Improve the "TSCN file format" page

This also mentions the ability to write single-line comments in
TSCN/TRES files.

development/file_formats/tscn.rst

@@ -1,24 +1,24 @@
 TSCN file format
 ================
 
-A :code:`.tscn` File format is the "Text SCeNe" file format and represents
-a single scene-tree inside Godot. TSCN files have the advantage of being
-nearly human-readable and easy for version control systems to manage. During
-import the TSCN files are compiled into binary :code:`.scn` files stored
-inside the .import folder. This reduces the data size and speed up loading.
+The TSCN (text scene) file format represents a single scene tree inside
+Godot. TSCN files have the advantage of being mostly human-readable and easy for
+version control systems to manage. During import, TSCN files are compiled into
+binary ``.scn`` files stored inside the .import folder. This reduces the data
+size and speeds up loading.
 
-The :code:`.escn` file format is identical to the TSCN file format, but is used to
-indicate to Godot that the file has been exported from another program and
-should not be edited by the user from within Godot.
+The ESCN (exported scene) file format is identical to the TSCN file format, but
+is used to indicate to Godot that the file has been exported from another
+program and should not be edited by the user from within Godot.
 
-For those looking for a complete description, the parsing is handled in the
-file `resource_format_text.cpp <https://github.com/godotengine/godot/blob/master/scene/resources/resource_format_text.cpp>`_
-in the class :code:`ResourceFormatLoaderText`
+For those looking for a complete description, the parsing is handled in the file
+`resource_format_text.cpp <https://github.com/godotengine/godot/blob/master/scene/resources/resource_format_text.cpp>`_
+in the ``ResourceFormatLoaderText`` class.
 
 File structure
 --------------
 
-There are five main sections inside the TSCN File:
+There are five main sections inside the TSCN file:
 
 0. File Descriptor
 1. External resources
@@ -26,31 +26,33 @@ There are five main sections inside the TSCN File:
 3. Nodes
 4. Connections
 
-The file descriptor looks like :code:`[gd_scene load_steps=1 format=2]` And
-should be the first entry in the file. The load_steps parameter should (in
-theory) be the number of resources within the file, though in practice its
-value seems not to matter.
+The file descriptor looks like ``[gd_scene load_steps=1 format=2]`` and should
+be the first entry in the file. The ``load_steps`` parameter should (in theory)
+be the number of resources within the file. However, in practice, its value seems
+not to matter.
 
-These sections should appear in order, but it can be hard to distinguish
-them. The only difference between them is the first element in the heading
-for all of the items in the section.
-For example, the heading of all external resources should start with
-:code:`[ext_resource .....]`
+These sections should appear in order, but it can be hard to distinguish them.
+The only difference between them is the first element in the heading for all of
+the items in the section. For example, the heading of all external resources
+should start with ``[ext_resource .....]``.
+
+A TSCN file may contain single-line comments starting with a semicolon (``;``).
+However, comments will be discarded when saving the file using the Godot editor.
 
