PAC doesnt follow lag compensation in TTT

[Earu]

To reproduce this issue, have a player wear an outfit with model parts parented to any bone of a player. Hit the player while they are moving, notice how the part are desync'd.

[homonovus]

related source links
https://github.com/ValveSoftware/source-sdk-2013/blob/0d8dceea4310fde5706b3ce1c70609d72a38efdf/sp/src/game/server/player_lagcompensation.cpp#L410
https://github.com/ValveSoftware/source-sdk-2013/blob/0d8dceea4310fde5706b3ce1c70609d72a38efdf/sp/src/game/server/player_lagcompensation.cpp#L611

[CapsAdmin]

related garrysmod issue
Facepunch/garrysmod-issues#884

[wrefgtzweve]

If i understand the issue correctly whats shown in the video is what you mean right?
Did a test with this, seems like only GetBonePosition is affected while GetBoneMatrix + GetTranslation doesnt

gmod_erEwwfLhcl.mp4

The test code:

hook.Add( "HUDPaint", "BoneExample", function()
    for _, ply in ipairs( player.GetAll() ) do
        if not ply:Alive() then continue end
        if ply == LocalPlayer() then continue end

        local bone = ply:LookupBone( "ValveBiped.Bip01_Head1" )
        if not bone then continue end

        local matrix = ply:GetBoneMatrix( bone )
        if not matrix then continue end

        local pos = matrix:GetTranslation()
        local toScreen = pos:ToScreen()

        draw.SimpleText( "GetBoneMatrix", "DermaDefault", toScreen.x, toScreen.y, color_white, TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )

        local pos = ply:GetBonePosition( bone )
        local toScreen = pos:ToScreen()

        draw.SimpleText( "GetBonePosition", "DermaDefault", toScreen.x, toScreen.y, color_white, TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )
    end
end )

[TW1STaL1CKY]

Yeah, that is the problem. It looks like PAC does mainly use Entity:GetBoneMatrix, though there are a couple of spots still using Entity:GetBonePosition it seems. Those few instances are likely the cause

[CapsAdmin]

Last time I looked into this, I couldn't figure out how to use GetBoneMatrix without breaking the part placement of old outfits.