Avatar Appearance

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KBcaution.png Important: See this if you're looking for general Appearance Editor help for Viewer 2.1.

For a good introduction to the elements of 3D character graphics, including meshes, morphs, bones, rendering, quaternions, and more see Martin Garstenauer's thesis.

Appearance Components

SL Avatar has "wearables" plus "attachments" for static appearance, and "animations".


Wearables encompass both clothing and body parts – represent customizations of the basic avatar mesh via parameterized changes and textures.

Clothing can be taken off, but body parts cannot. Otherwise, they are similar.

Wearables are created by the viewer when appearance is edited and the results are saved; changed parts of appearance (clothing, bodyparts) are saved as new wearables which are uploaded as assets. There is no support for directly importing or exporting wearables.


An "attachment" is an object ("linked set of primitives") which is rooted in the scene graph on an attachment point on an avatar. They are otherwise the same as other objects in SL, and can contain and execute scripts, inventory, maintain state, etc.

Attachments are heavily used for hair, some parts of clothing (dresses, cuffs) and accessories (jewelery, weapons). Some avatars may use attachments to completely obscure the underlying humanoid avatar mesh.

Attachments are never serialized as files on the viewer, and there is no import/export support. Attachments are only transmitted to/from the viewer as ObjectUpdate messages which describe the constantly updating scene graph of the simulation. Attachments are created/modified using the "build" tools in the viewer; modifications are transmitted from the viewer to the simulator as editing messages. The simulator then broadcasts the changes to other users as ObjectUpdates. When an attachment is saved to inventory, the linked set of prims structure is serialized to a structure that includes script state.


Animations are BVH files (BioVision Heirarchical data), a format developed by Biovision, a motion capture services company. Animations can be added to a scripted object to be played (e.g. a "poseball"), or incorporated into a gesture (a sequence of actions including text, sounds and animations invoked manually or triggered by a keyword). However, animations are often thought of as parts of avatars when they are controlled by an attachment to alter the avatar's default animations.

One common case is as an "Animation Override" script. These are used along with creative animations to deform the skeleton. Sometimes these override only some of the default animations (e.g. directed attention), sometimes everything is overridden. For example, "tinies" are created by folding the skeleton's limbs back on themselves. Non-humanoid avatars often use "meatballs" animations that compress the avatar to such an extent that it can be hidden inside an attachment. See Avatar deformation for more information.

Animations can be created in third party tools (e.g. Poser, QAvimator) and uploaded via File > Upload Animation (L$10). The animation is added to the inventory, and can then be incorporated into a script or gesture.


  • AgentWearablesRequest
    • This is where it starts. The viewer asks the simulator what it is wearing, and an AgentWearablesUpdate packet is returned.
  • AgentWearablesUpdate
    • A mapping of wearable types to asset IDs and item IDs is returned to the client. There are currently 13 different wearable types and all 13 will always be returned in this packet. If your avatar is not wearing a wearable type the asset ID and item ID for that type will be null IDs (all zeros). The next step is to request an asset transfer for all of the non-null asset IDs and download the wearable assets.
  • AgentIsNowWearing
    • Like the AgentWearablesUpdate packet but in the other direction. The viewer sends a list of the 13 wearable types and their associated item IDs, or null if nothing is being worn in that wearable slot. This is typically sent right before AgentSetAppearance.
  • AgentSetAppearance
    • Serves two purposes, to tell the server how our avatar mesh is deformed (with visual parameters) and what textures we are wearing. There are currently 218 VisualParam blocks sent with each AgentSetAppearance describing everything from the color of the avatar eyes to the gender slider. A TextureEntry is also sent that uses the same TextureEntry format objects use, but each "face" is hard-coded to describe a particular texture. This may or may not include baked textures for the five different baked layers (head, upper, lower, eyes, and skirt).
    • The ParamValue fields do not have parameter IDs associated with them in the packet, as it's assumed all viewers have the same parameter map in the same sequence. The parameters are stored internally as a floating point integer, and are converted to a single byte by inputting the value along with minimum and maximum weights for that parameter to a conversion function.

