From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Sat, 23 Jan 2021 04:59:03 +0000 (-0700)
Subject: Improve an error message.
X-Git-Tag: v9.3.0-rc1~576^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F11611%2Fhead;p=dealii.git

Improve an error message.
---

diff --git a/source/grid/grid_out.cc b/source/grid/grid_out.cc
index ed8ac97d70..3d39cc3952 100644
--- a/source/grid/grid_out.cc
+++ b/source/grid/grid_out.cc
@@ -1512,7 +1512,17 @@ void
 GridOut::write_svg(const Triangulation<dim, spacedim> &,
                    std::ostream & /*out*/) const
 {
-  Assert(false, ExcNotImplemented());
+  Assert(false,
+         ExcMessage("Mesh output in SVG format is not implemented for anything "
+                    "other than two-dimensional meshes in two-dimensional "
+                    "space. That's because three-dimensional meshes are best "
+                    "viewed in programs that allow changing the viewpoint, "
+                    "but SVG format does not allow this: It is an inherently "
+                    "2d format, and for three-dimensional meshes would "
+                    "require choosing one, fixed viewpoint."
+                    "\n\n"
+                    "You probably want to output your mesh in a format such "
+                    "as VTK, VTU, or gnuplot."));
 }
 
 
@@ -2787,6 +2797,7 @@ GridOut::write_svg(const Triangulation<2, 2> &tria, std::ostream &out) const
 }
 
 
+
 template <>
 void
 GridOut::write_mathgl(const Triangulation<1> &, std::ostream &) const
@@ -2796,6 +2807,7 @@ GridOut::write_mathgl(const Triangulation<1> &, std::ostream &) const
 }
 
 
+
 template <int dim, int spacedim>
 void
 GridOut::write_mathgl(const Triangulation<dim, spacedim> &tria,