 Entries inside the file
 ~~~~~~~~~~~~~~~~~~~~~~~
 
-A heading looks like:
-:code:`[<resource_type> key=value key=value key=value ...]`
-Where resource_type is one of:
+A heading looks like
+``[<resource_type> key=value key=value key=value ...]``
+where resource_type is one of:
 
-- ext_resource
-- sub_resource
-- node
-- connection
+- ``ext_resource``
+- ``sub_resource``
+- ``node``
+- ``connection``
 
-Underneath every heading comes zero or more :code:`key = value` pairs. The
-values can be complex datatypes such as arrays, transformations, colors, and
+Below every heading comes zero or more ``key = value`` pairs. The
+values can be complex datatypes such as Arrays, Transforms, Colors, and
 so on. For example, a spatial node looks like:
 
 ::
@@ -58,27 +60,29 @@ so on. For example, a spatial node looks like:
     [node name="Cube" type="Spatial" parent="."]
     transform=Transform( 1.0, 0.0, 0.0 ,0.0, 1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0 )
 
+
 The scene tree
 --------------
 
-The scene tree is made up of... nodes! The heading of each node consists of
+The scene tree is made up of… nodes! The heading of each node consists of
 its name, parent and (most of the time) a type. For example
-:code:`[node type="Camera" name="PlayerCamera" parent="Player/Head"]`
+``[node type="Camera" name="PlayerCamera" parent="Player/Head"]``
 
 Other valid keywords include:
 
- - instance
- - instance_placeholder
- - owner
- - index (if two nodes have the same name)
- - groups
+ - ``instance``
+ - ``instance_placeholder``
+ - ``owner``
+ - ``index`` (if two nodes have the same name)
+ - ``groups``
 
-The first node in the file should not have the :code:`parent=Path/To/Node`
-entry in it's heading, and it is the scene root. All scene files should have
-exactly one scene root. It it does not, Godot will fail to import the file.
-The parent path of other nodes should be absolute, but without the scene
-root's name. If it is a direct child of the scene root, it should be
-:code:`"."`. Here is an example scene tree (but without any node content).
+The first node in the file, which is also the scene root, must not have a
+``parent=Path/To/Node`` entry in its heading. All scene files should have
+exactly *one* scene root. If it doesn't, Godot will fail to import the file.
+The parent path of other nodes should be absolute, but shouldn't contain
+the scene root's name. If the node is a direct child of the scene root,
+the path should be ``"."``. Here is an example scene tree
+(but without any node content):
 
 ::
 
@@ -87,25 +91,26 @@ root's name. If it is a direct child of the scene root, it should be
     [node name="Hand" parent="Arm" type="Spatial"]
     [node name="Finger" parent="Arm/Hand" type="Spatial"]
 
+
 Similar to the internal resource, the document for each node is currently
-incomplete. Fortunately it is easy to find out because you can simply
+incomplete. Fortunately, it is easy to find out because you can simply
 save a file with that node in it. Some example nodes are:
 
 ::
 
-    [node  type="CollisionShape" name="SphereCollision" parent="SpherePhysics"]
+    [node type="CollisionShape" name="SphereCollision" parent="SpherePhysics"]
 
     shape = SubResource(8)
     transform = Transform( 1.0 , 0.0 , -0.0 , 0.0 , -4.371138828673793e-08 , 1.0 , -0.0 , -1.0 , -4.371138828673793e-08 ,0.0 ,0.0 ,-0.0  )
 
 
-    [node  type="MeshInstance" name="Sphere" parent="SpherePhysics"]
+    [node type="MeshInstance" name="Sphere" parent="SpherePhysics"]
 
     mesh = SubResource(9)
     transform = Transform( 1.0 , 0.0 , -0.0 , 0.0 , 1.0 , -0.0 , -0.0 , -0.0 , 1.0 ,0.0 ,0.0 ,-0.0  )
 
 
-    [node  type="OmniLight" name="Lamp" parent="."]
+    [node type="OmniLight" name="Lamp" parent="."]
 
     light_energy = 1.0
     light_specular = 1.0
@@ -116,7 +121,7 @@ save a file with that node in it. Some example nodes are:
     light_color = Color( 1.0, 1.0, 1.0, 1.0 )
 
 
-    [node  type="Camera" name="Camera" parent="."]
+    [node type="Camera" name="Camera" parent="."]
 
     projection = 0
     near = 0.10000000149011612
@@ -124,14 +129,15 @@ save a file with that node in it. Some example nodes are:
     transform = Transform( 0.6859206557273865 , -0.32401350140571594 , 0.6515582203865051 , 0.0 , 0.8953956365585327 , 0.44527143239974976 , -0.7276763319969177 , -0.3054208755493164 , 0.6141703724861145 ,14.430776596069336 ,10.093015670776367 ,13.058500289916992  )
     far = 100.0
 
+
 NodePath
 ~~~~~~~~
 
-A tree structure is not enough to represent the whole scene, Godot use
-a :code:`NodePath(Path/To/Node)` structure to refer to another node or
-attribute of the node anywhere in the scene tree. Some typical usages of
-NodePath like mesh node use :code:`NodePath()` to point to its skeleton,
-animation track use :code:`NodePath()` points to animated attribute in node.
+A tree structure is not enough to represent the whole scene. Godot uses a
+``NodePath(Path/To/Node)`` structure to refer to another node or attribute of
+the node anywhere in the scene tree. For instance, MeshInstance uses
+``NodePath()`` to point to its skeleton. Likewise, Animation tracks use
+``NodePath()`` to point to node properties to animate.
 
