use TetGen's minangle default; add radius_edge_ratio flag

Author: pjaap

CHANGELOG.md

@@ -3,7 +3,8 @@
 ## v2.6.0 June 24, 2025
 
 - Fixed `minangle` parameter forwarding to TetGen
-- New default value `minangle = 10` for `TetGen`, leave default value `20` for `Triangle`
+- New default value `minangle = 0` for `TetGen`, leave default value `20` for `Triangle`
+- New flag `radius_edge_ratio` for `TetGen`
 
 ## v2.5.0 June 24, 2025
 - Allow for Triangulate v3

src/options.jl

@@ -4,26 +4,27 @@ Create dictionary of mesh generation options with default values. These at once
 keyword arguments available to the methods of the package and are listed in the following table:
 
 
-| keyword        | default | 2D  | 3D  | Explanation                                                |
-|:---------------|:-------:|:---:|:---:|:-----------------------------------------------------------|
-| PLC            | true    | -p  | -p  | Triangulate/tetraheralize PLSG/PLC                         |
-| refine         | false   | -r  | -r  | Refines a previously generated mesh.                       |
-| quality        | true    | -q  | -q  | Quality mesh generation                                    |
-| minangle       | 2D: 20  |     |     | Minimum angle for quality                                  |
-|                | 3D: 10  |     |     |                                                            |
-| volumecontrol  | true    | -a  | -a  | Maximum area constraint                                    |
-| maxvolume      | Inf     |     |     | Value of area/volume constraint if less than Inf           |
-| attributes     | true    | -A  | -A  | Regional attribute to each simplex.                        |
-| confdelaunay   | true    | -D  |     | Ensure that all circumcenter lie within the domain.        |
-| nosteiner      | false   | -Y  | -Y  | Prohibits insertion of Steiner points on the mesh boundary |
-| quiet          | true    | -Q  | -Q  | Suppress all output unless an error occurs.                |
-| verbose        | false   | -V  | -V  | Give detailed information.                                 |
-| debugfacets    | true    |     | -d  | Detects self-intersections of facets of the PLC.           |
-| check          | false   | -C  | -C  | Checks the consistency of the final mesh.                  |
-| optlevel       | 1       |     | -O  | Specifies the level of mesh optimization.                  |
-| unsuitable     | nothing |     |     | Unsuitable function                                        |
-| addflags       | ""      |     |     | Additional flags                                           |
-| flags          | nothing |     |     | Set flags, overwrite all other options                     |
+| keyword           | default | 2D  | 3D  | Explanation                                                |
+|:------------------|:-------:|:---:|:---:|:-----------------------------------------------------------|
+| PLC               | true    | -p  | -p  | Triangulate/tetraheralize PLSG/PLC                         |
+| refine            | false   | -r  | -r  | Refines a previously generated mesh.                       |
+| quality           | true    | -q  | -q  | Quality mesh generation                                    |
+| minangle          | 2D: 20  |     |     | Minimum angle for quality                                  |
+|                   | 3D: 0   |     |     |                                                            |
+| radius_edge_ratio | 2.0     |     |     | (3D only) Minimum radius/edge ratio for quality            |
+| volumecontrol     | true    | -a  | -a  | Maximum area constraint                                    |
+| maxvolume         | Inf     |     |     | Value of area/volume constraint if less than Inf           |
+| attributes        | true    | -A  | -A  | Regional attribute to each simplex.                        |
+| confdelaunay      | true    | -D  |     | Ensure that all circumcenter lie within the domain.        |
+| nosteiner         | false   | -Y  | -Y  | Prohibits insertion of Steiner points on the mesh boundary |
+| quiet             | true    | -Q  | -Q  | Suppress all output unless an error occurs.                |
+| verbose           | false   | -V  | -V  | Give detailed information.                                 |
+| debugfacets       | true    |     | -d  | Detects self-intersections of facets of the PLC.           |
+| check             | false   | -C  | -C  | Checks the consistency of the final mesh.                  |
+| optlevel          | 1       |     | -O  | Specifies the level of mesh optimization.                  |
+| unsuitable        | nothing |     |     | Unsuitable function                                        |
+| addflags          | ""      |     |     | Additional flags                                           |
+| flags             | nothing |     |     | Set flags, overwrite all other options                     |
 
 
 For mesh generation, these are turned into mesh generator control flags. This process can be completely
@@ -44,7 +45,8 @@ default_options(mesher) = Dict{Symbol, Any}(
     :PLC => true,
     :refine => false,
     :quality => true,
-    :minangle => mesher == :triangle ? 20 : 10,
+    :minangle => mesher == :triangle ? 20 : 0,
+    :radius_edge_ratio => 2.0,
     :volumecontrol => true,
     :maxvolume => Inf,
     :attributes => true,
@@ -83,12 +85,15 @@ function makeflags(options, mesher)
         options[:PLC] ? flags *= "p" : nothing
         options[:refine] ? flags *= "r" : nothing
         if options[:quality]
+            radius_edge_ratio = Float64(options[:radius_edge_ratio])
             minangle = Float64(options[:minangle])
             if mesher == :tetgen
-                flags *= @sprintf("q/%.2f", minangle)
+                flags *= @sprintf("q%.2f", radius_edge_ratio)
+                flags *= @sprintf("/%.2f", minangle)
             else
                 flags *= @sprintf("q%.2f", minangle)
             end
+
         end
         if options[:volumecontrol]
             flags *= "a"