WoW:Detecting an instant cast spell: Difference between revisions

Unfortunately until more information is exposed to us through events or the API, there isn't currently a very reliable manner to catch instant cast spells being cast by the player, for interaction with the UI.  For a spell with a casting time, we get SPELLCAST_START with the spell name and the length of the cast time.  When the spell is finished (successfully) casting, we get a SPELLCAST_STOP.  In between we could get SPELLCAST_FAILED, SPELLCAST_INTERRUPTED, etc. which help us keep our states straight.

With an instant cast spell, we get one single SPELLCAST_STOP message, with no information (no spell name, no target, nothing).  As a result any mod that tries to track something involving these instant cast spells has to guess and play around.  I finished writing a Heal Tracking addon that me asures your healing efficiency, and for this purpose-- I needed those instant cast spells.  This is the method I used to get them reliably.

We have the following functions involved in the casting/targeting process:

Keep in mind when looking at this world, there are plenty of combinations that need to be considered when trying to detect instant cast spells.  I try to take these into consideration with my hooks.

This code will grab every spell that is being cast as well as every action that is being used on the client side.  Due to global cooldowns and other timing the overhead we incur here is very small, and I've done everything I can to make the code efficient and to ensure that the original functions are called as quickly as possible.

If you are interested in grabbing just a subset of instant cast functions, you can put them in a localized table and use that lookup to determine whether or not you change the MyMod_Spell variable.

As much as I wish it wasn't necessary, we need some way to glean the spell information.  This step is somewhat optional if you have your own tooltip to look this up, but I like my functions to be somewhat complete in providing accurate information.  Let's create a tooltip in our XML file so we can use it later.

  </GameTooltip>

We could use some variables here to store information as we progress, so we'll define the following in the LUA body:

  MyMod_Target = nil

  MyMod_oldCastSpell = CastSpell;

  CastSpell = MyMod_newCastSpell

Corrected syntax for 1.10 patch.

  CastSpellByName = MyMod_newCastSpellByName

  MyMod_oldUseAction = UseAction

  function MyMod_newUseAction(a1, a2, a3)

  UseAction = MyMod_newUseAction

This one is nice, and provides us with a good framwork because of its limitations.  Since SpellTargetUnit can ONLY be called after a spellcast has been issued, we can always be sure of who we're casting the spell on.  Even if ClearTarget is used, it just triggers the need to target after casting.

  SpellTargetUnit = MyMod_newSpellTargetUnit

This is the same code from SpellTargetUnit, with the names changed to protect the innocent.

  TargetUnit = MyMod_newTargetUnit

   

All we need to do here is clear MyMod_Spell to ensure we keep our state clean.

  SpellStopTargeting = MyMod_newSpellStopTargeting

After the 1.10 patch, CameraOrSelectOrMoveStart may no longer be hooked by custom UI mods.  The below code is preserved for historical purposes, but will no longer work.

  CameraOrSelectOrMoveStart = MyMod_newCameraOrSelectOrMoveStart

In the 1.10 patch, CameraOrSelectOrMoveStart can no longer be hooked by the user interface.  Attempting to call the hooked function will cause your addon to be reported as blocked by the game.  The solution to this problem is to hook the mouse click itself.  Since the user clicks on the screen to target a spell, all we have to do is add a call to our custom script when this occurs.

   

   function myMouseDown()

  end

In your OnLoad handler, register the following events: