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Binary serialization API

Introduction

Redot has a serialization API based on Variant. It's used for converting data types to an array of bytes efficiently. This API is exposed via the global bytes_to_var() and var_to_bytes() functions, but it is also used in the get_var and store_var methods of FileAccess as well as the packet APIs for PacketPeer. This format is not used for binary scenes and resources.

Full Objects vs Object instance IDs

If a variable is serialized with full_objects = true, then any Objects contained in the variable will be serialized and included in the result. This is recursive.

If full_objects = false, then only the instance IDs will be serialized for any Objects contained in the variable.

Packet specification

The packet is designed to be always padded to 4 bytes. All values are little-endian-encoded. All packets have a 4-byte header representing an integer, specifying the type of data.

The lowest value two bytes are used to determine the type, while the highest value two bytes contain flags:

base_type = val & 0xFFFF;
flags = val >> 16;

Type	Value
0	null
1	bool
2	integer
3	float
4	string
5	vector2
6	rect2
7	vector3
8	transform2d
9	plane
10	quaternion
11	aabb
12	basis
13	transform3d
14	color
15	node path
16	rid
17	object
18	dictionary
19	array
20	raw array
21	int32 array
22	int64 array
23	float32 array
24	float64 array
25	string array
26	vector2 array
27	vector3 array
28	color array
29	max

Following this is the actual packet contents, which varies for each type of packet. Note that this assumes Redot is compiled with single-precision floats, which is the default. If Redot was compiled with double-precision floats, the length of "Float" fields within data structures should be 8, and the offset should be (offset - 4) * 2 + 4. The "float" type itself always uses double precision.

0: null

1: bool

Offset	Len	Type	Description
4	4	Integer	0 for False, 1 for True

2: int

If no flags are set (flags == 0), the integer is sent as a 32 bit integer:

Offset	Len	Type	Description
4	4	Integer	32-bit signed integer

If flag ENCODE_FLAG_64 is set (flags & 1 == 1), the integer is sent as a 64-bit integer:

Offset	Len	Type	Description
4	8	Integer	64-bit signed integer

3: float

If no flags are set (flags == 0), the float is sent as a 32 bit single precision:

Offset	Len	Type	Description
4	4	Float	IEEE 754 single-precision float

If flag ENCODE_FLAG_64 is set (flags & 1 == 1), the float is sent as a 64-bit double precision number:

Offset	Len	Type	Description
4	8	Float	IEEE 754 double-precision float

4: String

Offset	Len	Type	Description
4	4	Integer	String length (in bytes)
8	X	Bytes	UTF-8 encoded string

This field is padded to 4 bytes.

5: Vector2

Offset	Len	Type	Description
4	4	Float	X coordinate
8	4	Float	Y coordinate

6: Rect2

Offset	Len	Type	Description
4	4	Float	X coordinate
8	4	Float	Y coordinate
12	4	Float	X size
16	4	Float	Y size

7: Vector3

Offset	Len	Type	Description
4	4	Float	X coordinate
8	4	Float	Y coordinate
12	4	Float	Z coordinate

8: Transform2D

Offset	Len	Type	Description
4	4	Float	The X component of the X column vector, accessed via [0][0]
8	4	Float	The Y component of the X column vector, accessed via [0][1]
12	4	Float	The X component of the Y column vector, accessed via [1][0]
16	4	Float	The Y component of the Y column vector, accessed via [1][1]
20	4	Float	The X component of the origin vector, accessed via [2][0]
24	4	Float	The Y component of the origin vector, accessed via [2][1]

9: Plane

Offset	Len	Type	Description
4	4	Float	Normal X
8	4	Float	Normal Y
12	4	Float	Normal Z
16	4	Float	Distance

10: Quaternion

Offset	Len	Type	Description
4	4	Float	Imaginary X
8	4	Float	Imaginary Y
12	4	Float	Imaginary Z
16	4	Float	Real W

11: AABB

Offset	Len	Type	Description
4	4	Float	X coordinate
8	4	Float	Y coordinate
12	4	Float	Z coordinate
16	4	Float	X size
20	4	Float	Y size
24	4	Float	Z size

12: Basis

Offset	Len	Type	Description
4	4	Float	The X component of the X column vector, accessed via [0][0]
8	4	Float	The Y component of the X column vector, accessed via [0][1]
12	4	Float	The Z component of the X column vector, accessed via [0][2]
16	4	Float	The X component of the Y column vector, accessed via [1][0]
20	4	Float	The Y component of the Y column vector, accessed via [1][1]
24	4	Float	The Z component of the Y column vector, accessed via [1][2]
28	4	Float	The X component of the Z column vector, accessed via [2][0]
32	4	Float	The Y component of the Z column vector, accessed via [2][1]
36	4	Float	The Z component of the Z column vector, accessed via [2][2]