 ::
 
@@ -140,6 +146,7 @@ animation track use :code:`NodePath()` points to animated attribute in node.
     mesh = SubResource(1)
     skeleton = NodePath("..:")
 
+
 ::
 
     [sub_resource id=3 type="Animation"]
@@ -149,33 +156,30 @@ animation track use :code:`NodePath()` points to animated attribute in node.
     tracks/0/path = NodePath("Cube:")
     ...
 
+
 Skeleton
 ~~~~~~~~
 
-Skeleton node inherits Spatial node, besides that it may have a list
-of bones described in key, value pair in the format :code:`bones/Id/Attribute=Value`,
-attributes of bone consists of
-
-- name
-- parent
-- rest
-- pose
-- enabled
-- bound_children
-
-1) :code:`name` must put as the first attribute of each bone
-
-2) :code:`parent` is the index of parent bone in the bone list, with parent index,
-   the bone list is built to a bone tree
-
-3) :code:`rest` is the transform matrix of bone in rest position
+The Skeleton node inherits the Spatial node, but also may have a list of bones
+described in key-value pairs in the format ``bones/Id/Attribute=Value``. The
+bone attributes consist of:
 
-4) :code:`pose` is the pose matrix use :code:`rest` as basis
+- ``name``
+- ``parent``
+- ``rest``
+- ``pose``
+- ``enabled``
+- ``bound_children``
 
-5) :code:`bound_children` is a list of NodePath() points to
-   BoneAttachments belong to this bone
+1. ``name`` must be the first attribute of each bone.
+2. ``parent`` is the index of parent bone in the bone list, with parent index,
+   the bone list is built to a bone tree.
+3. ``rest`` is the transform matrix of bone in its "resting" position.
+4. ``pose`` is the pose matrix; use ``rest`` as the basis.
+5. ``bound_children`` is a list of ``NodePath()`` which point to
+   BoneAttachments belonging to this bone.
 
-An example of a skeleton node with two bones:
+Here's an example of a skeleton node with two bones:
 
 ::
 
@@ -194,13 +198,14 @@ An example of a skeleton node with two bones:
     bones/1/enabled = true
     bones/1/bound_children = [  ]
 
+
 BoneAttachment
 ~~~~~~~~~~~~~~
 
 BoneAttachment node is an intermediate node to describe some node being parented
-to a single bone in Skeleton node. The BoneAttachment has a :code:`bone_name=NameOfBone`,
-and the corresponding bone being the parent has the BoneAttachment node
-in its :code:`bound_children` list.
+to a single bone in a Skeleton node. The BoneAttachment has a
+``bone_name=NameOfBone`` attribute, and the corresponding bone being the parent has the
+BoneAttachment node in its ``bound_children`` list.
 
 An example of one MeshInstance parented to a bone in Skeleton:
 
@@ -225,13 +230,15 @@ An example of one MeshInstance parented to a bone in Skeleton:
     mesh = SubResource(1)
     transform = Transform(1.0, 0.0, 0.0, 0.0, 1.86265e-09, 1.0, 0.0, -1.0, 0.0, 0.0219986, -0.0343127, 2.25595)
 
