Added documentation on the basic structure of the TSCN file format

development/file_formats/index.rst

@@ -0,0 +1,8 @@
+Godot File Formats
+==================
+
+.. toctree::
+   :maxdepth: 1
+   :name: toc-devel-file-formats
+
+   tscn.rst

development/file_formats/tscn.rst

@@ -0,0 +1,193 @@
+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 :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.
+
+For those looking for a complete description, the parsing is handled in the
+file `scene_format_text.cpp <https://github.com/godotengine/godot/blob/master/scene/resources/scene_format_text.cpp>`_
+in the class :code:`ResourceFormatLoaderText`
+
+
+File Structure
+--------------
+
+There are five main sections inside the TSCN File:
+
+0. File Descriptor
+1. External resources 
+2. Internal resources
+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 it's 
+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 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 .....]`
+
+
+Entries inside the file
+~~~~~~~~~~~~~~~~~~~~~~~
+A heading looks like:
+:code:`[<resource_type> key=value key=value key=value ...]`
+Where resource_type is one of:
+
+- 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 
+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 )
+
+
+Resources
+---------
+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
+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)`
+
+
+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
+
+Godot alway 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. 
+
+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]
+
+
+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 very 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:
+
+::
+
+    [sub_resource  type="CapsuleShape" id=2]
+
+    radius = 0.5
+    height = 3.0
+    
+Some internal resource 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.
+
+Unfortunately, documentation on the formats for these subresources is
+completely absent, and while some can be found through inspecting resources of
+saved files, but others can only be found by looking through Godot's source.
+
+
+The Scene Tree
+--------------
+
+The scene tree is made up of ... nodes! The heading of each node consists of
+it's name, parent and (most of the time) a type. For example
+:code:`[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
+
+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).
+::
+
+    [node name="Player" type="Spatial"]             ; The scene root
+    [node name="Arm" parent="." type="Spatial"]     ; Parented to the scene root
+    [node name="Hand" parent="Arm" type="Spatial"]
+    [node name="Finger" parent="Arm/Hand" type="Spatial"]
+    
+Similar to the internal resource, the content for each node is currently 
+undocumented. Fortunately it is very 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"]
+
+    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"]
+
+    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="."]
+
+    light_energy = 1.0
+    light_specular = 1.0
+    transform = Transform( -0.29086464643478394 , -0.7711008191108704 , 0.5663931369781494 , -0.05518905818462372 , 0.6045246720314026 , 0.7946722507476807 , -0.9551711678504944 , 0.199883371591568 , -0.21839118003845215 ,4.076245307922363 ,7.3235554695129395 ,-1.0054539442062378  )
+    omni_range = 30
+    shadow_enabled = true
+    light_negative = false
+    light_color = Color( 1.0, 1.0, 1.0, 1.0 )
+
+
+    [node  type="Camera" name="Camera" parent="."]
+
+    projection = 0
+    near = 0.10000000149011612
+    fov = 50
+    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
+

index.rst

@@ -80,6 +80,7 @@ The main documentation for the site is organized into the following sections:
 
    development/compiling/index
    development/cpp/index
+   development/file_formats/index
 
 
 .. toctree::