Kingdom Hearts: Birth By Sleep - Models

Found inside PMP files or as raw PMO files, BBS stores it’s models in PMO blobs.

The format supports varying vertex types and has support for animation bones and two pass rendering.

PMO Header

Offset	Type	Description
0x0	uint32	Magic Value. Always “PMO\0” (0x004F4D50)
0x4	uint8	Number
0x5	uint8	Group
0x6	uint8	Version
0x7	uint8	Padding
0x8	uint8	Texture Count
0x9	uint8	Padding
0xA	uint16	Flag
0xC	uint32	Skeleton Offset
0x10	uint32	Mesh Offset 0
0x14	uint16	Triangle Count
0x16	uint16	Vertex Count
0x18	float	Model Scale
0x1C	uint32	Mesh Offset 1
0x20	float[4][8]	Bounding Box

Texture Info

The Header is followed by Texture Count Texture Info records

Offset	Type	Description
0x0	uint32	Offset of TM2 block if present in current file.
0x4	char[12]	Texture Name
0x10	float	Tiling Speed X
0x14	float	Tiling Speed Y
0x18	int32[2]	Padding

See also: TIM2

Mesh Sections

Mesh Offset 0 and Mesh Offset 1 both point to the start of a list of Mesh Section Headers. You keep reading headers + their verts until you encounter a 0 Vertex Count. This structure must be aligned on a 4 byte boundary.

Offset	Type	Description
0x0	uint16	Vertex Count
0x2	int8	Texture ID, an index into the list of Texture Info records
0x3	uint8	Vertex Size, in bytes
0x4	uint32	Vertex Flags, see below
0x8	uint8	Group
0x9	uint8	Triangle Strip count
0xA	uint16	Vertex Attribute
0xC	uint8[8]	List of bone indices that affect this section. Only present if the PMO blob contains a skeleton (ie: header.skeletonOffset != 0)
varies	uint32	Diffuse Color. Only present if vertexFlags.DiffuseColor & 1

The section header is followed by vertexCount * vertexSize bytes of vertex data. The next Section header follows on the next 4-byte alignment after that.

Vertex flags

The 24 least significant bits of this structure correspond to the PSP’s GE VTYPE command. The Primitive type bits correspond to the primitive type bits of the PSP’s GE PRIM command.

Bit	Count	Description
0	2	Texture Coordinate Format
2	3	Color Format
5	2	Normal Format (Not used by BBS)
7	2	Position Format
9	2	Weight Format
11	2	Indices Format (Not used by BBS)
13	1	Unused
14	3	Skinning Weights Count
17	1	Unused
18	3	Number of morphing weights (Not used by BBS)
21	2	Unused
23	1	Skip Transform Pipline (Not used by BBS)
24	1	Uniform Diffuse Flag
25	3	Unknown, possibly unused
28	4	Primitive Type

Coordinate Format

Texture Format, Normal Format, Position Format and Weight Format are as follows:

Value	Meaning
0x0	Not Present In Vertex
0x1	8-bit normalized
0x2	16-bit normalized
0x3	32-bit float

Weight format has only been observed to use 8-bit fixed in actual PMO blobs.

Color Format

Color Format is as follows:

Value	Meaning
0x0	Not Present In Vertex
0x4	16-bit BGR-5650
0x5	16-bit ABGR-5551
0x6	16-bit ABGR-4444
0x7	32-bit ABGR-8888

Only 32-bit ABGR-8888 has been observed in use by actual PMO blobs. If the Uniform Diffuse Flag is set, this value should be 0.

The number of skinning/morphing weights to be read is actually the value in the bit field + 1. If the weight format field is 0, these fields should be ignored.

Index Format has not been seen in actual PMO blobs, but if it is used the expected format is as follows:

Value	Meaning
0x0	Not using indices
0x1	8-bit
0x2	16-bit

Uniform Diffuse Flag indicates that all vertices in the section should use the same vertex color, which follows the header before the vertex data. See header structure above.

Primitive Type is as follows:

Value	Meaning
0x0	Points
0x1	Lines
0x2	Line Strips
0x3	Triangles
0x4	Triangle Strips
0x5	Triangle Fans
0x6	Sprites (Quads)

Only Triangles and Triangle Strips have been observed in actual PMO blobs.

Decoding Verts

Once the header has been read, along with any optional fields present, the vertex data immediatly follows. Each vertex follows the format described by the vertexFlags field. The vertex properties are written in the following order. Note that only position is mandatory.

Name
Joint Weights
Texture Coords
Color
Position

Reading ‘Normalized’ values

Vertex properties which are in the format 8-bit normalized or 16-bit normalized need to be converted to floating point values before rendering. Note that position values should read as signed values, the others as unsigned values. The conversion is as follows:

	// uint8
	float value = (float)data / 127.0f;
	// uint16
	float value = (float)data / 32767.0f;

Vertex Attribute

This field defines what kind of primitive is being rendered.

Value	Name	Meaning
0	ATTR_BLEND_NONE
1	ATTR_NOMATERIAL
2	ATTR_GLARE
4	ATTR_BACK
8	ATTR_DIVIDE
16	ATTR_TEXALPHA	Specifies that the texture used contains alpha values for transparency
24	FLAG_SHIFT
28	PRIM_SHIFT
32	ATTR_BLEND_SEMITRANS	Specifies that the material must be blended as semitransparent
64	ATTR_BLEND_ADD
96	ATTR_BLEND_SUB
224	ATTR_BLEND_MASK
256	ATTR_8
512	ATTR_9
1024	ATTR_DROPSHADOW
2048	ATTR_ENVMAP
4096	ATTR_12
8192	ATTR_13
16384	ATTR_14
32768	ATTR_15
16777216	FLAG_COLOR
33554432	FLAG_NOWEIGHT

Skeleton Header

Offset	Type	Description
0x0	uint32	Magic Value. Always “BON\0”
0x4	uint32	padding
0x8	uint16	Bone Count
0xA	uint16	padding
0xC	uint16	Skinned Bones
0xE	uint16	Skinned Bones Initial Index

Joint Definition

Offset	Type	Description
0x0	uint16	Bone Index
0x2	uint16	Padding
0x4	uint16	Parent Bone Index - 0xFFFF indicates no parent
0x6	uint16	Padding
0x8	uint16	Skinning Index
0xA	uint16	Padding
0xC	uint32	Padding
0x10	char[16]	Bone Name
0x20	Matrix4x4	Transform
0x60	Matrix4x4	Inverse Transform