Linden avatar definition file

The parameters affecting avatar appearance are defined in an XML file located in the executable at


and in the source code at


With a few exceptions


all of the other files in the same directory are referenced by avatar_lad.xml. These include the mesh files (.llm), the texture files (.tga) and the avatar_skeleton.xml file (see below).

genepool.xml contains parameter sets for wearable types WT_SHAPE, WT_SKIN, WT_HAIR, and WT_EYES for several archetypal avatar definitions. This file supported the Randomize feature in the appearance editor. The functionality was removed in viewer 1.23, but a vestigial copy of genepool.xml may still be present. You can see the current parameter set for your own avatar by invoking the debug menus (Ctrl-Alt-D) and selecting Client->Character->Character Tests->Appearance To XML. This will create a file

SecondLife\character\new archetype.xml

in the same format as genepool.xml.

The avatar definition file affects the appearances on your viewer only. Any change to the file will not affect how others see the avatars. You can set value_default="1" for "Express_Tongue_Out" to make the avatars on your viewer give you the raspberries, but no one else will notice.

The interesting thing is that this file defines parameters that can be used in animations.

File structure

<?xml version="1.0" encoding="US-ASCII" standalone="yes"?>

<linden_avatar version="1.0" wearable_definition_version="22">

<skeleton file_name="avatar_skeleton.xml">
<attachment_point id="1" group="6" name="Chest" joint="mChest"
position="0.15 0 -0.1" rotation="0 90 90" visible_in_first_person="true"
pie_slice="2" hud="true" max_attachment_offset="1.5" />
<param ... >
<bone name="mNeck" scale="0 0 .2" offset="0 0 .004" />

Sets of
<mesh type="hairMesh" lod="0" file_name="avatar_hair.llm"
min_pixel_width="320" min_pixel_area="0.1" >
<param ... >
<param_morph />
<volume_morph name="HEAD" scale="-0.008 -0.006 0.015"
pos="0.07 0 -0.07" />
<mesh type="hairMesh" lod="1" file_name="avatar_hair_1.llm"
min_pixel_width="160" min_pixel_area="0.1" reference="avatar_hair.llm">

<global_color name="skin_color">
<param ... >
<param_color operation="blend" >
<value color="252, 215, 200, 255" />

<layer_set body_region="head" width="512" height="512"
clear_alpha="false" alpha_tga_file="head_alpha.tga" >
<layer name="head bump definition" render_pass="bump"
global_color="hair_color" fixed_color="128,128,128,255"
write_all_channels="true" >
<texture local_texture="lower_jacket" local_texture_alpha_only="true" />
and if not fixed_color
<texture tga_file="bump_head_base.tga" file_is_mask="FALSE" />
<morph_mask morph_name="Displace_Loose_Upperbody" invert="FALSE" />
<param ... >
<param_alpha tga_file="bump_face_wrinkles.tga" skip_if_zero="true"
multiply_blend="false" domain="0" />
<param_color operation="multiply" >
<value color="0, 0, 0, 0" />

<param ... >
<driven id="628" min1="0.1" max1="0.5" max2="1" min2="1" />


where bold text indicates required tags or parameters, standard text indicates a tag that can occur zero or one time, italics indicates that the tag can be repeated zero or more times, and bold italics indicates that at least one is required but more are possible.

Note that the values shown for parameters here may not be consistent. They are shown only to indicate the value type.

Parameter detail

<param ... > is

<param id="32" group="1" name="Male_Skeleton"
value_min="0" value_max="1" value_default="0"
edit_group="shape_body" edit_group_order="1"
label="Skeleton" label_min="Female" label_max="Male"
wearable="shape" clothing_morph="true" sex="male" shared="1"
show_simple="true" simple_percent_min="40" simple_percent_max="100"
camera_distance="2.2" camera_elevation=".1" camera_angle="0" >

Parameters are parsed in LLViewerVisualParamInfo::parseXml and LLVisualParamInfo::parseXml and are used by LLViewerVisualParam and LLVisualParam respectively when LLVOAvatar::loadAvatar is called.

