Block diagram
The MD2 format is used for 3D animated models in id Sofware's Quake II.
A model consists of named frames, each with the same number of vertices
(vertices_per_frame). Each such vertex has a position and normal in
model space. Each vertex has the same topological "meaning" across frames, in
terms of triangle and texture info; it just varies in position and normal for
animation purposes.
How the vertices form triangles is defined via disjoint triangles or via
gl_cmds (which allows strip and fan topology). Each triangle contains three
vertex_indices into frame vertices, and three tex_point_indices into
global tex_coords. Each texture point has pixel coords s_px and t_px
ranging from 0 to skin_{width,height}_px respectively, along with
{s,t}_normalized ranging from 0 to 1 for your convenience.
A GL command has a primitive type (TRIANGLE_FAN or TRIANGLE_STRIP) along
with some vertices. Each GL vertex contains tex_coords_normalized from 0
to 1, and a vertex_index into frame vertices.
A model may also contain skins, which are just file paths to PCX images.
However, this is empty for many models, in which case it is up to the client
(e.g. Q2PRO) to offer skins some other way (e.g. by similar filename in the
current directory).
There are 198 frames in total, partitioned into a fixed set of ranges used
for different animations. Each frame has a standard name for humans, but the
client just uses their index and the name can be arbitrary. The name, start
frame index and frame count of each animation can be looked up in the arrays
anim_names, anim_start_indices, and anim_num_frames respectively. This
information is summarized in the following table:
| INDEX | NAME | SUFFIX | NOTES |
|:--------:|--------:|:-------|:-------------------------------------------------------|
| 0-39 | stand | 01-40 | Idle animation |
| 40-45 | run | 1-6 | Full run cycle |
| 46-53 | attack | 1-8 | Shoot, reload; some weapons just repeat 1st few frames |
| 54-57 | pain1 | 01-04 | Q2Pro also uses this for switching weapons |
| 58-61 | pain2 | 01-04 | |
| 62-65 | pain3 | 01-04 | |
| 66-71 | jump | 1-6 | Starts at height and lands on feet |
| 72-83 | flip | 01-12 | Flipoff, i.e. middle finger |
| 84-94 | salute | 01-11 | |
| 95-111 | taunt | 01-17 | |
| 112-122 | wave | 01-11 | Q2Pro plays this backwards for a handgrenade toss |
| 123-134 | point | 01-12 | |
| 135-153 | crstnd | 01-19 | Idle while crouching |
| 154-159 | crwalk | 1-6 | |
| 160-168 | crattak | 1-9 | |
| 169-172 | crpain | 1-4 | |
| 173-177 | crdeath | 1-5 | |
| 178-183 | death1 | 01-06 | |
| 184-189 | death2 | 01-06 | |
| 190-197 | death3 | 01-08 | |
The above are filled in for player models; for the separate weapon models,
the final frame is 173 "g_view" (unknown purpose) since weapons aren't shown
during death animations. a_grenades.md2, the handgrenade weapon model, is
the same except that the wave frames are blank (according to the default
female model files). This is likely due to its dual use as a grenade throw
animation where this model must leave the player's model.
This page hosts a formal specification of Quake II player model (version 8) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: quake2_md2
title: Quake II player model (version 8)
application: Quake II
file-extension: md2
xref:
justsolve: MD2
tags:
- 3d
- game
license: CC0-1.0
endian: le
doc: |
The MD2 format is used for 3D animated models in id Sofware's Quake II.
A model consists of named `frames`, each with the same number of `vertices`
(`vertices_per_frame`). Each such vertex has a `position` and `normal` in
model space. Each vertex has the same topological "meaning" across frames, in
terms of triangle and texture info; it just varies in position and normal for
animation purposes.
