Difference between revisions of "MDL file format (FSX)"
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==== LODT ==== | ==== LODT ==== | ||
− | + | This section defines the LOD table of the object. It is followed by a LODE section for each LOD level in the object. | |
==== LODE ==== | ==== LODE ==== |
Revision as of 12:35, 14 January 2007
This document describes the structure of FsX MDL files. This document is mainly useful for people who want to read or decode these MDL files in a tool.
Compared to the Fs2004 MDL format there are quite a few changes. One of the biggest is that aircraft and scenery MDL files now have the same format. At the moment the knowledge in this document mainly comes from evaluating simple scenery objects, so it is certainly not yet complete. If you have anything to add, please do so.
Contents
MDL sections
The MDL file uses the RIFF format, this means that the file consists of different sections. Each section starts with a four character label, followed by the size of the content in bytes (this size is thus without the length of the header itself). The tabel below shows how the different section can be nested.
Name | Description | Parent section |
RIFF | General RIFF section (covers entire file) | None |
MDLH | MDL header | RIFF |
MDLG | Object GUID | RIFF |
MDLN | Object friendly name | RIFF |
PARA | Parameters (?) | RIFF |
CRAS | Object crashbox | RIFF |
BBOX | Object boundingbox | RIFF |
RADI | Object radius | RIFF |
MDLD | Object data (?) | RIFF |
TEXT | Texture list | MDLD |
MATE | Material list | MDLD |
INDE | Triangle index list | MDLD |
VERB | Vertex buffer list | MDLD |
VERT | Vertex list | VERB |
TANS | Tangent list (?) | VERB |
TRAN | Static transformation matrices | MDLD |
AMAP | (?) | MDLD |
SCEN | Object scenegraph (?) | MDLD |
SGAL | Scenegraph ... (?) | MDLD |
SGVL | Scenegraph ... (?) | MDLD |
SGJC | Scenegraph ... (?) | MDLD |
SGBR | Scenegraph ... (?) | MDLD |
LODT | LOD table | MDLD |
LODE | External LOD (?) | LODT |
PART | Part list | LODE |
ANIB | (?) | MDLD |
The following subsection show more details about the content of these different sections.
MDLH
This the FS MDL object header. For FsX MDL objects it should contain the four characters MDLX as content.
MDLG
This section stores the object GUID. The GUID is stored in the following parts:
unsigned long data1 unsigned short data2 unsigned short data3 unsigned char data4[8]
In hexadecimal form the GUID is then written as:
{data1-data2-data3-data4[0:1]-data4[2:7]}
MDLN
This section contains a string with the friendly name of the object.
PARA
Unknown at the moment.
CRAS
This section stores the crashtree of the object. Exact details of the tree structure are still unknown (might be the same as the Fs2004 crashtree).
BBOX
This section stores the bounding box of the object in the following format:
float xmin float ymin float zmin float xmax float ymax float zmax
RADI
This section stores the radius of the object as a float.
MDLD
This section contains the actual data defining the object.
TEXT
This section contains the list of all textures of the object. Each texture is given as a 64 character string. Unlike the Fs2004 format no additional parameters are stored in the texture list, only the texture name.
MATE
This section contains a list of all materials of the object. Each material is defined by a 120 byte long record. The definition of this record is given below:
short material_type short (?) float (?) int texture_index; float (?) float (?) float (?) float (?) float (?) float (?) float base_color_R float base_color_G float base_color_B float base_color_A float specular_color_R float specular_color_G float specular_color_B float specular_color_A float specular_power float (?) float (?) float (?) float (?) float specular_bloom_floor float ambient_light_scale float (?) int source_blend int destination_blend int alpha_test_function float alpha_test_threshold float z_write_alpha
The material_type is 1 for materials without a texture and 3 for a materials that have a texture.
The source_blend and destination_blend parameters seem to use the following enumeration:
1 zero 2 once 3 srcColor 4 invSrcColor 5 srcAlpha 6 invSrcAlpha 7 destAlpha 8 invDestAlpha 9 destColor 10 invDestColor
The alpha_test_function parameter seems to use the following enumeration:
1 never 2 less 3 equal 4 lessEqual 5 greater 6 notEqual 7 greaterEqual 8 always
The z_write_alpha parameter has a value of 1 (float) when it is enabled (TRUE).
INDE
This section contains of a lot of triangles, each given by three short values. These values are the indices of the vertices to use. In the PART list an offset is specified for these indices, so the first vertex of a part seems to be zero always.
VERB
This section gives the vertex buffer of the object.
VERT
This section contains a list of all vertices of the object. Each vertex is given by a 32 byte record. The definition of this record is given below:
float position_x float position_y float position_z float normal_x float normal_y float normal_z float texture_mapping_x float texture_mapping_y
TANS
Unknown at the moment.
TRAN
Unknown at the moment.
AMAP
Unknown at the moment.
SCEN
Unknown at the moment.
SGAL
Unknown at the moment.
SGVL
Unknown at the moment.
SGJC
Unknown at the moment.
SGBR
Unknown at the moment.
LODT
This section defines the LOD table of the object. It is followed by a LODE section for each LOD level in the object.
LODE
Unknown at the moment.
PART
Unknown at the moment.
ANIB
Unknown at the moment.