Only provide a single Lua function for creating debug axes

modules/debugging/scripts/axes.lua

@@ -1,35 +1,47 @@
 openspace.debugging.documentation = {
   {
     Name = "createCoordinateAxes",
-    Arguments = {},
+    Arguments = {
+      { "nodeIdentifier", "String?" },
+      { "scale", "Number?" }
+    },
     Documentation = [[
       Creates a new scene graph node that show the coordinate system used for the
-      currently selected focus node.
+      currently selected focus node. The first argument specifies the name of the
+      scene graph node for which the axes should be added. If this parameter is
+      not specified, the current focus node is used instead. The second argument
+      provides the length of the coordinate axis in meters. If this value is not
+      specified 2.5 times the interaction sphere of the selected node is used
+      instead.
     ]]
   }
 }
 
-openspace.debugging.createCoordinateAxes = function ()
-  local anchor = openspace.navigation.getNavigationState().Anchor
-  local radius = openspace.propertyValue("Scene." .. anchor .. ".EvaluatedInteractionSphere")
+openspace.debugging.createCoordinateAxes = function (nodeIdentifier, scale)
+  local node = nodeIdentifier or openspace.navigation.getNavigationState().Anchor
+  local sphere = openspace.propertyValue("Scene." .. node .. ".EvaluatedInteractionSphere")
+  if sphere == -1 then
+    sphere = 1
+  end
+  local size = scale or sphere * 2.5
 
-  local node = {
-    Identifier = anchor .. "_DebugAxes",
-    Parent = anchor,
+  local nodespec = {
+    Identifier = node .. "_DebugAxes",
+    Parent = node,
     Transform = {
       Scale = {
         Type = "StaticScale",
-        Scale = radius * 2.5
+        Scale = size
       }
     },
     Renderable = {
       Type = "RenderableCartesianAxes"
     },
     GUI = {
-      Name = anchor .. " (Debug Axes)",
-      Path = openspace.propertyValue("Scene." .. anchor .. ".GuiPath")
+      Name = node .. " (Debug Axes)",
+      Path = openspace.propertyValue("Scene." .. node .. ".GuiPath")
     }
   }
 
-  openspace.addSceneGraphNode(node)
+  openspace.addSceneGraphNode(nodespec)
 end