How the vertices form triangles is defined via disjoint `triangles` or via
`gl_cmds` (which allows strip and fan topology). Each triangle contains three
`vertex_indices` into frame vertices, and three `tex_point_indices` into
global `tex_coords`. Each texture point has pixel coords `s_px` and `t_px`
ranging from 0 to `skin_{width,height}_px` respectively, along with
`{s,t}_normalized` ranging from 0 to 1 for your convenience.
A GL command has a `primitive` type (`TRIANGLE_FAN` or `TRIANGLE_STRIP`) along
with some `vertices`. Each GL vertex contains `tex_coords_normalized` from 0
to 1, and a `vertex_index` into frame vertices.
A model may also contain `skins`, which are just file paths to PCX images.
However, this is empty for many models, in which case it is up to the client
(e.g. Q2PRO) to offer skins some other way (e.g. by similar filename in the
current directory).
There are 198 `frames` in total, partitioned into a fixed set of ranges used
for different animations. Each frame has a standard `name` for humans, but the
client just uses their index and the name can be arbitrary. The name, start
frame index and frame count of each animation can be looked up in the arrays
`anim_names`, `anim_start_indices`, and `anim_num_frames` respectively. This
information is summarized in the following table:
```
| INDEX | NAME | SUFFIX | NOTES |
|:--------:|--------:|:-------|:-------------------------------------------------------|
| 0-39 | stand | 01-40 | Idle animation |
| 40-45 | run | 1-6 | Full run cycle |
| 46-53 | attack | 1-8 | Shoot, reload; some weapons just repeat 1st few frames |
| 54-57 | pain1 | 01-04 | Q2Pro also uses this for switching weapons |
| 58-61 | pain2 | 01-04 | |
| 62-65 | pain3 | 01-04 | |
| 66-71 | jump | 1-6 | Starts at height and lands on feet |
| 72-83 | flip | 01-12 | Flipoff, i.e. middle finger |
| 84-94 | salute | 01-11 | |
| 95-111 | taunt | 01-17 | |
| 112-122 | wave | 01-11 | Q2Pro plays this backwards for a handgrenade toss |
| 123-134 | point | 01-12 | |
| 135-153 | crstnd | 01-19 | Idle while crouching |
| 154-159 | crwalk | 1-6 | |
| 160-168 | crattak | 1-9 | |
| 169-172 | crpain | 1-4 | |
| 173-177 | crdeath | 1-5 | |
| 178-183 | death1 | 01-06 | |
| 184-189 | death2 | 01-06 | |
| 190-197 | death3 | 01-08 | |
```
The above are filled in for player models; for the separate weapon models,
the final frame is 173 "g_view" (unknown purpose) since weapons aren't shown
during death animations. `a_grenades.md2`, the handgrenade weapon model, is
the same except that the `wave` frames are blank (according to the default
female model files). This is likely due to its dual use as a grenade throw
animation where this model must leave the player's model.
doc-ref:
- https://icculus.org/~phaethon/q3a/formats/md2-schoenblum.html
- http://tfc.duke.free.fr/coding/md2-specs-en.html
- http://tastyspleen.net/~panjoo/downloads/quake2_model_frames.html
- http://wiki.polycount.com/wiki/OldSiteResourcesQuake2FramesList
