CLYT format

CLYT (.bclyt) is the layout format used on the 3DS. It stands for (Binary) CTR Layout, and is similar to the RLYT format used on the Wii.

Header

Offset	Size	Type	Description
0x00	0x4	String	Signature (CLYT)
0x04	0x2	UInt16	Byte Order Mark
0x06	0x2	UInt16	Header Length
0x08	0x4	UInt32	Revision
0x0C	0x4	UInt32	File Size
0x10	0x2	UInt16	Nr Sections
0x12	0x2	UInt16	Padding

lyt1 (Layout 1)

Offset	Size	Type	Description
0x00	0x4	String	Signature (lyt1)
0x04	0x4	UInt32	Section Size
0x08	0x4	UInt32	Origin type Value Meaning 0 Classic 1 Normal
0x0C	0x8	Vector2	Canvas Size

txl1 (Texture List 1)

Offset	Size	Type	Description
0x00	0x4	String	Signature (txl1)
0x04	0x4	UInt32	Section Size
0x08	0x4	UInt32	Nr Textures = N
0x0C	N * 4	UInt32[]	Texture Name Offsets (relative to the start of this array)

After this, the null terminated names follow.

fnl1 (Font List 1)

Offset	Size	Type	Description
0x00	0x4	String	Signature (fnl1)
0x04	0x4	UInt32	Section Size
0x08	0x4	UInt32	Nr Fonts = N
0x0C	N * 4	UInt32[]	Font Name Offsets (relative to the start of this array)

After this, the null terminated names follow.

mat1 (Materials 1)

Offset	Size	Type	Description
0x00	0x4	String	Signature (mat1)
0x04	0x4	UInt32	Section Size
0x08	0x4	UInt32	Nr Materials = N
0x0C	N * 4	UInt32[]	Material Entry Offsets (relative to the start of this section)

After this, the material entries follow.

Offset	Size	Type	Description
0x00	0x14	String	Material Name
0x14	0x4	RGBA8	Tev Color (Buffer Color?)
0x18	0x18	RGBA8[6]	Tev Constant Colors
0x30	0x4	UInt32	Flags / bitfield Bit Flag / data 0-1 Nr texMap 2-3 Nr texMatrix 4-5 Nr texCoordGen 6-8 Nr tevStage 9 Has alphaCompare 10 Has blendMode 11 Use Texture Only

Texture Map Entry

Offset	Size	Type	Description
0x00	0x2	UInt16	Texture Index
0x02	0x1	Byte	Bitfield Bit Data 0-1 Wrap S (Clamp = 0, Repeat = 1, Mirror = 2) 2-3 Min Filter (0 = Near, 1 = Linear)
0x03	0x1	Byte	Bitfield Bit Data 0-1 Wrap T (Clamp = 0, Repeat = 1, Mirror = 2) 2-3 Mag Filter (0 = Near, 1 = Linear)

Texture Matrix Entry

Offset	Size	Type	Description
0x00	0x8	Vector2	Translation
0x08	0x4	Single	Rotation
0x0C	0x8	Vector2	Scale

Texture Coordinate Generation Entry

Offset	Size	Type	Description
0x00	0x1	UInt8	Type Value Meaning 0 2x4 matrix
0x01	0x1	UInt8	Source (N = Tex N, max 2)
0x02	0x2	UInt8[]	Padding

TODO: tevStage, alphaCompare, blendMode, etc...

pan1(Pane 1)

Defines a Null pane, used mostly to keep panes grouped in hierarchies or to control the children of a given pan1 without having to do so individually.

Offset	Size	Type	Description
0x00	0x4	String	Signature (pan1)
0x04	0x4	UInt32	Section Size
0x08	0x1	UInt8	Flags Bit Flag 0 Visible 1 InfluencedAlpha 2 LocationAdjust
0x09	0x1	UInt8	Origin (1 = centered, 2 = right, 3 = left, )
0x0A	0x1	UInt8	Alpha
0x0B	0x1	UInt8	Padding
0x0C	0x10	String	Pane name
0x1C	0x8	String	Data
0x24	0xC	Vector3	Translation
0x30	0xC	Vector3	Rotation
0x3C	0x8	Vector2	Scale
0x44	0x8	Vector2	Size

pic1(Picture 1)

pic1 represents a picture that can be displayed in a layout. The first 0x4C bytes are defined the same as pan1 with minor differences.

Offset	Size	Type	Description
0x00	0x4	String	Signature (pic1)
0x04	0x4	UInt32	Section size (including the texture coordinates)
Same as pan1 from 0x8 to 0x4c
0x4C	0x4	RGBA8	Top left vertex color
0x50	0x4	RGBA8	Top right vertex color
0x54	0x4	RGBA8	Bottom left vertex color
0x58	0x4	RGBA8	Bottom right vertex color
0x5C	0x2	UInt16	Material ID
0x5E	0x2	UInt16	Nr texture coordinates = N
Texture coordinates entry
0x60 + (N-1) * 0x20	0x8	Vector2	Top left vertex texture coordinate
0x64 + (N-1) * 0x20	0x8	Vector2	Top right vertex texture coordinate
0x68 + (N-1) * 0x20	0x8	Vector2	Bottom left vertex texture coordinate
0x6C + (N-1) * 0x20	0x8	Vector2	Bottom right vertex texture coordinate

txt1 (Text 1)

A textbox used in layouts. The first 0x4C bytes are defined the same as pan1 with minor differences.

