Difference between revisions of "JOE format"
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==Technical specification== | ==Technical specification== | ||
+ | "JOE" is a binary file format in which multi-byte values are expressed with the little-endian byte order. This section details version 3 of the file format. | ||
− | + | {{note|This documentation was generated by reverse engineering model.h and modle.cpp and inspecting the python blender export script. So there may be errors in evaluation.}} | |
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=== Data Type Map === | === Data Type Map === | ||
The following table explicitly defines the various data types used in a JOE file. | The following table explicitly defines the various data types used in a JOE file. | ||
− | {| | + | {| border="1" |
!Identifier!!Detailed Description | !Identifier!!Detailed Description | ||
|- | |- | ||
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This block of information initiates every file. | This block of information initiates every file. | ||
− | {| border="1 | + | {| border="1" |
!data type!!block offset!!name!!description | !data type!!block offset!!name!!description | ||
|- | |- | ||
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details a single configuration of a model. "File Header.num_frames" frames follow the file header. | details a single configuration of a model. "File Header.num_frames" frames follow the file header. | ||
− | {| border="1 | + | {| border="1" |
!data type!!block offset!!name!!description | !data type!!block offset!!name!!description | ||
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* num_textcoords Texture Coordinate blocks | * num_textcoords Texture Coordinate blocks | ||
− | === Face Format === | + | ===Face Format=== |
Each frame as "File Header.num_faces" face records immediately following the Frame header (decribed above). A face is basically several lists of indices in to vertex, normal, and text coord arrays described in following sections. | Each frame as "File Header.num_faces" face records immediately following the Frame header (decribed above). A face is basically several lists of indices in to vertex, normal, and text coord arrays described in following sections. | ||
For this version, a face is always a triangle ( i.e. a three-vertex polygon ). | For this version, a face is always a triangle ( i.e. a three-vertex polygon ). | ||
− | {| border="1 | + | {| border="1" |
!data type!!block offset!!name!!description | !data type!!block offset!!name!!description | ||
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|} | |} | ||
− | === Vertex Format === | + | ===Vertex Format=== |
A vertex block simply contains a three-element float array. Vertex blocks may have a misleading name because they are used for both vertices and normals. | A vertex block simply contains a three-element float array. Vertex blocks may have a misleading name because they are used for both vertices and normals. | ||
− | {| border="1 | + | {| border="1" |
!data type!!block offset!!name!!description | !data type!!block offset!!name!!description | ||
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|} | |} | ||
− | === Texture Coordinate Format === | + | ===Texture Coordinate Format=== |
A texture coordinate is a 2-dimensional coordinate used to map prtions of a texture to a model vertex. | A texture coordinate is a 2-dimensional coordinate used to map prtions of a texture to a model vertex. | ||
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!data type!!block offset!!name!!description | !data type!!block offset!!name!!description | ||
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[[Category:Files]] | [[Category:Files]] | ||
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Latest revision as of 02:33, 1 September 2012
This format is based on the md2 format but with a few enhanced features. It can be written to using a python export script for the Blender 3D modeling package.
Technical specification
"JOE" is a binary file format in which multi-byte values are expressed with the little-endian byte order. This section details version 3 of the file format.
Note: This documentation was generated by reverse engineering model.h and modle.cpp and inspecting the python blender export script. So there may be errors in evaluation. |
Data Type Map
The following table explicitly defines the various data types used in a JOE file.
Identifier | Detailed Description |
---|---|
int | 32-bit signed integer |
short | 16-bit signed integer |
short3 | Three consecutive shorts forming an array |
float | 32-bit floating-point value.
Unsure of the exact format... probably whatever is implemented by x86 machines. |
float3 | Three consecutive floats forming an array. |
File Header
This block of information initiates every file.
data type | block offset | name | description |
---|---|---|---|
int | 0 | magic | 8441211611(0x1F722AADB): number used to identify the file as a JOE file. Currently unchecked by vdrift. |
int | 4 | version | report the file version that this file conforms to. This specification details version 3 of the format. |
int | 8 | num_faces | every frame is expected to contain the same number of faces (polygons) this value specifies how many. This is currently limited to 32000. |
int | 12 | num_frames | Presumably, this details the number of frames used in an animation. Currently constrained to "1" |
Frame Format
details a single configuration of a model. "File Header.num_frames" frames follow the file header.
data type | block offset | name | description |
---|---|---|---|
int | 0 | num_verts | the number of vertices used in this frame |
int | 4 | num_textcoords | the number of texture coordinates used in this frame. |
int | 8 | num_normals | the number of vertex normals used in this frame. |
after each frame header, you will find
- File Header.num_faces Face blocks
- num_verts Vertex blocks
- num_normals Vertex blocks
- num_textcoords Texture Coordinate blocks
Face Format
Each frame as "File Header.num_faces" face records immediately following the Frame header (decribed above). A face is basically several lists of indices in to vertex, normal, and text coord arrays described in following sections.
For this version, a face is always a triangle ( i.e. a three-vertex polygon ).
data type | block offset | name | description |
---|---|---|---|
short3 | 0 | vertexIndex | Indeces in to the vertex array. These two constructs together define the location of each corner of the face in 3d space. |
short3 | 6 | normalIndex | Indeces in to the normals array. These two constructs help define how light sources interact with the face at each corner. Normals also help define which side of a face is "front". |
short3 | 12 | textureIndex | Indeces in to the texture coordinate array. These two constructs together help define which portions of a texture image map to each corner of the face. Note that in the future there may be a multiple of 3 entries in this array to accomidate applying many textures to a single face. Which images are used as textures by a particular model are defined by convention and explained in Car files and formats and Track files and formats |
Vertex Format
A vertex block simply contains a three-element float array. Vertex blocks may have a misleading name because they are used for both vertices and normals.
data type | block offset | name | description |
---|---|---|---|
float3 | 0 | vertex | A three-element float array defining the X, Y, and Z components of a vertex at offsets 0, 4, and 8 respectively |
Texture Coordinate Format
A texture coordinate is a 2-dimensional coordinate used to map prtions of a texture to a model vertex.
data type | block offset | name | description |
---|---|---|---|
float | 0 | u | a value between 0 and 1 indicating a position along the width of the texture |
float | 4 | v | a value between 0 and 1 indicating a position along the height of the texture. |