13: Transform3D

Offset	Len	Type	Description
4	4	Float	The X component of the X column vector, accessed via [0][0]
8	4	Float	The Y component of the X column vector, accessed via [0][1]
12	4	Float	The Z component of the X column vector, accessed via [0][2]
16	4	Float	The X component of the Y column vector, accessed via [1][0]
20	4	Float	The Y component of the Y column vector, accessed via [1][1]
24	4	Float	The Z component of the Y column vector, accessed via [1][2]
28	4	Float	The X component of the Z column vector, accessed via [2][0]
32	4	Float	The Y component of the Z column vector, accessed via [2][1]
36	4	Float	The Z component of the Z column vector, accessed via [2][2]
40	4	Float	The X component of the origin vector, accessed via [3][0]
44	4	Float	The Y component of the origin vector, accessed via [3][1]
48	4	Float	The Z component of the origin vector, accessed via [3][2]

14: Color

Offset	Len	Type	Description
4	4	Float	Red (typically 0..1, can be above 1 for overbright colors)
8	4	Float	Green (typically 0..1, can be above 1 for overbright colors)
12	4	Float	Blue (typically 0..1, can be above 1 for overbright colors)
16	4	Float	Alpha (0..1)

15: NodePath

Offset	Len	Type	Description
4	4	Integer	String length, or new format (val&0x80000000!=0 and NameCount=val&0x7FFFFFFF)

For old format:

Offset	Len	Type	Description
8	X	Bytes	UTF-8 encoded string

Padded to 4 bytes.

For new format:

Offset	Len	Type	Description
4	4	Integer	Sub-name count
8	4	Integer	Flags (absolute: val&1 != 0 )

For each Name and Sub-Name

Offset	Len	Type	Description
X+0	4	Integer	String length
X+4	X	Bytes	UTF-8 encoded string

Every name string is padded to 4 bytes.

16: RID (unsupported)

17: Object

An Object could be serialized in three different ways: as a null value, with full_objects = false, or with full_objects = true.

A null value

Offset	Len	Type	Description
4	4	Integer	Zero (32-bit signed integer)

full_objects disabled

Offset	Len	Type	Description
4	8	Integer	The Object instance ID (64-bit signed integer)

full_objects enabled

Offset	Len	Type	Description
4	4	Integer	Class name (String length)
8	X	Bytes	Class name (UTF-8 encoded string)
X+8	4	Integer	The number of properties that are serialized

For each property:

Offset	Len	Type	Description
Y	4	Integer	Property name (String length)
Y+4	Z	Bytes	Property name (UTF-8 encoded string)
Y+4+Z	W	<variable>	Property value, using this same format

Note

Not all properties are included. Only properties that are configured with the PROPERTY_USAGE_STORAGE flag set will be serialized. You can add a new usage flag to a property by overriding the _get_property_list method in your class. You can also check how property usage is configured by calling Object._get_property_list See PropertyUsageFlags for the possible usage flags.

18: Dictionary

Offset	Len	Type	Description
4	4	Integer	val&0x7FFFFFFF = elements, val&0x80000000 = shared (bool)

Then what follows is, for amount of "elements", pairs of key and value, one after the other, using this same format.

19: Array

Offset	Len	Type	Description
4	4	Integer	val&0x7FFFFFFF = elements, val&0x80000000 = shared (bool)

Then what follows is, for amount of "elements", values one after the other, using this same format.

20: PackedByteArray

Offset	Len	Type	Description
4	4	Integer	Array length (Bytes)
8..8+length	1	Byte	Byte (0..255)

The array data is padded to 4 bytes.

21: PackedInt32Array

Offset	Len	Type	Description
4	4	Integer	Array length (Integers)
8..8+length*4	4	Integer	32-bit signed integer

22: PackedInt64Array

Offset	Len	Type	Description
4	8	Integer	Array length (Integers)
8..8+length*8	8	Integer	64-bit signed integer

23: PackedFloat32Array

Offset	Len	Type	Description
4	4	Integer	Array length (Floats)
8..8+length*4	4	Integer	32-bit IEEE 754 single-precision float

24: PackedFloat64Array

Offset	Len	Type	Description
4	4	Integer	Array length (Floats)
8..8+length*8	8	Integer	64-bit IEEE 754 double-precision float

25: PackedStringArray

Offset	Len	Type	Description
4	4	Integer	Array length (Strings)

For each String:

Offset	Len	Type	Description
X+0	4	Integer	String length
X+4	X	Bytes	UTF-8 encoded string

Every string is padded to 4 bytes.

26: PackedVector2Array

Offset	Len	Type	Description
4	4	Integer	Array length
8..8+length*8	4	Float	X coordinate
8..12+length*8	4	Float	Y coordinate

27: PackedVector3Array

Offset	Len	Type	Description
4	4	Integer	Array length
8..8+length*12	4	Float	X coordinate
8..12+length*12	4	Float	Y coordinate
8..16+length*12	4	Float	Z coordinate

28: PackedColorArray

Offset	Len	Type	Description
4	4	Integer	Array length
8..8+length*16	4	Float	Red (typically 0..1, can be above 1 for overbright colors)
8..12+length*16	4	Float	Green (typically 0..1, can be above 1 for overbright colors)
8..16+length*16	4	Float	Blue (typically 0..1, can be above 1 for overbright colors)
8..20+length*16	4	Float	Alpha (0..1)