seq:
- id: magic
contents: IDP2
- id: version
type: u4
valid: 8
- id: skin_width_px
type: u4
- id: skin_height_px
type: u4
- id: bytes_per_frame
type: u4
- id: num_skins
type: u4
- id: vertices_per_frame
type: u4
- id: num_tex_coords
type: u4
- id: num_triangles
type: u4
- id: num_gl_cmds
type: u4
- id: num_frames
type: u4
- id: ofs_skins
type: u4
- id: ofs_tex_coords
type: u4
- id: ofs_triangles
type: u4
- id: ofs_frames
type: u4
- id: ofs_gl_cmds
type: u4
- id: ofs_eof
type: u4
instances:
skins:
pos: ofs_skins
size: 64
type: strz
encoding: ascii
repeat: expr
repeat-expr: num_skins
tex_coords:
pos: ofs_tex_coords
type: tex_point
repeat: expr
repeat-expr: num_tex_coords
triangles:
pos: ofs_triangles
type: triangle
repeat: expr
repeat-expr: num_triangles
frames:
pos: ofs_frames
size: bytes_per_frame
type: frame
repeat: expr
repeat-expr: num_frames
gl_cmds:
pos: ofs_gl_cmds
# in http://tfc.duke.free.fr/coding/src/md2.c initially read as `int *`
# (a pool of `int`s) => hence `s4`
size: 4 * num_gl_cmds # FIXME: replace `4` with `sizeof<s4>` once `sizeof` is implemented for GraphViz
type: gl_cmds_list
anim_names:
value: |
['stand', 'run', 'attack', 'pain1', 'pain2', 'pain3', 'jump', 'flip',
'salute', 'taunt', 'wave', 'point', 'crstnd', 'crwalk', 'crattak',
'crpain', 'crdeath', 'death1', 'death2', 'death3']
anim_start_indices:
value: |
[0, 40, 46, 54, 58, 62, 66, 72,
84, 95, 112, 123, 135, 154, 160,
169, 173, 178, 184, 190]
anim_num_frames:
value: |
[40, 6, 8, 4, 4, 4, 6, 12,
11, 17, 11, 12, 19, 6, 9,
4, 5, 6, 6, 8]
anorms_table:
doc-ref: |
https://github.com/skullernet/q2pro/blob/f4faabd/src/common/math.c#L80
from Quake anorms.h
value: |
[
[-0.525731, 0.000000, 0.850651],
[-0.442863, 0.238856, 0.864188],
[-0.295242, 0.000000, 0.955423],
[-0.309017, 0.500000, 0.809017],
[-0.162460, 0.262866, 0.951056],
[0.000000, 0.000000, 1.000000],
[0.000000, 0.850651, 0.525731],
[-0.147621, 0.716567, 0.681718],
[0.147621, 0.716567, 0.681718],
[0.000000, 0.525731, 0.850651],
[0.309017, 0.500000, 0.809017],
[0.525731, 0.000000, 0.850651],
[0.295242, 0.000000, 0.955423],
[0.442863, 0.238856, 0.864188],
[0.162460, 0.262866, 0.951056],
[-0.681718, 0.147621, 0.716567],
[-0.809017, 0.309017, 0.500000],
[-0.587785, 0.425325, 0.688191],
[-0.850651, 0.525731, 0.000000],
[-0.864188, 0.442863, 0.238856],
[-0.716567, 0.681718, 0.147621],
[-0.688191, 0.587785, 0.425325],
[-0.500000, 0.809017, 0.309017],
[-0.238856, 0.864188, 0.442863],
[-0.425325, 0.688191, 0.587785],
[-0.716567, 0.681718, -0.147621],
[-0.500000, 0.809017, -0.309017],
[-0.525731, 0.850651, 0.000000],
[0.000000, 0.850651, -0.525731],
[-0.238856, 0.864188, -0.442863],
[0.000000, 0.955423, -0.295242],
[-0.262866, 0.951056, -0.162460],
[0.000000, 1.000000, 0.000000],
[0.000000, 0.955423, 0.295242],
[-0.262866, 0.951056, 0.162460],
[0.238856, 0.864188, 0.442863],
[0.262866, 0.951056, 0.162460],
[0.500000, 0.809017, 0.309017],
[0.238856, 0.864188, -0.442863],
[0.262866, 0.951056, -0.162460],