+
 AnimationPlayer
 ~~~~~~~~~~~~~~~
 
-AnimationPlayer works as an animation lib. it has animations listed in the format
-:code:`anim/Name=SubResource(ResourceId)`, each refers to a Animation
-internal resource. All the animation resources use the root node of AnimationPlayer.
-The root node is stored as :code:`root_node=NodePath(Path/To/Node)`.
+AnimationPlayer works as an animation library. It stores animations listed in
+the format ``anim/Name=SubResource(ResourceId)``; each line refers to an
+Animation resource. All the animation resources use the root node of
+AnimationPlayer. The root node is stored as
+``root_node=NodePath(Path/To/Node)``.
 
 ::
 
@@ -245,6 +252,7 @@ The root node is stored as :code:`root_node=NodePath(Path/To/Node)`.
     anims/default = SubResource( 2 )
     blend_times = [  ]
 
+
 Resources
 ---------
 
@@ -252,29 +260,24 @@ Resources are components that make up the nodes. For example, a MeshInstance
 node will have an accompanying ArrayMesh resource. The ArrayMesh resource
 may be either internal or external to the TSCN file.
 
-References to the resources are handled by id numbers in the resources heading.
-External resources and internal resource are referred to with
-:code:`ExtResource(id)` and :code:`SubResource(id)`. Because there have
-different methods to refer to internal and external resource, you can have
+References to the resources are handled by ``id`` numbers in the resource's
+heading. External resources and internal resources are referred to with
+``ExtResource(id)`` and ``SubResource(id)``, respectively. Because there
+have different methods to refer to internal and external resources, you can have
 the same ID for both an internal and external resource.
 
-For example, to refer to the resource
-:code:`[ext_resource id=3 type="PackedScene" path=....]` you would use
-:code:`ExtResource(3)`
+For example, to refer to the resource ``[ext_resource id=3 type="PackedScene"
+path=....]``, you would use ``ExtResource(3)``.
 
 External resources
 ~~~~~~~~~~~~~~~~~~
 
 External resources are links to resources not contained within the TSCN file
-itself. An external resource consists of:
-
- - A path
- - A type
- - An ID
+itself. An external resource consists of a path, a type and an ID.
 
 Godot always generates absolute paths relative to the resource directory and
-thus prefixed with :code:`res://`, but paths relative to the TSCN file's
-location are also valid.
+thus prefixed with ``res://``, but paths relative to the TSCN file's location
+are also valid.
 
 Some example external resources are:
 
@@ -283,14 +286,19 @@ Some example external resources are:
     [ext_resource path="res://characters/player.dae" type="PackedScene" id=1]
     [ext_resource path="metal.tres" type="Material" id=2]
 
+
+Like TSCN files, a TRES file may contain single-line comments starting with a
+semicolon (``;``). However, comments will be discarded when saving the resource
+using the Godot editor.
+
 Internal resources
 ~~~~~~~~~~~~~~~~~~
 
-A TSCN file can contain meshes, materials and other data, and these are
-contained in the internal resources section of the file. The heading
-for an internal resource looks similar to those of external resources, but
-does not have a path. Internal resources also have :code:`key=value` pairs
-under each heading. For example, a capsule collision shape looks like:
+A TSCN file can contain meshes, materials and other data. These are contained in
+the *internal resources* section of the file. The heading for an internal
+resource looks similar to those of external resources, except that it doesn't
+have a path. Internal resources also have ``key=value`` pairs under each
+heading. For example, a capsule collision shape looks like:
 
 ::
 
@@ -299,45 +307,46 @@ under each heading. For example, a capsule collision shape looks like:
     radius = 0.5
     height = 3.0
 
-Some internal resource contain links to other internal resources (such as a
+
+Some internal resources contain links to other internal resources (such as a
 mesh having a material). In this case, the referring resource must appear
-before the reference to it. Thus, in the internal resources section of the
-file, order does matter.
+*before* the reference to it. This means that order matters in the file's
+internal resources section.
 
-Unfortunately, documentation on the formats for these subresources is not
-complete, and while some can be found through inspecting resources of
-saved files, others can only be found by looking through Godot's source.
+Unfortunately, documentation on the formats for these subresources isn't
+complete. Some examples can be found by inspecting saved resource files, but
+others can only be found by looking through Godot's source.
 
 ArrayMesh
 ~~~~~~~~~
 
-ArrayMesh consists of several surfaces, each in the format :code:`surface\Index={}`,
-each surface is a set of vertex and a material.
+ArrayMesh consists of several surfaces, each in the format ``surface\Index={}``.
+Each surface is a set of vertices and a material.
 