Fields parsed in LLVisualParamInfo are used to describe the meaning of the parameters.

id -- mID
name -- mName
default ""
group -- mGroup
default "0"
value_min -- mMinWeight
default 0.
value_max -- mMaxWeight
default 1.
value_default -- mDefaultWeight
default 0.
sex -- mSex
"both" SEX_BOTH
"male" SEX_MALE
"female" SEX_FEMALE
default SEX_BOTH
label -- mDisplayName
default is name
label_min -- mMinName
default is "Less"
label_max -- mMaxName
default is "More"
Used only by mesh params. Indicates that the param affects more than one mesh

Fields parsed in LLViewerVisualParamInfo describe the appearance of the entries on the Edit->Appearance editing panel.

wearable -- mWearableType
"shape" WT_SHAPE
"skin" WT_SKIN
"hair" WT_HAIR
"eyes" WT_EYES
"shirt" WT_SHIRT
"pants" WT_PANTS
"shoes" WT_SHOES
"socks" WT_SOCKS
"jacket" WT_JACKET
"gloves" WT_GLOVES
"undershirt" WT_UNDERSHIRT
"underpants" WT_UNDERPANTS
"skirt" WT_SKIRT
default WT_INVALID
edit_group -- mEditGroup
default ""
edit_group_order -- mEditGroupDisplayOrder
By default, value 0, parameters are displayed in the order in which they appear in the xml file. "edit_group_order" overriddes this.

Optional camera offsets from the current joint center. Used for generating "hints" (thumbnails).

camera_distance -- mCamDist
default 0.5
camera_angle -- mCamAngle
default 0.
camera_elevation -- mCamElevation
default 0.

show_simple -- mShowSimple 
value is ignored
default FALSE
simple_percent_min -- mSimpleMin 
value is ignored
default 0.
simple_percent_max -- mSimpleMax 
value is ignored
default 100.

Loading the file

The file is parsed in LLVOAvatar::initClass() primarily by calls to LLVOAvatarInfo. Both classes are defined in indra\newview\llvoavatar.h(.cpp). There is one method for each of the major XML nodes


This data is then used to create instances of LLVOAvatar in LLVOAvatar::loadAvatar() which invokes LLVOAvatar::loadSkeletonNode() and LLVOAvatar::loadMeshNodes().


The avatar visual parameters are divided into those that define the avatar's appearance and those that are used in animations. Theoretically, they all could be used for animations, but the animations would have to start and end at the settings defined for the avatar rather than at the default values.

The group field of the <param> tag identifies those that are directly set in Edit->Appearance and sent in AgentSetAppearance messages as VISUAL_PARAM_GROUP_TWEAKABLE. The rest are identified as VISUAL_PARAM_GROUP_ANIMATABLE, but this is a bit misleading because it includes all of the driven parameters defined in the <driver_parameters> stanza. These are set by the driver parameters which are themselves directly tweakable.

Those that are not directly or indirectly tweakable include the emotes

  • 300 Express_Closed_Mouth
  • 301 Express_Tongue_Out
  • 302 Express_Surprise_Emote
  • 303 Express_Wink_Emote
  • 304 Express_Embarrassed_Emote
  • 305 Express_Shrug_Emote
  • 306 Express_Kiss
  • 307 Express_Bored_Emote
  • 308 Express_Repulsed_Emote
  • 309 Express_Disdain
  • 310 Express_Afraid_Emote
  • 311 Express_Worry_Emote
  • 312 Express_Cry_Emote
  • 313 Express_Sad_Emote
  • 314 Express_Anger_Emote
  • 315 Express_Frown
  • 316 Express_Laugh_Emote
  • 317 Express_Toothsmile
  • 318 Express_Smile
  • 632 Express_Open_Mouth

the hand morphs

  • 101 Hands_Relaxed
  • 102 Hands_Point
  • 103 Hands_Fist
  • 666 Hands_Relaxed_L
  • 667 Hands_Point_L
  • 668 Hands_Fist_L
  • 669 Hands_Relaxed_R
  • 670 Hands_Point_R
  • 671 Hands_Fist_R
  • 672 Hands_Typing
  • 766 Hands_Salute_R
  • 791 Hands_Peace_R
  • 792 Hands_Spread_R

and blinking eyes

  • 58 Blink_Left
  • 59 Blink_Right

The remaining visual params include a few useful for animations

  • 51 Furrowed_Eyebrows
  • 53 Surprised_Eyebrows
  • 54 Worried_Eyebrows
  • 55 Frown_Mouth
  • 57 Smile_Mouth

and a couple that seem to have been abandoned

  • 41 Old
  • 128 Wrinkles

Linden skeleton definition file

The skeletal structure is defined in an XML file located in the executable at


and in the source code at


It is referenced through the avatar definition file (see above) and can be considered to be part of the avatar definition.

