fix links

docs/modules/core/pages/material/material_definitions.adoc

@@ -77,7 +77,7 @@ myGeometryMesh.scaleTextureCoordinates(new Vector2f(2f, 2f));
 ----
 
 
-For details see also: xref:tutorials:concepts/how_to_use_materials.adoc[How to Use Materials]
+For details see also: xref:material/how_to_use_materials.adoc[How to Use Materials]
 
 
 === Examples

docs/modules/core/pages/material/materials_overview.adoc

@@ -12,7 +12,7 @@ In jMonkeyEngine 3, colors and textures are represented as Material objects.
 
 [TIP]
 ====
-Find out quickly xref:tutorials:concepts/how_to_use_materials.adoc[How to Use Materials], including the most commonly used code samples and RenderStates. +
+Find out quickly xref:material/how_to_use_materials.adoc[How to Use Materials], including the most commonly used code samples and RenderStates. +
 Or find more background info on xref:jme3/advanced/material_definitions.adoc[How to use Material Definitions].
 ====
 

docs/modules/core/pages/scene/mesh.adoc

@@ -22,7 +22,7 @@ All visible game elements in a scene, whether it is a Model or a Shape, are made
 You have several options when xref:scene/spatial.adoc[creating Geometries from meshes]:
 
 *  Use built-in <<jme3/advanced/shape#,Shape>>s as meshes;
-*  Load <<jme3/advanced/3d_models#,3D models>> (that is, meshes created in external applications); or
+*  Load xref:scene/3d_models.adoc[3D models] (that is, meshes created in external applications); or
 *  Create free-form xref:scene/custom_meshes.adoc[custom meshes] programmatically.
 
 

docs/modules/networking/pages/headless_server.adoc

@@ -52,9 +52,9 @@ public static void main(String[] args) {
 
 == Next steps
 
-Okay, so you can now start your game in a headless 'server mode', where to go from here?
+Okay, so you can now start your game in a headless "`server mode`", where to go from here?
 
 *  Parse `String[] args` from the `main`-method to enable server mode on demand (e.g. start your server like `java -jar mygame.jar –server`.
 *  Integrate xref:networking.adoc.adoc[SpiderMonkey], to provide game updates to the server over a network.
 *  Only execute code that's needed. (E.g. place all rendering code inside an `if (servermode)`-block) (or `if (!servermode)` for the client).
-*  Add decent <<jme3/advanced/logging#,logging>> so your server actually makes sense.
+*  Add decent xref:tutorials:how-to/java/logging.adoc[logging] so your server actually makes sense.

docs/modules/networking/pages/networking.adoc

@@ -530,7 +530,7 @@ Multithreading means that you create a Callable. A Callable is a Java class repr
 app.enqueue(callable);
 ----
 
-Learn more about using <<jme3/advanced/multithreading#,multithreading>> in jME3 here.
+Learn more about using xref:core:app/multithreading.adoc[multithreading] in jME3 here.
 
 For general advice, see the articles link:https://developer.valvesoftware.com/wiki/Source_Multiplayer_Networking[MultiPlayer Networking] and link:https://developer.valvesoftware.com/wiki/Latency_Compensating_Methods_in_Client/Server_In-game_Protocol_Design_and_Optimization[Latency Compensating Methods in Client/Server In-game Protocol Design and Optimization] by the Valve Developer Community.
 

docs/modules/tutorials/pages/beginner/hello_material.adoc

@@ -396,7 +396,7 @@ You have also learned that a material can be stored in a .j3m file. The file ref
 
 *See also:*
 
-*  xref:tutorials:concepts/how_to_use_materials.adoc[How to Use Materials]
+*  xref:core:material/how_to_use_materials.adoc[How to Use Materials]
 *  xref:sdk:material_editing.adoc[Material Editing]
 *  link:https://hub.jmonkeyengine.org/t/jmonkeyengine3-material-system-full-explanation/12947[Materials] forum thread
 //*  link:http://nbviewer.jupyter.org/github/jMonkeyEngine/wiki/blob/master/src/docs/resources/tutorials/material/jME3_materials.pdf[jME3 Materials documentation (PDF)]

docs/modules/tutorials/pages/concepts/best_practices.adoc

@@ -261,7 +261,7 @@ Read all about xref:core:scene/control/custom_controls.adoc[Custom Controls] and
 === Optimize Application Performance
 
 *  xref:concepts/optimization.adoc[Optimization] – How to avoid wasting cycles
-*  xref:ROOT:jme3/advanced/multithreading.adoc[Multithreading] – Use concurrency for long-running background tasks, but don't manipulate the scene graph from outside the main thread (update loop)!
+*  xref:core:app/multithreading.adoc[Multithreading] – Use concurrency for long-running background tasks, but don't manipulate the scene graph from outside the main thread (update loop)!
 *  You can add a xref:sdk:debugging_profiling_testing.adoc[Java Profiler] to the jMonkeyEngine SDK via Tools → Plugins → Available. The profiler presents statistics on the lifecycle of methods and objects. Performance problems may be caused by just a few methods that take long, or are called too often (try to cache values to avoid this). If object creation and garbage collection counts keep increasing, you are looking at a memory leak.
 
 
@@ -289,7 +289,7 @@ Treat javadoc as messages to your future self. `genNextVal() generates the next
 
 *A xref:sdk:debugging_profiling_testing.adoc[Java Debugger]* is included in the jMonkeyEngine SDK. It allows you to set a break point in your code near the line of code where an exception happens. Then you step through the execution line by line and watch object and variable states live, to detect where the bug starts.
 
