Difference between revisions of "Internal Animation Format"

Revision as of 07:59, 5 December 2009

From a programming perspective, there are several steps to uploading an animation from a BVH (BioVision Hierarchy) file:

Read and parse the BVH file, creating an LLKeyframeMotion object containing the motion data.
Gather input from the user (via the upload preview floater) for things like animation priority, facial expression, and looping; these settings are stored in the LLKeyframeMotion object.
Serialize the LLKeyframeMotion object as LLSD.
Upload the serialized data to the asset server.

Before other viewers can play an animation, they must:

Relevant source files:

The first part of the animation data is a header describing various details about the animation as a whole. The elements, in order, are:

field name	LLSD type	C++ type
version	integer	U16
sub_version	integer	U16
base_priority	integer	S32
duration	real	F32
emote_name	string	std::string
loop_in_point	real	F32
loop_out_point	real	F32
loop	integer	S32
ease_in_duration	real	F32
ease_out_duration	real	F32
hand_pose	integer	U32
num_joints	integer	U32

After the header is data for each joint in the skeleton:

field name	description	LLSD type	C++ type	Note
joint_name		string	std::string
joint_priority		integer	S32

At the start of the rotation data is the total number of rotation keys:

field name	description	LLSD type	C++ type	Note
num_rot_keys		integer	S32

Then, for each rotation key:

field name	LLSD type	C++ type
time	integer	U32
rot_angle_x	integer	U16
rot_angle_y	integer	U16
rot_angle_z	integer	U16

At the start of the position data is the total number of position keys:

field name	description	LLSD type	C++ type	Note
num_pos_keys		integer	S32

Then, for each position key:

field name	LLSD type	C++ type
time	integer	U32
pos_x	integer	U16
pos_y	integer	U16
pos_z	integer	U16

After the joint data are a number of entries for joint constraints. Constraints can target an avatar's parts in relation to each other or the ground.

field name	description	LLSD type	C++ type	Note
num_constraints		integer	S32

Then, for each joint constraint:

field name	LLSD type	C++ type	Note
chain_length	integer	U8	number of attached joints to include
constraint_type	integer	U8	0: point, 1: plane
source_volume	string	U8[16] array	skeleton collision volume name
source_offset	string (?)	LLVector3
target_volume	string	U8[16] array	skeleton collision volume name
target_offset	string (?)	LLVector3
target_dir	string (?)	LLVector3
ease_in_start	real	F32
ease_in_stop	real	F32
ease_out_start	real	F32
ease_out_stop	real	F32

@@ Line 83: / Line 83: @@
 ==Constraints==
-After the joint data are a number of entries for joint constraints (whatever that means):
+After the joint data are a number of entries for joint constraints. Constraints can target an avatar's parts in relation to each other or the ground.
 {|{{LLSD Field Table}}
@@ Line 92: / Line 92: @@
 {|{{LLSD Field Table}}
-{{LLSD Field Entry|name=chain_length|llsd=integer|cpp=U8}}
+{{LLSD Field Entry|name=chain_length|llsd=integer|cpp=U8|note=number of attached joints to include}}
-{{LLSD Field Entry|name=constraint_type|llsd=integer|cpp=U8}}
+{{LLSD Field Entry|name=constraint_type|llsd=integer|cpp=U8|note=0: point, 1: plane}}
-{{LLSD Field Entry|name=source_volume|llsd=uuid (?)|cpp=U8 array}}
+{{LLSD Field Entry|name=source_volume|llsd=string |cpp=U8[16] array|note=skeleton collision volume name}}
 {{LLSD Field Entry|name=source_offset|llsd=string (?)|cpp=LLVector3}}
-{{LLSD Field Entry|name=target_volume|llsd=uuid (?)|cpp= U8 array}}
+{{LLSD Field Entry|name=target_volume|llsd=string|cpp= U8[16] array|note=skeleton collision volume name}}
 {{LLSD Field Entry|name=target_offset|llsd=string (?)|cpp=LLVector3}}
 {{LLSD Field Entry|name=target_dir|llsd=string (?)|cpp=LLVector3}}