File structure

<?xml version="1.0" encoding="US-ASCII" standalone="yes"?>

<linden_skeleton version="1.0" num_bones="46" num_collision_volumes="19">

<bone name="mPelvis" pos="0.000 0.000 1.067" rot="0.000000 0.000000 0.000000"
scale="1.000 1.000 1.000" pivot="0.000000 0.000000 1.067015">
<collision_volume name="PELVIS" pos = "-0.01 0 -0.02"
rot="0.000000 8.00000 0.000000" scale="0.12 0.16 0.17"/>
<bone ...>


where bold text indicates required tags or parameters, standard text indicates a tag that can occur zero or one time, and italics indicates that the tag can be repeated zero or more times.

The <bone ...> tag above is to indicate that the structure is recursive.

The "46" for num_bones is actually a typo in the file. There are only 26 bones defined.

Loading the file

The file is parsed in LLVOAvatar::initClass() using LLVOAvatarSkeletonInfo::parseXml. Both classes are defined in indra\newview\llvoavatar.h(.cpp).

This data is then used to create instances of LLVOAvatar in LLVOAvatar::loadAvatar() which invokes LLVOAvatar::buildSkeleton(). A special-purpose "screen" joint named "mScreen" is also created.

Linden binary mesh file

Meshes are defined in binary files located in the executable at


and in the source code at


They are referenced through the avatar definition file (see above) and can be considered to be part of the avatar definition.

The morphName in the binary mesh file matches the name field of the visual params with <param_morph> tags in the <mesh> stanzas. There are a few morphs defined in the mesh files that are not used by the avatar definition file

  • Blink_Both
  • Fingernails_Long
  • Wide_Lips

There are two types of mesh files: the base mesh definition and the level of detail (LOD) mesh definition, which always references a base mesh definition file. LOD meshes are used to simplify the rendering when the avatar is distant from the camera. There are several LOD meshes with progressively decreasing resolution.

The vertex information referenced by the LOD meshes is stored at the beginning of the base mesh vertex information.

File structure

Base mesh

char[24] "Linden Binary Mesh 1.0"
U8 hasWeights
U8 hasDetailTexCoords
LLVector3 position
LLVector3 rotationAngles
U8 rotationOrder (ignored, set to 0)
LLVector3 scale
U16 numVertices
LLVector3[ numVertices ] baseCoords
LLVector3[ numVertices ] baseNormals
LLVector3[ numVertices ] baseBinormals
LLVector2[ numVertices ] texCoords
if (hasDetailTexCoords)
LLVector2[ numVertices ] detailTexCoords
if (hasWeights)
F32[ numVertices ] weights
U16 numFaces
struct faces[ numFaces ]
S16[3] face
if ( hasWeights )
U16 numSkinJoints
struct skinJoints[ numSkinJoints ]
char[64] jointName
struct morph []
char[64] morphName
S32 numVertices
struct vertices[ numVertices ]
U32 vertexIndex
LLVector3 coord
LLVector3 normal
LLVector3 binormal
LLVector2 texCoord
char[64] "End Morphs"
S32 numRemaps (or EOF)
struct vertexRemap[ numRemaps ]
S32 remapSource
S32 remapDestination

where standart morphName for avatar_upper_body.llm is:

Big_Belly_Torso, Big_Chest, Breast_Female_Cleavage, Breast_Gravity, Chest_Male_No_Pecs, Displace_Loose_Upperbody, Fat_Torso, Fingernails_Long, Hands_Fist, Hands_Fist_L, Hands_Fist_R, Hands_Peace_R, Hands_Point, Hands_Point_L, Hands_Point_R, Hands_Relaxed, Hands_Relaxed_L, Hands_Relaxed_R, Hands_Salute_R, Hands_Spread_R, Hands_Typing, Love_Handles, Male_Torso, Muscular_Torso, No_Chest, Scrawny_Torso, Scrawny_Torso_Male, Shirtsleeve_flair, Small_Chest, default_upperbodyParallel

and standart morphName for avatar_lower_body.llm is:

