random # seed (positive integer)
@@ -103,7 +105,7 @@ Syntax
    dump_modify dump-ID keyword values ...
 
 * these keywords apply only to the *image* and *movie* styles and are documented on this page
-* keyword = *acolor* or *adiam* or *amap* or *gmap* or *backcolor* or *bcolor* or *bdiam* or *bitrate* or *boxcolor* or *color* or *framerate* or *fsaa* or *gmap*
+* keyword = *acolor* or *adiam* or *amap* or *gmap* or *backcolor* or *bcolor* or *bdiam* or *bitrate* or *boxcolor* or *color* or *framerate* or *gmap*
 * see the :doc:`dump modify <dump_modify>` doc page for more general keywords
 
   .. parsed-literal::
@@ -151,8 +153,6 @@ Syntax
          R,G,B = red/green/blue numeric values from 0.0 to 1.0
        *framerate* arg = fps
          fps = frames per second for movie
-       *fsaa* arg = yes/no
-         yes/no = do or do not apply anti-aliasing
        *gmap* args = identical to *amap* args
 
 Examples
@@ -229,7 +229,7 @@ details have to be looked up in the `FFmpeg documentation
 described below.
 
 To write out JPEG and PNG format files, you must build LAMMPS with
-support for the corresponding JPEG or PNG library. To convert images
+support for the corresponding JPEG or PNG library.  To convert images
 into movies, LAMMPS has to be compiled with the -DLAMMPS_FFMPEG
 flag. See the :doc:`Build settings <Build_settings>` page for
 details.
@@ -599,13 +599,25 @@ image will appear.  The *sfactor* value must be a value 0.0 <=
 *sfactor* <= 1.0, where *sfactor* = 1 is a highly reflective surface
 and *sfactor* = 0 is a rough non-shiny surface.
 
-The *ssao* keyword turns on/off a screen space ambient occlusion
-(SSAO) model for depth shading.  If *yes* is set, then atoms further
-away from the viewer are darkened via a randomized process, which is
-perceived as depth.  The calculation of this effect can increase the
-cost of computing the image by roughly 2x.  The strength of the effect
-can be scaled by the *dfactor* parameter.  If *no* is set, no depth
-shading is performed.
+.. versionadded:: TBD
+
+The *fsaa* keyword can be used with the dump image command to improve
+the image quality by enabling full scene anti-aliasing.  Internally the
+image is rendered at twice the width and height and then scaled down by
+computing the average of each 2x2 block of pixels to produce a single
+pixel in the final image at the original size. This produces images with
+smoother, less ragged edges.  The application of this algorithm can
+increase the cost of computing the image by about 3x or more.
+
+The *ssao* keyword turns on/off a screen space ambient occlusion (SSAO)
+model for depth shading.  If *yes* is set, then atoms further away from
+the viewer are darkened via a randomized process, which is perceived as
+depth.  The strength of the effect can be scaled by the *dfactor*
+parameter.  If *no* is set, no depth shading is performed.  The
+calculation of this effect can increase the cost of computing the image
+substantially by 5x or more, especially with larger images.  When used
+in combination with the *fsaa* keyword the computational cost of depth
+shading is particularly large.
 
 ----------
 
@@ -959,20 +971,6 @@ frequently.
 
 ----------
 
-.. versionadded:: TBD
-
-The *fsaa* keyword can be used with the dump image command to improve
-the image quality by enabling full scene anti-aliasing.  Internally the
-image is rendered at twice the width and height and then scaled down by
-computing the average of each 2x2 block of pixels to produce a single
-pixel in the final image at the original size. This produces images with
-smoother, less ragged edges.  The calculation of this effect can
-increase the cost of computing the image by roughly 4x or more,
-especially for large images and with large processor counts due to
-increased communication cost.
-
-----------
-
 The *gmap* keyword can be used with the dump image command, with its
 *grid* keyword, to setup a color map.  The color map is used to assign
 a specific RGB (red/green/blue) color value to an individual grid cell
@@ -1067,6 +1065,7 @@ The defaults for the dump_modify keywords specific to dump image and dump movie
 * boxcolor = yellow
 * color = 140 color names are pre-defined as listed below
 * framerate = 24
+* fsaa = no
 * gmap = min max cf 0.0 2 min blue max red
 
 ----------

doc/utils/sphinx-config/false_positives.txt

@@ -1195,6 +1195,7 @@ Freitas
 Frenkel
 Friedrichs
 fs
+fsaa
 fsh
 fstyle
 fsw

src/dump_image.cpp

@@ -248,10 +248,14 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
       if (iarg+3 > narg) error->all(FLERR,"Illegal dump image command");
       int width = utils::inumeric(FLERR,arg[iarg+1],false,lmp);
       int height = utils::inumeric(FLERR,arg[iarg+2],false,lmp);
-      if (width <= 0 || height <= 0)
-        error->all(FLERR,"Illegal dump image command");
-      image->width = width;
-      image->height = height;
+      if (width <= 0 || height <= 0) error->all(FLERR,"Illegal dump image command");
+      if (image->fsaa) {
+        image->width = width*2;
+        image->height = height*2;
+      } else {
+        image->width = width;
+        image->height = height;
+      }
       iarg += 3;
 
     } else if (strcmp(arg[iarg],"view") == 0) {
@@ -345,6 +349,23 @@ DumpImage::DumpImage(LAMMPS *lmp, int narg, char **arg) :
       image->shiny = shiny;
       iarg += 2;
 
+    } else if (strcmp(arg[iarg],"fsaa") == 0) {
+      if (iarg+2 > narg) error->all(FLERR,"Illegal dump_modify command");
+      int aa = utils::logical(FLERR, arg[iarg+1], false, lmp);
+      if (aa) {
+        if (!image->fsaa) {
+          image->width = image->width*2;
+          image->height = image->height*2;
+        }
+      } else {
+        if (image->fsaa) {
+          image->width = image->width/2;
+          image->height = image->height/2;
+        }
+      }
+      image->fsaa = aa;
+      iarg += 2;
+
     } else if (strcmp(arg[iarg],"ssao") == 0) {
       if (iarg+4 > narg) error->all(FLERR,"Illegal dump image command");
       image->ssao = utils::logical(FLERR,arg[iarg+1],false,lmp);
@@ -1555,35 +1576,6 @@ int DumpImage::modify_param(int narg, char **arg)
     return n;
   }
 
-  // if antialias state changes, we need to increase the buffer space
-  // change the (internal) image dimensions and reset the view parameters
-  if (strcmp(arg[0],"fsaa") == 0) {
-    if (narg < 2) error->all(FLERR,"Illegal dump_modify command");
-    int aa = utils::logical(FLERR, arg[1], false, lmp);
-    if (image->fsaa == NO) {
-      if (aa == YES) {
-        image->width = image->width*2;
-        image->height = image->height*2;
-        // reallocate buffers to make room
-        image->buffers();
-      }
-    } else {
-      if (aa == NO) {
-        image->width = image->width/2;
-        image->height = image->height/2;
-        box_bounds();
-        box_center();
-        view_params();
-      }
-    }
-    image->fsaa = aa;
-    // reset size based parameters
-    box_bounds();
-    box_center();
-    view_params();
-    return 2;
-  }
-
   if (strcmp(arg[0],"bcolor") == 0) {
     if (narg < 3) error->all(FLERR,"Illegal dump_modify command");
     if (atom->nbondtypes == 0)