-TSCN support two format of surface,
+TSCN files support two surface formats:
 
-1) for the old format, each surface has three essential keys:
+1. For the old format, each surface has three essential keys:
 
-- primitive
-- arrays
-- morph_arrays
+- ``primitive``
+- ``arrays``
+- ``morph_arrays``
 
-    i) :code:`primitive` is an enumerate variable, :code:`primitive=4` which is
-       PRIMITIVE_TRIANGLES is frequently used.
+    i. ``primitive`` is an enumerate variable, ``primitive=4`` which is
+       ``PRIMITIVE_TRIANGLES`` is frequently used.
 
-    ii) :code:`arrays` as the name suggests is an array of array, it contains:
+    ii. ``arrays`` is a two-dimensional array, it contains:
 
-        1) An array of vertex position
-        2) Tangents array
-        3) Vertex color array
-        4) UV array 1
-        5) UV array 2
-        6) Bone index array
-        7) Bone weight array
-        8) Vertex index array
+        1. Vertex positions array
+        2. Tangents array
+        3. Vertex colors array
+        4. UV array 1
+        5. UV array 2
+        6. Bone indexes array
+        7. Bone weights array
+        8. Vertex indexes array
 
-    iii) :code:`morph_arrays` is an array of morph, each morph is exactly an
-         :code:`arrays` without vertex index array.
+    iii. ``morph_arrays`` is an array of morphs. Each morph is exactly an
+         ``arrays`` without the vertex indexes array.
 
 An example of ArrayMesh:
 
@@ -361,54 +370,52 @@ An example of ArrayMesh:
         "morph_arrays":[]
     }
 
+
 Animation
 ~~~~~~~~~
 
-An animation resource consists of tracks. Besides, it has 'length', 'loop' and
-'step' applied to all the tracks.
-
-- length
-- loop
-- step
+An animation resource consists of tracks. Besides, it has ``length``, ``loop``
+and ``step`` applied to all the tracks.
 
-1) :code:`length` and :code:`step` are both time in seconds
+1. ``length`` and ``step`` are both durations in seconds.
 
-Each track is described by a list of (key, value) pairs in the format :code:`tracks/Id/Attribute`,
-it includes:
+Each track is described by a list of key-value pairs in the format
+``tracks/Id/Attribute``. Each track includes:
 
-- type
-- path
-- interp
-- keys
-- loop_wrap
-- imported
-- enabled
+- ``type``
+- ``path``
+- ``interp``
+- ``keys``
+- ``loop_wrap``
+- ``imported``
+- ``enabled``
 
-1) The :code:`type` must be put as the first attribute of each track.
-   The value of :code:`type` can be:
+1. The ``type`` must be the first attribute of each track.
+   The value of ``type`` can be:
 
-    - 'transform'
-    - 'value'
-    - 'method'
+    - ``transform``
+    - ``value``
+    - ``method``
 
-2) The :code:`path` has the format :code:`NodePath(Path/To/Node:Attribute)`.
-   It is the path from animation root node (property of AnimationPlayer) to the
-   animated node or attribute.
+2. The ``path`` has the format ``NodePath(Path/To/Node:attribute)``.
+   It's the path to the animated node or attribute, relative to the root node
+   defined in the AnimationPlayer.
 
-3) The :code:`interp` is the method to interpolate frames from the keyframes.
+3. The ``interp`` is the method to interpolate frames from the keyframes.
    it is a enum variable and can has value:
 
     - 0 (constant)
     - 1 (linear)
     - 2 (cubic)
 
-4) The :code:`keys` is the keyframes, it appears as a PoolRealArray()
-   but have different structure for track with different type
+4. The ``keys`` correspond to the keyframes. It appears as a ``PoolRealArray()``,
+   but may have a different structure for tracks with different types.
 
-    - A transform track use every 12 real number in the :code:`keys` to describte a keyframe.
-      The first number is the timestamp, the second number is the transition (default 1.0
-      in transform track), followed by a three number translation vector, followed by
-      four number rotation quaternion (x,y,z,w) and finally a three number scale vector.
+    - A Transform track uses every 12 real numbers in the ``keys`` to describe
+      a keyframe. The first number is the timestamp. The second number is the
+      transition followed by a 3-number translation vector, followed by a
+      4-number rotation quaternion (X, Y, Z, W) and finally a 3-number
+      scale vector. The default transition in a Transform track is 1.0.
 
 ::