SMD

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SMD has been superseded in Source and Source 2 by the DMX model format.

The SMD file format (short for StudioModel Data) stores 3D models in ASCII for analysis and compilation by studiomdl. SMD files are usually generated by an SMD export plug-in for a given model editor package like MilkShape.

Note:

• SMD files which are used for vertex animation or flex animation are usually given a VTA file extension. VTA files never have a triangles block.
• (in all games since ) SMD files can also use the SMA or PHYS file extensions.

Software

Aside from Source and GoldSrc, SMD is known to be used by Sauerbraten and third party tools for The Sims and Mount & Blade. It is also optionally used by the FTE IQM Tool, used to create skeletal IQM models used by various id Tech 2 and id Tech 3 source ports.

General notes

• X is north in SMD. Elsewhere in Source it is east.
• The format is carriage return sensitive: text editors should use CR (Mac) or CRLF (Windows) line terminators instead of just LF (Linux). Each command must be on a separate line. There should also be a single blank line at the end (and only the end) of the file.
• White space is the only delimiter: any combination of tabs and spaces can be used to separate values, and for this reason multiword names should be enclosed in "quotation marks".
  Bug:Avoid using tab. Its presence can crash studiomdl in very large SMDs.  [todo tested in?]
• Comments are not supported by GoldSrc studiomdl.
  For Source studiomdl, the following comment delimiters can be used (but are likely to be stripped by 3D modeling programs):
  • Stand-alone line comments start with // (double forward slash)
  • End-line comments start with # (hashtag) or ; (semicolon)

Types

Reference / Collision

A complete snapshot of the model, including one frame of animation to define the default pose. Collision meshes follow the same pattern.

header ↓

nodes ↓

skeleton ↓

triangles ↓

Animation

A single skeletal animation.

header ↓

nodes ↓

skeleton ↓

Vertex (only in )

A flex animation library. Usually has extension .vta.

header ↓

nodes ↓

skeleton ↓ (a "time <n>" header for each flex shape; no position data required)

vertexanimation ↓

Data blocks

Here are the components of an SMD file, considered in order:

Tip:Unless otherwise noted, all integer values begin at 0 and all floating point values are limited to six decimal places.

Header

Simply:

version 1

Todo: There are at least 3 versions; document their differences somewhere.

Nodes

A list of all the bones in the model.

Note:Bones without attached vertices will not be compiled.

Syntax

nodes

Starts the node block.

<int|ID> "<string|Bone Name>" <int|Parent ID>

A bone definition. Unique ID number (does not have to be sequential), name in quote marks and the parent bone's ID. Bones without parents (i.e. children of the world) have a Parent ID of -1.

Note:Studiomdl matches bones across SMDs by name. IDs are internal to each file.

end

Ends the data block.

Example

A root bone with one child:

nodes
0 "root" -1
1 "child" 0
end

Skeleton

Position data for each bone in each animation frame. In a reference SMD there is only one frame, which contains the model's default posture.

Note:There can only be one animation in each SMD.

Syntax

skeleton

Begins the skeleton block.

time <int>

Begins a new frame. Any range of numbers can be used, so long as they increase sequentially.

<int|bone ID> <float|PosX PosY PosZ> <float|RotX RotY RotZ>

A bone's position relative to its parent (give absolute values in the case of root bones).

• Pos is position in units relative to the parent bone.
• Rot is local Tait-Bryan angles, given in radians relative to the parent bone (90° = 1.570796 rad)

Note:In , the first frame must include all bones. After that, those which have not moved relative to their parent since the last frame can be omitted.
Doing this in resets the bone to its default position; all frames should have all bones.

Confirm:Default as in first frame, or default as in reference pose?

Tip:Converting from a local rotation matrix to Euler angles might require you to invert the rotation matrix before conversion.

end

Ends the data block.