Offset	Size	Type	Description
0x00	0x4	String	Signature (txt1)
0x04	0x4	UInt32	Section size (including the textbox string)
Same as pan1 from 0x8 to 0x4c
0x4C	0x2	Unknown	Flags (H Direction?)
0x4E	0x2	Unknown	Flags (V Direction?)
0x50	0x4	UInt32	Material ID
0x54	0x2	Unknown	Flags (Line alignment?)
0x56	0x2	Unknown	Padding
0x58	0x4	UInt32	Offset from signature to beginning of the string
0x5C	0x4	RGBA8	Font top color
0x60	0x4	RGBA8	Font bottom color
0x64	0x8	Vector2	Font scale
0x6C	0x4	Float	Horizontal font spacing
0x70	0x4	Float	Vertical font spacing
0x74	User defined	String	Textbox text (must be multiple of 4), can be usd1

wnd1 (Window 1)

A more complex type of image pane, where the user can define the content, the corners and the sides of it, depending on what mode it's set to.

Offset	Size	Type	Description
0x00	0x4	String	Signature (wnd1)
0x04	0x4	UInt32	Section size (including the texture coordinates)
Same as pan1 from 0x8 to 0x4c
0x4C	0x4	float	Coordinate 1
0x50	0x4	float	Coordinate 2
0x54	0x4	float	Coordinate 3
0x58	0x4	float	Coordinate 4
0x5C	0x1	Byte	Number of frames (n)
0x5D	0x1	Byte	Flag
0x5E	0x2	UInt16	Padding
0x60	0x4	UInt32	Window content offset (Points to 0x68)
0x64	0x4	UInt32	Window frame offsets, offset to offsets of the materials for the frames. (W)
0x68	0x4	RGBA8	Content box top left vertex color
0x6C	0x4	RGBA8	Content box top right vertex color
0x70	0x4	RGBA8	Content box bottom left vertex color
0x74	0x4	RGBA8	Content box bottom right vertex color
0x78	0x2	UInt16	Content box Material ID
0x7A	0x2	UInt16	Number of Texture coordinates (N)
Texture coordinates entry
0x7C + (N-1) * 0x20	0x8	Vector2	Top left vertex texture coordinate
0x84 + (N-1) * 0x20	0x8	Vector2	Top right vertex texture coordinate
0x8C + (N-1) * 0x20	0x8	Vector2	Bottom left vertex texture coordinate
0x94 + (N-1) * 0x20	0x8	Vector2	Bottom right vertex texture coordinate
Window frames
0x(W)	0x4 * n	UInt32	Offsets to frame materials
0x(W)	0x4 * n	Window frame	Offset Size Type Description 0x0 UInt16 0x2 Frame Material ID 0x2 Byte 0x1 Flip Type 0x3 Byte 0x1 Padding

Below is a table of possible material flip types. ^{(From Mario Kart Wii Wiki)}

Type	Description
0	None
1	Flip (Horizontal)
2	Flip (Vertical)
3	Rotate 90 Degrees
4	Rotate 180 Degrees
5	Rotate 270 Degrees

bnd1 (Bounding 1)

Same data structure as Panes, but used to limit interaction with buttons.

Offset	Size	Type	Description
0x00	0x4	String	Signature (bnd1)
0x04	0x4	UInt32	Section size (including the texture coordinates)
Same as pan1 from 0x8 to 0x4c

pas1 (Pane Start 1)

Marks the start of a pane hierarchy, with the parent being the previous pane.

Offset	Size	Type	Description
0x00	0x4	String	Signature (pas1)
0x04	0x4	UInt32	Section Size

pae1 (Pane End 1)

Marks the end of a pane hierarchy.

Offset	Size	Type	Description
0x00	0x4	String	Signature (pae1)
0x04	0x4	UInt32	Section Size

grp1 (Group 1)

Starts a pane group, which can be inside other pane groups.

Offset	Size	Type	Description
0x00	0x4	String	Signature (grp1)
0x04	0x4	UInt32	Section Size
0x08	0x10	String	Group Name
0x18	0x4	UInt32	Nr Pane References (=N)
0x1C	0x10 * N	String[N]	Pane References

grs1 (Group Start 1)

Starts a group hierarchy.

Offset	Size	Type	Description
0x00	0x4	String	Signature (grs1)
0x04	0x4	UInt32	Section Size

gre1 (Group End 1)

Ends a group hierarchy.

Offset	Size	Type	Description
0x00	0x4	String	Signature (gre1)
0x04	0x4	UInt32	Section Size

usd1 (User Data 1)

Contains a dictionary with strings as keys and variable values

Offset	Size	Type	Description
0x00	0x4	String	Signature (usd1)
0x04	0x4	UInt32	Section Size
0x08	0x4	UInt32	Number of entries (= N)
0xC	0xC * N // Variable	Entries[]	Entries

User Entries

Where an entry is as follows:

Offset	Size	Type	Description
0x0	0x4	UInt32	Key offset (from start of this entry) to null-terminated ascii string that serves as key.
0x4	0x4	UInt32	Value offset (from start of this entry).
0x8	0x2	UInt16	Number of entries or string length.
0xA	0x2	UInt16	Value type Value Type 0x0 String 0x1 Int 0x2 Float

Tools

• Every File Explorer and Switch Toolbox both have limited support for viewing these.
• Clypo allows exporting these files to yml and importing back to bclyt but it only supports scale, size, translation and rotation of panes.

See also

https://wiki.tockdom.com/wiki/BRLYT_(File_Format)
http://florian.nouwt.com/wiki/index.php/CLYT_%28File_Format%29 (Archived)
https://github.com/Gericom/EveryFileExplorer/tree/master/3DS/NintendoWare/LYT1
https://github.com/KillzXGaming/Switch-Toolbox/tree/master/File_Format_Library/FileFormats/Layout/CTR/Panes