Big_Belly_Legs, Big_Butt_Legs, Bowed_Legs, Displace_Loose_Lowerbody, Fat_Legs, Foot_Size, Leg_Longcuffs, Leg_Pantflair, Low_Crotch, Male_Legs, Male_Package, Muscular_Legs, Saddlebags, Scrawny_Legs, Shoe_Heel_Height, Shoe_Heel_Point, Shoe_Heel_Thick, Shoe_Platform_Height, Shoe_Platform_Width, Shoe_Toe_Point, Shoe_Toe_Square, Shoe_Toe_Thick, Small_Butt, default_lowerbodyParallel

Level Of Detail (LOD) mesh

char[24] "Linden Binary Mesh 1.0"
U8 hasWeights
U8 hasDetailTexCoords
LLVector3 position
LLVector3 rotationAngles
U8 rotationOrder (ignored, set to 0)
LLVector3 scale
U16 numFaces
struct faces[ numFaces ]
S16[3] face

where LLVector2 and LLVector3 are 2 and 3 floats respectively, and all numbers are little endian. Integers are 8, 16, or 32 bits signed (S) or unsigned (U).

The LOD .llm files actually contain fields for (if hasWeights) numSkinJoints set to zero, char[64] "End Morphs", and numRemaps set to zero, but these are not read by the viewer.

Each weight actually contains two pieces of information. The number to the left of the decimal point is the index of the joint and also implicitly indexes to the following joint. The actual weight is to the right of the decimal point and interpolates between these two joints. The index is into an "expanded" list of joints, not just a linear array of the joints as defined in the skeleton file. In particular, any joint that has more than one child will be repeated in the list for each of its children.

Loading the file

This data is used to create instances of LLVOAvatar in LLVOAvatar::loadAvatar() through LLVOAvatar::loadMeshNodes, LLPolyMesh::getMesh, LLPolyMeshSharedData::loadMesh, and LLPolyMorphData::loadBinary. These are found in indra\newview\llvoavatar.h(.cpp), indra\newview\llpolymesh.h(.cpp), and indra\newview\llpolymorph.h(.cpp), and indra\llappearance\llpolymorph.h(cpp).

Linden wearable definition file

The format is used for client/server communication - wearable assets are downloaded to cache/uploaded on creation. No import/export ability currently exists, although wearables are manipulated as files both on the viewer and server.

Source References

  • newview/llwearable.h
    • enum EWearableType
  • newview/llwearable.cpp
    • LLWearable::importFile – parses assets when "worn" from inventory, after download to cache
    • LLWearable::exportFile – called by LLWearable::saveNewAsset when created, does upload to asset system
  • newview/llvoavatardefines.h
    • enum ETextureIndex

File Structure


  • The file is line-oriented. UNIX line endings (LF 0x0A) are expected.
  • File encoding for strings is implicitly UTF-8. No byte-order mark is allowed.
  • Whitespace is used as delimiters. Spaces (0x20) and tabs (0x09) are considered whitespace, and any number may be used.

The file consists of the following blocks, which must occur in the specified order:

  • Format/Version
  • Name
  • Description
  • Permissions
  • Sale Info
  • Wearable type
  • Parameters
  • Textures


The string LLWearable version followed by the version number (currently 22)


LLWearable version 22


A single line string, terminated with a UNIX newline (LF 0x0A). Maximum length is 2047 bytes, not counting the newline. Encoding is UTF-8. A blank line is used to indicate the absence of a name.


Space Cadet Shirt


A single line string, terminated with a UNIX newline (LF 0x0A). Maximum length is 2047 bytes, not counting the newline. Encoding is UTF-8. A blank line is used to indicate the absence of a description.


This is my awesome shirt!

