Move advanced import settings to their own page

tutorials/assets_pipeline/importing_3d_scenes/advanced_import_settings.rst

@@ -0,0 +1,247 @@
+.. _doc_advanced_import_settings:
+
+Advanced Import Settings
+========================
+
+While the regular import panel provides many essential options for imported 3D
+models, the advanced import settings provides per object options, model previews,
+and animation previews. To open it select the :button:`Advanced...` button at the
+bottom of the import dock.
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_button.webp
+   :align: center
+
+This is available for 3D models imported as scenes, as well as animation libraries.
+
+.. note::
+
+    This page does not go over options also available in the import dock, or anything
+    outside of the advanced import settings. For information on those please read the
+    :ref:`doc_importing_3d_scenes_import_configuration` page.
+
+Using the Advanced Import Settings dialog
+-----------------------------------------
+
+The first tab you'll see is the **Scene** tab. The options available in the
+panel on the right are identical to the Import dock, but you have access to a 3D
+preview. The 3D preview can be rotated by holding down the left mouse button
+then dragging the mouse. Zoom can be adjusted using the mouse wheel.
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_scene.webp
+   :align: center
+   :alt: Advanced Import Settings dialog (Scene tab)
+
+   Advanced Import Settings dialog (Scene tab).
+   Credit: `Modern Arm Chair 01 - Poly Haven <https://polyhaven.com/a/modern_arm_chair_01>`__
+
+Configuring node import options
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You can select individual nodes that compose the scene while in the **Scene**
+tab using the tree view at the left:
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_node.webp
+   :align: center
+   :alt: Selecting a node in the Advanced Import Settings dialog (Scene tab)
+
+   Selecting a node in the Advanced Import Settings dialog (Materials tab)
+
+This exposes several per-node import options:
+
+- **Skip Import:** If checked, the node will not be present in the final
+  imported scene. Enabling this disables all other options.
+- **Generate > Physics:** If checked, generates a PhysicsBody3D *parent* node
+  with collision shapes that are *siblings* to the MeshInstance3D node.
+- **Generate > NavMesh:** If checked, generates a NavigationRegion3D *child*
+  node for :ref:`navigation <doc_navigation_overview_3d>`. **Mesh + NavMesh**
+  will keep the original mesh visible, while **NavMesh Only** will only import
+  the navigation mesh (without a visual representation). **NavMesh Only** is
+  meant to be used when you've manually authored a simplified mesh for navigation.
+- **Generate > Occluder:** If checked, generates an OccluderInstance3D *sibling*
+  node for :ref:`occlusion culling <doc_occlusion_culling>` using the mesh's
+  geometry as a basis for the occluder's shape. **Mesh + Occluder** will keep
+  the original mesh visible, while **Occluder Only** will only import the
+  occluder (without a visual representation). **Occluder Only** is meant to be
+  used when you've manually authored a simplified mesh for occlusion culling.
+
+These options are only visible if some of the above options are enabled:
+
+- **Physics > Body Type:** Only visible if **Generate > Physics** is enabled.
+  Controls the PhysicsBody3D that should be created. **Static** creates a
+  StaticBody3D, **Dynamic** creates a RigidBody3D, **Area** creates an Area3D.
+- **Physics > Shape Type:** Only visible if **Generate > Physics** is enabled.
+  **Trimesh** allows for precise per-triangle collision, but it can only be used
+  with a **Static** body type. Other types are less precise and may require
+  manual configuration, but can be used with any body type. For static level
+  geometry, use **Trimesh**. For dynamic geometry, use primitive shapes if
+  possible for better performance, or use one of the convex decomposition modes
+  if the shape is large and complex.
+- **Decomposition > Advanced:** Only visible if **Physics > Shape Type** is
+  **Decompose Convex**. If checked, allows adjusting advanced decomposition
+  options. If disabled, only a preset **Precision** can be adjusted (which is
+  usually sufficient).
+- **Decomposition > Precision:** Only visible if **Physics > Shape Type** is
+  **Decompose Convex**. Controls the precision to use for convex decomposition.
+  Higher values result in more detailed collision, at the cost of slower
+  generation and increased CPU usage during physics simulation. To improve
+  performance, it's recommended to keep this value as low as possible for your
+  use cases.
+- **Occluder > Simplification Distance:** Only visible if **Generate >
+  Occluder** is set to **Mesh + Occluder** or **Occluder Only**. Higher values
+  result in an occluder mesh with fewer vertices (resulting in decreased CPU
+  utilization), at the cost of more occlusion culling issues (such as false
+  positives or false negatives). If you run into objects disappearing when they
+  shouldn't when the camera is near a certain mesh, try decreasing this value.
+
+Configuring mesh and material import options
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In the Advanced Import Settings dialog, there are 2 ways to select individual
+meshes or materials:
+
+- Switch to the **Meshes** or **Materials** tab in the top-left corner of the dialog.
+- Stay in the **Scene** tab, but unfold the options on the tree view on the
+  left. After choosing a mesh or material, this presents the same information as
+  the **Meshes** and **Materials** tabs, but in a tree view instead of a list.
+
+If you select a mesh, different options will appear in the panel on the right:
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_meshes.webp
+   :align: center
+   :alt: Advanced Import Settings dialog (Meshes tab)
+
+   Advanced Import Settings dialog (Meshes tab)
+
+The options are as follows:
+
+- **Save to File:** Saves the :ref:`class_Mesh` *resource* to an external file
+  (this isn't a scene file). You generally don't need to use this for placing
+  the mesh in a 3D scene – instead, you should instance the 3D scene directly.
+  However, having direct access to the Mesh resource is useful for specific
+  nodes, such as :ref:`class_MeshInstance3D`, :ref:`class_MultiMeshInstance3D`,
+  :ref:`class_GPUParticles3D` or :ref:`class_CPUParticles3D`.
+  - You will also need to specify an output file path using the option that
+  appears after enabling **Save to File**. It's recommended to use the ``.res``
+  output file extension for smaller file sizes and faster loading speeds, as
+  ``.tres`` is inefficient for writing large amounts of data.
+- **Generate > Shadow Meshes:** Per-mesh override for the **Meshes > Create
+  Shadow Meshes** scene-wide import option described in
+  :ref:`doc_importing_3d_scenes_using_the_import_dock`. **Default** will use the
+  scene-wide import option, while **Enable** or **Disable** can forcibly enable
+  or disable this behavior on a specific mesh.
+- **Generate > Lightmap UV:** Per-mesh override for the **Meshes > Light
+  Baking** scene-wide import option described in
+  :ref:`doc_importing_3d_scenes_using_the_import_dock`. **Default** will use the
+  scene-wide import option, while **Enable** or **Disable** can forcibly enable
+  or disable this behavior on a specific mesh.
+  - Setting this to **Enable** on a scene with the **Static** light baking mode
+  is equivalent to configuring this mesh to use **Static Lightmaps**. Setting this
+  to **Disable** on a scene with the **Static Lightmaps** light baking mode is
+  equivalent to configuring this mesh to use **Static** instead.
+- **Generate > LODs:** Per-mesh override for the **Meshes > Generate LODs**
+  scene-wide import option described in
+  :ref:`doc_importing_3d_scenes_using_the_import_dock`. **Default** will use the
+  scene-wide import option, while **Enable** or **Disable** can forcibly enable
+  or disable this behavior on a specific mesh.
+- **LODs > Normal Merge Angle:** The minimum angle difference between two
+  vertices required to preserve a geometry edge in mesh LOD generation. If
+  running into visual issues with LOD generation, decreasing this value may help
+  (at the cost of less efficient LOD generation).
+
+If you select a material, only one option will appear in the panel on the right:
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_materials.webp
+   :align: center
+   :alt: Advanced Import Settings dialog (Materials tab)
+
+   Advanced Import Settings dialog (Materials tab)
+
+When **Use External** is checked and an output path is specified, this lets you
+use an external material instead of the material that is included in the
+original 3D scene file; see the section below.
+
+Extracting materials to separate files
+--------------------------------------
+
+While Godot can import materials authored in 3D modeling software, the default
+configuration may not be suitable for your needs. For example:
+
+- You want to configure material features not supported by your 3D application.
+- You want to use a different texture filtering mode, as this option is
+  configured in the material since Godot 4.0 (and not in the image).
+- You want to replace one of the materials with an entirely different material,
+  such as a custom shader.
+
+To be able to modify the 3D scene's materials in the Godot editor, you need to
+use *external* material resources.
+
+In the top-left corner of the Advanced Import Settings dialog, choose
+**Actions… > Extract Materials**:
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_extract_materials.webp
+   :align: center
+   :alt: Extracting all built-in materials to external resources in the Advanced Import Settings dialog
+
+   Extracting all built-in materials to external resources in the Advanced Import Settings dialog
+
+After choosing this option, select a folder to extract material ``.tres`` files
+to, then confirm the extraction:
+
+.. figure:: img/importing_3d_scenes_advanced_import_settings_extract_materials_confirm.webp
+   :align: center
+   :alt: Confirming material extraction in the Advanced Import Settings subdialog
+
+   Confirming material extraction in the Advanced Import Settings subdialog
+
+.. note::
+
+    After extracting materials, the 3D scene will automatically be configured to
+    use external material references. As a result, you don't need to manually
+    enable **Use External** on every material to make the external ``.tres``
+    material effective.
+
+When **Use External** is enabled, remember that the Advanced Import Settings
+dialog will keep displaying the mesh's original materials (the ones designed in
+the 3D modeling software). This means your customizations to the materials won't
+be visible within this dialog. To preview your modified materials, you need to
+place the imported 3D scene in another scene using the editor.
+
+Godot will not overwrite changes made to extracted materials when the source 3D
+scene is reimported. However, if the material name is changed in the source 3D
+file, the link between the original material and the extracted material will be
+lost. As a result, you'll need to use the Advanced Import Settings dialog to
+associate the renamed material to the existing extracted material.
+
+The above can be done in the dialog's **Materials** tab by selecting the
+material, enabling **Save to File**, then specifying the save path using the
+**Path** option that appears after enabling **Save to File**.
+
+Animation options
+-----------------
+
+Several extra options are available for the generated :ref:`class_AnimationPlayer`
+nodes, as well as their individual animations when they're selected in the
+**Scene** tab.
+
+Optimizer
+~~~~~~~~~
+
+When animations are imported, an optimizer is run, which reduces the size of the
+animation considerably. In general, this should always be turned on unless you
+suspect that an animation might be broken due to it being enabled.
+
+Save to file
+~~~~~~~~~~~~
+
+By default, animations are saved as built-in. It is possible to save them to a
+file instead. This allows adding custom tracks to the animations and keeping
+them after a reimport.
+
+Slices
+~~~~~~
+
+It is possible to specify multiple animations from a single timeline as slices.
+For this to work, the model must have only one animation that is named
+``default``. To create slices, change the slice amount to something greater than
+zero. You can then name a slice, specify which frames it starts and stops on, and
+choose whether the animation loops or not.