[0.500000, 0.809017, -0.309017],
[0.850651, 0.525731, 0.000000],
[0.716567, 0.681718, 0.147621],
[0.716567, 0.681718, -0.147621],
[0.525731, 0.850651, 0.000000],
[0.425325, 0.688191, 0.587785],
[0.864188, 0.442863, 0.238856],
[0.688191, 0.587785, 0.425325],
[0.809017, 0.309017, 0.500000],
[0.681718, 0.147621, 0.716567],
[0.587785, 0.425325, 0.688191],
[0.955423, 0.295242, 0.000000],
[1.000000, 0.000000, 0.000000],
[0.951056, 0.162460, 0.262866],
[0.850651, -0.525731, 0.000000],
[0.955423, -0.295242, 0.000000],
[0.864188, -0.442863, 0.238856],
[0.951056, -0.162460, 0.262866],
[0.809017, -0.309017, 0.500000],
[0.681718, -0.147621, 0.716567],
[0.850651, 0.000000, 0.525731],
[0.864188, 0.442863, -0.238856],
[0.809017, 0.309017, -0.500000],
[0.951056, 0.162460, -0.262866],
[0.525731, 0.000000, -0.850651],
[0.681718, 0.147621, -0.716567],
[0.681718, -0.147621, -0.716567],
[0.850651, 0.000000, -0.525731],
[0.809017, -0.309017, -0.500000],
[0.864188, -0.442863, -0.238856],
[0.951056, -0.162460, -0.262866],
[0.147621, 0.716567, -0.681718],
[0.309017, 0.500000, -0.809017],
[0.425325, 0.688191, -0.587785],
[0.442863, 0.238856, -0.864188],
[0.587785, 0.425325, -0.688191],
[0.688191, 0.587785, -0.425325],
[-0.147621, 0.716567, -0.681718],
[-0.309017, 0.500000, -0.809017],
[0.000000, 0.525731, -0.850651],
[-0.525731, 0.000000, -0.850651],
[-0.442863, 0.238856, -0.864188],
[-0.295242, 0.000000, -0.955423],
[-0.162460, 0.262866, -0.951056],
[0.000000, 0.000000, -1.000000],
[0.295242, 0.000000, -0.955423],
[0.162460, 0.262866, -0.951056],
[-0.442863, -0.238856, -0.864188],
[-0.309017, -0.500000, -0.809017],
[-0.162460, -0.262866, -0.951056],
[0.000000, -0.850651, -0.525731],
[-0.147621, -0.716567, -0.681718],
[0.147621, -0.716567, -0.681718],
[0.000000, -0.525731, -0.850651],
[0.309017, -0.500000, -0.809017],
[0.442863, -0.238856, -0.864188],
[0.162460, -0.262866, -0.951056],
[0.238856, -0.864188, -0.442863],
[0.500000, -0.809017, -0.309017],
[0.425325, -0.688191, -0.587785],
[0.716567, -0.681718, -0.147621],
[0.688191, -0.587785, -0.425325],
[0.587785, -0.425325, -0.688191],
[0.000000, -0.955423, -0.295242],
[0.000000, -1.000000, 0.000000],
[0.262866, -0.951056, -0.162460],
[0.000000, -0.850651, 0.525731],
[0.000000, -0.955423, 0.295242],
[0.238856, -0.864188, 0.442863],
[0.262866, -0.951056, 0.162460],
[0.500000, -0.809017, 0.309017],
[0.716567, -0.681718, 0.147621],
[0.525731, -0.850651, 0.000000],
[-0.238856, -0.864188, -0.442863],
[-0.500000, -0.809017, -0.309017],
[-0.262866, -0.951056, -0.162460],
[-0.850651, -0.525731, 0.000000],
[-0.716567, -0.681718, -0.147621],
[-0.716567, -0.681718, 0.147621],
[-0.525731, -0.850651, 0.000000],
[-0.500000, -0.809017, 0.309017],
[-0.238856, -0.864188, 0.442863],
[-0.262866, -0.951056, 0.162460],
[-0.864188, -0.442863, 0.238856],
[-0.809017, -0.309017, 0.500000],
[-0.688191, -0.587785, 0.425325],
[-0.681718, -0.147621, 0.716567],
[-0.442863, -0.238856, 0.864188],
