Duplicate Animation Events Fix
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Note:This change is already present in the code generated using the "Start a Multiplayer mod from a template" option in the Create a Mod Wizard.Introduction
This is neither a prediction issue NOR a duplicated animation issue. It has to do with the introduction of the new PlayerAnimState code in the 15 June 2009 
Orange Box branch SDK release.
The addition of the PlayerAnimState brings great changes to controlling the animations on the player, but the problem is it was thrown into an already very messy animation code that involves literally hundreds of calls to functions in various levels of virtualization...
Explanation
At the end of the CHL2MPPlayerAnimState::DoAnimationEvent() function there is a little present from Valve, running a update to the View Model animation that corresponds to the third person animations. But, the problem lies in the way the SDK detects network variable changes, such as those pesky "
Parity" variables you might see around, specifically m_nResetEventsParity.
Let's backtrack a little, all weapons call their own viewmodel animations with a function called SendWeaponAnim() which does exactly what its name suggests and also increments m_nResetEventsParity.
Now the animation doesn't play twice because most weapon calls are in the same frame and it doesn't send the m_nNewSequenceParity since the sequence doesn't change. However, m_nResetEventsParity does get changed and it royally messes everything up.
Since the PlayerAnimState stuff is only invoked client side it changes the event parity (sometimes) before the server update changes it, this is an intermittent problem.
The code is actually used to call the animation events on the predicted viewmodels of OTHER players (so muzzle flashes and the like play properly in third person view). The problem is valve didn't filter it out for the local player which causes the "doubling" of animation events.
Requirements
- Using the latest OB SDK code
Solution
Simply add a filter for the local player in the following code hl2mp_playeranimstate.cpp:
In the function CHL2MPPlayerAnimState::DoAnimationEvent()
#ifdef CLIENT_DLL
// Make the weapon play the animation as well
if ( iGestureActivity != ACT_INVALID && GetBasePlayer() != C_BasePlayer::GetLocalPlayer() ) // <-- CHANGE HERE
{
CBaseCombatWeapon *pWeapon = GetHL2MPPlayer()->GetActiveWeapon();
if ( pWeapon )
{
pWeapon->EnsureCorrectRenderingModel();
pWeapon->SendWeaponAnim( iGestureActivity );
// Force animation events!
pWeapon->ResetEventsParity(); // reset event parity so the animation events will occur on the weapon.
pWeapon->DoAnimationEvents( pWeapon->GetModelPtr() );
}
}
#endif
Notes and Future Work
Future version of the SDK might fix this problem the other way, and that is to rely on this player animation code to setup the viewmodel animations instead of the weapon handling it's own animations in the specific parts of the code (PrimaryAttack, Draw, Holster, etc.)
