Video: https://cdn.discordapp.com/attachments/366384007535001612/758487499517198366/2020-09-24_05-36-42.mp4

This PR adds a new event and 8 new functions:

onClientPedsProcessed 

This new event also fixes the issue with bone frame delay #465

bool setElementBonePosition (element theElement, int boneId, float x, float y, float z)
bool setElementBoneRotation (element theElement, int boneId, float yaw, float pitch, float roll)
float x, float y, float z getElementBonePosition (element theElement, int boneId)
float yaw, float pitch, float roll getElementBoneRotation (element theElement, int boneId)
bool setElementBoneMatrix (element theElement, int boneId, matrix theMatrix)
matrix getElementBoneMatrix (element theElement, int boneId) 
void updateElementRpHAnim(element theElement)

setElementBonePosition allows you to set the translation values for the bone.
setElementBoneRotation allows you to set the orientation values for the bone.
setElementBoneMatrix allows you to set the bone world matrix.

updateElementRpHAnim should be called after setElementBoneRotation. This is a bit heavy function, so it should be only called after you are completely done with rotating bones.

You can rotate a ped head vertically, like this:

local pitch = 0 
addEventHandler ( "onClientPedsProcessed", root,
function ()
 pitch = pitch + 3
 if pitch > 360 then pitch = 0 end
 local BONE_HEAD = 5
 setElementBoneRotation(localPlayer, BONE_HEAD, 0, pitch, 0)
 updateElementRpHAnim(localPlayer)
end)

BONE_NORMAL = 0 // Normal or Root both are same
BONE_PELVIS = 1
BONE_SPINE = 2
BONE_SPINE1 = 3
BONE_NECK = 4
BONE_HEAD = 5
BONE_L_BROW = 6
BONE_R_BROW = 7
BONE_JAW = 8
BONE_L_CLAVICLE = 31
BONE_L_UPPER_ARM = 32
BONE_L_FORE_ARM = 33
BONE_L_HAND = 34
BONE_L_FINGER = 35
BONE_L_FINGER_01 = 36
BONE_R_CLAVICLE = 21
BONE_R_UPPER_ARM = 22
BONE_R_FORE_ARM = 23
BONE_R_HAND = 24
BONE_R_FINGER = 25
BONE_R_FINGER_01 = 26
BONE_L_BREAST = 302
BONE_R_BREAST = 301
BONE_BELLY = 201
BONE_L_THIGH = 41
BONE_L_CALF = 42
BONE_L_FOOT = 43
BONE_L_TOE_0 = 44
BONE_R_THIGH = 51
BONE_R_CALF = 52
BONE_R_FOOT = 53
BONE_R_TOE_0 = 54

I am thinking of creating a new function to get LTMs (Local Transformation Matrix) of bones. This will make it easy for people to implement their own animation system that they use to animate their models from Lua. A shader can be used for matrix multiplication, and this will give a very good performance boost. GTA SA doesn't use a shader for skinning, and that's why multiple animating peds will cause FPS drop when they are streamed in. Adding an additional function to disable GTA SA skinning to save performance would also be nice since it's very slow as it relies on the CPU for skinning rather than the GPU. Nonetheless, it would be only useful for people who want to implement a custom skeletal animation system.