[-0.587785, -0.425325, 0.688191],
[-0.309017, -0.500000, 0.809017],
[-0.147621, -0.716567, 0.681718],
[-0.425325, -0.688191, 0.587785],
[-0.162460, -0.262866, 0.951056],
[0.442863, -0.238856, 0.864188],
[0.162460, -0.262866, 0.951056],
[0.309017, -0.500000, 0.809017],
[0.147621, -0.716567, 0.681718],
[0.000000, -0.525731, 0.850651],
[0.425325, -0.688191, 0.587785],
[0.587785, -0.425325, 0.688191],
[0.688191, -0.587785, 0.425325],
[-0.955423, 0.295242, 0.000000],
[-0.951056, 0.162460, 0.262866],
[-1.000000, 0.000000, 0.000000],
[-0.850651, 0.000000, 0.525731],
[-0.955423, -0.295242, 0.000000],
[-0.951056, -0.162460, 0.262866],
[-0.864188, 0.442863, -0.238856],
[-0.951056, 0.162460, -0.262866],
[-0.809017, 0.309017, -0.500000],
[-0.864188, -0.442863, -0.238856],
[-0.951056, -0.162460, -0.262866],
[-0.809017, -0.309017, -0.500000],
[-0.681718, 0.147621, -0.716567],
[-0.681718, -0.147621, -0.716567],
[-0.850651, 0.000000, -0.525731],
[-0.688191, 0.587785, -0.425325],
[-0.587785, 0.425325, -0.688191],
[-0.425325, 0.688191, -0.587785],
[-0.425325, -0.688191, -0.587785],
[-0.587785, -0.425325, -0.688191],
[-0.688191, -0.587785, -0.425325],
]
types:
tex_point:
seq:
- id: s_px
type: u2
- id: t_px
type: u2
instances:
s_normalized:
value: (s_px + 0.0) / _root.skin_width_px
t_normalized:
value: (t_px + 0.0) / _root.skin_height_px
triangle:
seq:
- id: vertex_indices
type: u2
repeat: expr
repeat-expr: 3
doc: indices to `_root.frames[i].vertices` (for each frame with index `i`)
- id: tex_point_indices
type: u2
repeat: expr
repeat-expr: 3
doc: indices to `_root.tex_coords`
vec3f:
seq:
- id: x
type: f4
- id: y
type: f4
- id: z
type: f4
compressed_vec:
seq:
- id: x_compressed
type: u1
- id: y_compressed
type: u1
- id: z_compressed
type: u1
instances:
x:
value: x_compressed * _parent._parent.scale.x + _parent._parent.translate.x
y:
value: y_compressed * _parent._parent.scale.y + _parent._parent.translate.y
z:
value: z_compressed * _parent._parent.scale.z + _parent._parent.translate.z
vertex:
seq:
- id: position
type: compressed_vec
- id: normal_index
type: u1
instances:
normal:
value: _root.anorms_table[normal_index]
frame:
seq:
- id: scale
type: vec3f
- id: translate
type: vec3f
- id: name
size: 16
type: strz
encoding: ascii
- id: vertices
type: vertex
repeat: expr
repeat-expr: _root.vertices_per_frame
gl_cmds_list:
seq:
- id: items
type: gl_cmd
repeat: until
repeat-until: _.cmd_num_vertices == 0
if: not _io.eof
gl_cmd:
seq:
- id: cmd_num_vertices
type: s4
- id: vertices
type: gl_vertex
repeat: expr
repeat-expr: num_vertices
instances:
num_vertices:
value: 'cmd_num_vertices < 0 ? -cmd_num_vertices : cmd_num_vertices'
primitive:
value: 'cmd_num_vertices < 0 ? gl_primitive::triangle_fan : gl_primitive::triangle_strip'
gl_vertex:
seq:
- id: tex_coords_normalized
type: f4
repeat: expr
repeat-expr: 2
- id: vertex_index
type: u4
doc: index to `_root.frames[i].vertices` (for each frame with index `i`)
enums:
gl_primitive:
0: triangle_strip
1: triangle_fan