-*Use the xref:ROOT:jme3/advanced/logging.adoc[Logger]* to print status messages during the development and debugging phase, instead of System.out.println(). The logger can be switched off with one line of code, whereas commenting out all your `println()`s takes a while.
+*Use the xref:how-to/java/logging.adoc[Logger]* to print status messages during the development and debugging phase, instead of System.out.println(). The logger can be switched off with one line of code, whereas commenting out all your `println()`s takes a while.
 
 *Unit Testing (link:https://docs.oracle.com/javase/1.5.0/docs/guide/language/assert.html[Java Assertions])* has a different status in 3D graphics development than in other types of software. You cannot write assertions that automatically test whether the rendered image _looks_ correct, or whether interactions are _intuitive_. Still you should xref:sdk:debugging_profiling_testing.adoc[create simple test cases] for individual game features such as loaders, content generators, effects. Run the test cases now and then to see whether they still work as intended – or whether they are suffering from regressions or side-effects. Keep the test classes in the `test` directory of your project, don't include them in the distribution.
 
@@ -307,7 +307,7 @@ Treat javadoc as messages to your future self. `genNextVal() generates the next
 *  Verify that all assets are up-to-date and converted to .j3o.
 *  Verify that your code loads the optimized .j3o files, and not the original model formats.
 *  Prepare licenses of assets that you use for inclusion. (You _did_ obtain permission to use them, right…?)
-*  Switch off fine xref:ROOT:jme3/advanced/logging.adoc[logging] output.
+*  Switch off fine xref:how-to/java/logging.adoc[logging] output.
 *  Prepare promotional art: The most awesome screenshots (in thumbnail, square, vertical, horizontal, and fullscreen formats) and video clips. Include name, contact info, slogan, etc., so future customers can find you.
 *  Prepare a readme.txt file, or installation guide, or handbook – if applicable.
 *  Get a certificate if one is required for your distribution method (see below).

docs/modules/tutorials/pages/concepts/faq.adoc

@@ -28,12 +28,12 @@ viewPort.setBackgroundColor(ColorRGBA.Blue);
 
 === Can I customize the SimpleApplication class?
 
-Yes! Actually, you MUST customize it! For your own games, you always create a custom base class that extends link:https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-core/src/main/java/com/jme3/app/SimpleApplication.java[com.jme3.app.SimpleApplication] class. From now on it's no longer a `simple application` – it's now your game. Configure your xref:ROOT:jme3/intermediate/appsettings.adoc[application settings], implement methods, and customize away!
+Yes! Actually, you MUST customize it! For your own games, you always create a custom base class that extends link:https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-core/src/main/java/com/jme3/app/SimpleApplication.java[com.jme3.app.SimpleApplication] class. From now on it's no longer a `simple application` – it's now your game. Configure your xref:core:system/appsettings.adoc[application settings], implement methods, and customize away!
 
 *Learn more:*
 
 * xref:core:app/simpleapplication.adoc[SimpleApplication]
-* xref:ROOT:jme3/intermediate/appsettings.adoc[AppSettings]
+* xref:core:system/appsettings.adoc[AppSettings]
 
 
 === How can I switch between screens or states?
@@ -72,7 +72,7 @@ java.util.logging.Logger.getLogger("").setLevel(Level.SEVERE);
 
 *Learn more:*
 
-* xref:ROOT:jme3/advanced/logging.adoc[Logging]
+* xref:how-to/java/logging.adoc[Logging]
 
 
 === Why does the executable crash with "Cannot locate resource"?
@@ -160,7 +160,7 @@ You create sounds in an audio editor, for example, Audacity, and export them as
 
 *Learn more:*
 
-* xref:ROOT:jme3/advanced/3d_models.adoc[3D Models]
+* xref:core:scene/3d_models.adoc[3D Models]
 * xref:concepts/multi-media_asset_pipeline.adoc[multi-media asset pipeline]
 * xref:how-to/modeling/blender/blender.adoc[Creating assets in Blender3D]
 * link:https://www.blender.org[Download Blender]
@@ -304,7 +304,7 @@ Use the AssetManager to load Materials, and change material settings.
 *Learn more:*
 
 * xref:beginner/hello_material.adoc[Hello Material]
-* xref:concepts/how_to_use_materials.adoc[How To Use Materials]
+* xref:core:material/how_to_use_materials.adoc[How To Use Materials]
 * xref:core:material/materials_overview.adoc[Materials Overview], xref:core:asset/asset_manager.adoc[Asset Manager]
 
 *Code sample:*
@@ -320,7 +320,7 @@ Create Textures as image files. Use the AssetManager to load a Material and use
 *Learn more:*
 
 * xref:beginner/hello_material.adoc[Hello Material]
-* xref:concepts/how_to_use_materials.adoc[How To Use Materials]
+* xref:core:material/how_to_use_materials.adoc[How To Use Materials]
 * xref:core:material/materials_overview.adoc[Materials Overview]
 * xref:core:asset/asset_manager.adoc[Asset Manager]
 * link:https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-core/src/main/java/com/jme3/asset/AssetManager.java[com.jme3.assets.AssetManager]
@@ -362,7 +362,7 @@ material.getAdditionalRenderState().setBlendMode(BlendMode.Alpha);
 *Learn more:*
 
 * xref:beginner/hello_material.adoc[Hello Material]
-* xref:concepts/how_to_use_materials.adoc[How To Use Materials]
+* xref:core:material/how_to_use_materials.adoc[How To Use Materials]
 
 
 === How do I force or disable culling?
@@ -798,7 +798,7 @@ In your game, add
 settings.setRenderer(AppSettings.LWJGL_OPENGL1)
 ----
 
-to the xref:ROOT:jme3/intermediate/appsettings.adoc[AppSettings] (see details there). +
+to the xref:core:system/appsettings.adoc[AppSettings] (see details there). +
 For the jMonkeyEngine SDK itself, choose Options > OpenGL, and check OpenGL1.