Lua Animation Event system for SNPCs

AE_INVALID = -1
AE_EMPTY = 0
AE_NPC_LEFTFOOT = 1
AE_NPC_RIGHTFOOT = 2
AE_NPC_BODYDROP_LIGHT = 3
AE_NPC_BODYDROP_HEAVY = 4
AE_NPC_SWISHSOUND = 5
AE_NPC_180TURN = 6
AE_NPC_ITEM_PICKUP = 7
AE_NPC_WEAPON_DROP = 8
AE_NPC_WEAPON_SET_SEQUENCE_NAME = 9
AE_NPC_WEAPON_SET_SEQUENCE_NUMBER = 10
AE_NPC_WEAPON_SET_ACTIVITY = 11
AE_NPC_HOLSTER = 12
AE_NPC_DRAW = 13
AE_NPC_WEAPON_FIRE = 14
AE_CL_PLAYSOUND = 15
AE_SV_PLAYSOUND = 16
AE_CL_STOPSOUND = 17
AE_START_SCRIPTED_EFFECT = 18
AE_STOP_SCRIPTED_EFFECT = 19
AE_CLIENT_EFFECT_ATTACH = 20
AE_MUZZLEFLASH = 21
AE_NPC_MUZZLEFLASH = 22
AE_THUMPER_THUMP = 23
AE_AMMOCRATE_PICKUP_AMMO = 24
AE_NPC_RAGDOLL = 25
AE_NPC_ADDGESTURE = 26
AE_NPC_RESTARTGESTURE = 27
AE_NPC_ATTACK_BROADCAST = 28
AE_NPC_HURT_INTERACTION_PARTNER = 29
AE_NPC_SET_INTERACTION_CANTDIE = 30
AE_SV_DUSTTRAIL = 31
AE_CL_CREATE_PARTICLE_EFFECT = 32
AE_RAGDOLL = 33
AE_CL_ENABLE_BODYGROUP = 34
AE_CL_DISABLE_BODYGROUP = 35
AE_CL_BODYGROUP_SET_VALUE = 36
AE_CL_BODYGROUP_SET_VALUE_CMODEL_WPN = 37
AE_WPN_PRIMARYATTACK = 38
AE_WPN_INCREMENTAMMO = 39
AE_WPN_HIDE = 40
AE_WPN_UNHIDE = 41
AE_WPN_PLAYWPNSOUND = 42
LAST_SHARED_ANIMEVENT = 43

local tbAnimationFrames = {
    ["idle"] = 35   -- Amount of frames this animation has
} -- Animations that aren't defined here, can't have animation events
local bFramesInitialized
function ENT:Initialize()
    -- default NPC initialization stuff (model has to be set here!)
    if(!bFramesInitialized) then    -- this is stupid, but I'm too tired to think of something better right now
        bFramesInitialized = true
        for seq, numFrames in pairs(tbAnimationFrames) do
            tbAnimationFrames[self:LookupSequence(seq)] = tbAnimationFrames[seq]
            tbAnimationFrames[seq] = nil
        end
    end
    self.m_tbAnimEvents = {}
    self.m_frameLast = -1
    self.m_seqLast = -1
    self:AddAnimationEvent(self:LookupSequence("idle"),35,AE_NPC_LEFTFOOT)  -- example animation event for a left footstep sound
end

function ENT:AddAnimationEvent(seq,frame,ev)    -- Sequence ID, target frame and animation event
    if(!tbAnimationFrames[seq]) then return end
    self.m_tbAnimEvents[seq] = self.m_tbAnimEvents[seq] || {}
    self.m_tbAnimEvents[seq][frame] = self.m_tbAnimEvents[seq][frame] || {}
    table.insert(self.m_tbAnimEvents[seq][frame],ev)
end

function ENT:Think()
    local seq = self:GetSequence()
    if(self.m_tbAnimEvents[seq]) then
        if(self.m_seqLast != seq) then self.m_seqLast = seq; self.m_frameLast = -1 end
        local frameNew = math.floor(self:GetCycle() *tbAnimationFrames[seq])    -- Despite what the wiki says, GetCycle doesn't return the frame, but a float between 0 and 1
        for frame = self.m_frameLast +1,frameNew do -- a loop, just in case the think function is too slow to catch all frame changes
            if(self.m_tbAnimEvents[seq][frame]) then
                for _, ev in ipairs(self.m_tbAnimEvents[seq][frame]) do
                    self:HandleAnimationEvent(ev)
                end
            end
        end
        self.m_frameLast = frameNew
    end
    self:NextThink(CurTime())
    return true
end

function ENT:HandleAnimationEvent(ev)
    if(ev == AE_NPC_LEFTFOOT) then self:EmitSound("npc/stalker/stalker_footstep_left" .. math.random(1,2) .. ".wav",75,100)
    elseif(ev == AE_NPC_RIGHTFOOT) then self:EmitSound("npc/stalker/stalker_footstep_right" .. math.random(1,2) .. ".wav",75,100)
    else -- other events
    end
end