Permissions block

  • First line: The token permissions followed by the permission block version 0
  • Second line: open brace {
  • A sequence of permission name/value pairs, each on its own line
  • Final line: close brace }

The permission name/value pairs are:

  • base_mask, with 8-digit hexadecimal value
  • owner_mask, with 8-digit hexadecimal value
  • group_mask, with 8-digit hexadecimal value
  • everyone_mask, with 8-digit hexadecimal value
  • next_owner_mask, with 8-digit hexadecimal value
  • creator_id, with agent UUID in hexadecimal 8-4-4-4-12 format
  • owner_id, with agent UUID in hexadecimal 8-4-4-4-12 format
  • last_owner_id, with agent UUID in hexadecimal 8-4-4-4-12 format
  • group_id, with group UUID in hexadecimal 8-4-4-4-12 format
  • group_owned, with 0 (false) or 1 (true) flag

If a name/value is missing, a default value is assumed. For maximum compatibility, everything should be explicitly specified except group_owned when false.

Flags are defined in llinventory/llpermissionsflags.h:

  • PERM_TRANSFER = 0x00002000
  • PERM_MODIFY = 0x00004000
  • PERM_COPY = 0x00008000
  • PERM_MOVE = 0x00080000

Common masks are:

  • PERM_NONE 0x00000000

And common values are:

  • no modify: PERM_ALL & ~PERM_MODIFY = 0x7fffbfff
  • no copy: PERM_ALL & ~PERM_COPY = 0x7fff7fff
  • no modify or copy: = 0x7fff3fff
  • no transfer: PERM_ALL & ~PERM_TRANSFER = 0x7fffdfff
  • no modify, no transfer = 0x7fff9fff


       permissions 0
               base_mask       7fffffff
               owner_mask      7fffffff
               group_mask      00000000
               everyone_mask   7fffbfff
               next_owner_mask 7fffffff
               creator_id      d929385f-41e3-4a34-a04e-f1fc39f24f12
               owner_id        ff9a71eb-7414-4bf8-866e-a70ddeb7c3cf
               last_owner_id   ff9a71eb-7414-4bf8-866e-a70ddeb7c3cf
               group_id        00000000-0000-0000-0000-000000000000

Sale Info block

  • First line: The token sale_info followed by the sale_info block version 0
  • Second line: open brace {
  • A sequence of sale info name/value pairs, each on its own line
  • Final line: close brace }

The sale info name/value pairs are:

  • sale_type: one of:
    • not - not for sale
    • orig - the original is purchased
    • copy - a copy is purchased
    • cntn - the content is purchased
  • sale_price - price in L$


       sale_info       0
               sale_type       not
               sale_price      10

Wearable Type

  • A single line with the token type followed by the wearable type as a decimal integer

The type is defined in the EWearableType enumeration in newview/llwearable.h:

  • Bodyparts
    • WT_SHAPE = 0
    • WT_SKIN = 1
    • WT_HAIR = 2
    • WT_EYES = 3
  • Clothing
    • WT_SHIRT = 4
    • WT_PANTS = 5
    • WT_SHOES = 6
    • WT_SOCKS = 7
    • WT_JACKET = 8
    • WT_GLOVES = 9
    • WT_UNDERSHIRT = 10
    • WT_UNDERPANTS = 11
    • WT_SKIRT = 12


type 4


  • A line with the token parameters followed by the number of parameter ID/value pairs as a decimal integer
  • A sequence of parameter/ID value pairs, each on its own line


parameters 10
781 1
800 .92
801 1
802 1
803 1
804 1
805 1
828 .18
840 0
868 .27


  • A line with the token textures followed by the number of texture index/ID pairs as a decimal integer
  • A sequence of texture index/ID pairs, each on its own line
    • Texture index is defined in the ETextureIndex enumeration in newview/llvoavatardefines.h
    • Texture ID is the texture's UUID in hexadecimal 8-4-4-4-12 format

Texture indexes:

  • TEX_HAIR = 4
  • TEX_HEAD_BAKED = 8 (* See below)
  • TEX_UPPER_BAKED = 9 (* See below)
  • TEX_LOWER_BAKED = 10 (* See below)
  • TEX_EYES_BAKED = 11 (* See below)
  • TEX_SKIRT = 18
  • TEX_SKIRT_BAKED = 19 (* See below)
  • TEX_HAIR_BAKED = 20 (* See below)

* When the avatar changes a wearable, the simulator requests that the viewer rebake the *_BAKED textures; these are then uploaded as new temporary assets to the system so that the individual assets do not need to be downloaded. The *_BAKED textures are not referenced by wearables.


textures 1
1 08115557-ad4d-09ed-6b39-2ffc1f2b58b2