Example

Bone 1 move two units along the Y axis, then back again:

skeleton
time 0
0	0 0 0	1.570796 0 0
1	1 0 0	0 0 0
time 1
1	1 2 0	0 0 0
time 2
1	1 0 0	0 0 0
end

Triangles

A triangle in a model is defined by three vertices. Included in each triangle is its UV co-ordinates and envelope weights.

Note:Source's triangles are one-sided. The active face is the one around which the vertices can be traced clockwise.

Syntax

triangles

Begins the triangle block.

<material () or texture ()>

Defines the start of a new triangle and the material to apply to it.

File extensions (anything after a ".") are ignored in Source, but must be be bmp in GoldSrc.

Do not enclose in quotes and do not include a path ($cdmaterials () or $cdtexture () will provide one).

Warning:In StudioMDL, any faces using a materials named "null.bmp", "null.tga", or "debug/debugempty" will be deleted!
This is not the case for StudioMDL; several vanilla models have materials named "null.bmp".

Note:In , this should not exceed 63 characters (including the file extension).

<int|Parent bone> <float|PosX PosY PosZ> <normal|NormX NormY NormZ> <float|U V> <int|links> <int|Bone ID> <float|Weight> [...]

Defines a vertex.

• Pos is in world units
• Norm is the vertex normal, dictating how sharp or smooth the geometry is shaded
• U and V are the vertex's UV map co-ordinates

The final three values are only supported by , where they are optional: they override <Parent bone> to define a series of weightmap links. Bone ID and Weight are repeated for each link. If the weights do not add up to 1, any remaining value is placed on <Parent bone>.

Note:For SMDs included with $lod, Studiomdl can determine a vertex's weight links by copying those of the closest reference mesh vertex.

Note:SMD version 3 supports up to 8 additional UV layers after additional links. Format <int|extra uvs> U1 V1 U2 V2 [...].
Nonetheless, the MDL formats used by both GoldSrc and Source only support a single set of UVs, except for CSGO, which uses a second set for $decaltexture.

end

Ends triangle block.

Example

A flat, two-sided square. The left edge envelopes bone 0 and the right edge envelopes bone 1, and the UV map is a simple square projection:

triangles
my_texture.bmp
0	0 0 0	0 0 1	0 1	1 0 1
0	0 -1 0	0 0 1	0 0	1 0 1
1	1 -1 0	0 0 1	1 0	1 1 1
my_texture.bmp
0	0 0 0	1 0 1	0 1	1 0 1
1	1 -1 0	1 0 1	1 0	1 1 1
1	1 0 0	1 0 1	1 1	1 1 1
my_texture.bmp
1	1 -1 0	0 0 1	1 0	1 1 1
0	0 -1 0	0 0 1	0 0	1 0 1
0	0 0 0	0 0 1	0 1	1 0 1
my_texture.bmp
1	1 0 0	1 0 1	1 1	1 1 1
1	1 -1 0	1 0 1	1 0	1 1 1
0	0 0 0	1 0 1	0 1	1 0 1
end

Vertexanimation

This article or section needs to be updated to include current information regarding the subject because:

This can also be used to store discrete key frames, using vertex animation instead of flex animation.

Remember to check for any notes left by the tagger at this article's talk page.

(only in Source) Position of vertices in various morph targets, for use in vertex animation or flex animation. While this block uses the same time keyword as skeleton ↑, each 'frame' is instead a discrete, static shape. Transitions between them are created on-demand by the engine.

Note:A nodes ↑ and a skeleton ↑ block are needed in each VTA. The skeleton block needs only contain a "time <n>" header for each flex shape.

Syntax

vertexanimation

Begins the vertex animation block.

time <int>

Begins a morph target. The first target must include all vertices on the mesh in their reference positions; subsequent targets should include only vertices that differ from the reference.

<int|ID> <float|PosX PosY PosZ> <normal|NormX NormY NormZ>

A vertex.

• ID is the position of the equivalent reference vertex in the triangles ↑ block
• Pos is in absolute world units
• Norm defines the direction from which the vertex receives the most light

end

Ends the data block.