Fix broken example of simpledemo.lua to work with "simple demo layout"

doc/generic/pgf/CHANGELOG.md

@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Output bounding box adjustment in pgfsys-dvisvgm.def #1275
 - Fix shadings under LuaMetaTeX
 - Resolve missing `gnuplot` plots in manual #1238
+- Fix broken example of simpledemo.lua to work with "very simple demo layout"
 
 ### Changed
 
@@ -40,6 +41,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Yukai Chou (@muzimuzhi)
 - Alexander Grahn
 - Max Chernoff
+- Hanson Char
 
 ## [3.1.10] - 2023-01-13 Henri Menke
 

doc/generic/pgf/pgfmanual-en-gd-algorithm-layer.tex

@@ -139,21 +139,6 @@ \subsubsection{The Hello World of Graph Drawing}
   }
 }
 \end{codeexample}
-\directlua{
-pgf.gd.interface.InterfaceToAlgorithms.declare {
-  key = "very simple demo layout",
-  algorithm = {
-    run =
-      function (self)
-        local alpha = (2 * math.pi) / \luaescapestring{#}self.ugraph.vertices
-        for i,vertex in ipairs(self.ugraph.vertices) do
-          vertex.pos.x = math.cos(i * alpha) * 25
-          vertex.pos.y = math.sin(i * alpha) * 25
-        end
-      end
-  }
-}
-}
 
 This code \emph {declares} a new algorithm (|very simple demo layout|) and
 includes an implementation of the algorithm (through the |run| field of the
@@ -177,15 +162,15 @@ \subsubsection{The Hello World of Graph Drawing}
 the option key |very simple demo layout| becomes available at this point and we
 can use it like this:
 %
-\begin{codeexample}[]
+\begin{codeexample}[preamble={\usetikzlibrary{graphs,graphdrawing} \usegdlibrary{simpledemo}}]
 \tikz [very simple demo layout]
   \graph { f -> c -> e -> a -> {b -> {c, d, f}, e -> b}};
 \end{codeexample}
 
 It turns out, that our little algorithm is already more powerful than one might
 expect. Consider the following example:
 %
-\begin{codeexample}[]
+\begin{codeexample}[preamble={\usetikzlibrary{graphs,graphdrawing} \usegdlibrary{simpledemo}}]
 \tikz [very simple demo layout, componentwise]
   \graph {
     1 -> 2 ->[orient=right] 3 -> 1;
@@ -797,7 +782,7 @@ \subsection{Examples of Implementations of Graph Drawing Algorithms}
 \label{section-gd-examples}
 
 \includeluadocumentationof{pgf.gd.examples.library}
-\includeluadocumentationof{pgf.gd.examples.SimpleDemo}
+\includeluadocumentationof{pgf.gd.examples.simpledemo}
 \includeluadocumentationof{pgf.gd.examples.SimpleEdgeDemo}
 \includeluadocumentationof{pgf.gd.examples.SimpleHuffman}
 

tex/generic/pgf/graphdrawing/lua/pgf/gd/examples/library.lua

@@ -24,7 +24,7 @@ local examples
 
 
 -- Load algorithms from:
-require "pgf.gd.examples.SimpleDemo"
+require "pgf.gd.examples.simpledemo"
 require "pgf.gd.examples.SimpleEdgeDemo"
 require "pgf.gd.examples.SimpleHuffman"
 

tex/generic/pgf/graphdrawing/lua/pgf/gd/examples/SimpleDemo.lua → tex/generic/pgf/graphdrawing/lua/pgf/gd/examples/simpledemo.lua

@@ -23,17 +23,14 @@ local declare = require "pgf.gd.interface.InterfaceToAlgorithms".declare
 ---
 
 declare {
-  key = "simple demo layout",
+  key = "very simple demo layout",
   algorithm = {
     run =
       function (self)
-        local g = self.digraph
-        local alpha = (2 * math.pi) / #g.vertices
-
-        for i,vertex in ipairs(g.vertices) do
-          local radius = vertex.options['radius'] or g.options['radius']
-          vertex.pos.x = radius * math.cos(i * alpha)
-          vertex.pos.y = radius * math.sin(i * alpha)
+        local alpha = (2 * math.pi) / #self.ugraph.vertices
+        for i,vertex in ipairs(self.ugraph.vertices) do
+          vertex.pos.x = math.cos(i * alpha) * 25
+          vertex.pos.y = math.sin(i * alpha) * 25
         end
       end
   },
@@ -49,21 +46,20 @@ declare {
     implement a graph drawing algorithm.
     %
 \begin{codeexample}[code only, tikz syntax=false]
--- File pgf.gd.examples.SimpleDemo
+-- File pgf.gd.examples.simpledemo
 local declare = require "pgf.gd.interface.InterfaceToAlgorithms".declare
 
 declare {
-  key = "simple demo layout",
+  key = "very simple demo layout",
   algorithm = {
     run =
       function (self)
         local g = self.digraph
         local alpha = (2 * math.pi) / #g.vertices
 
         for i,vertex in ipairs(g.vertices) do
-          local radius = vertex.options['radius'] or g.options['radius']
-          vertex.pos.x = radius * math.cos(i * alpha)
-          vertex.pos.y = radius * math.sin(i * alpha)
+          vertex.pos.x = math.cos(i * alpha)
+          vertex.pos.y = math.sin(i * alpha)
         end
       end
   },
@@ -76,7 +72,7 @@ declare {
 
     On the display layer (\tikzname, that is) the algorithm can now
     immediately be employed; you just need to say
-    |\usegdlibrary{examples.SimpleDemo}| at the beginning
+    |\usegdlibrary{simpledemo}| at the beginning
     somewhere.
   "]=]
 }