Explanation on this issue?

[Tyrande_ma3x]

I have a script that is supposed to issue usage of a specific item at some point of the game. Because there are a lot of items that I use based on instant, unit or point cast, I used a simplified method and just call the 3 natives instead of checking whether the item should be casted on units/points/instantaneously or not.

// This code is executed in a loop so I use an O(n) search in an array for item types. "crap" is an item variable, don't get confused... ^^
// ITEM[a] is my integer array containing all item types.
                        set crap = GetItemOfTypeFromUnitBJ(this.cast, ITEM[a])
                        if not UnitUseItemPoint(this.cast, crap, this.tx, this.ty) then
                            if not UnitUseItem(this.cast, crap) then
                            // should work?
                                if not UnitUseItemTarget(this.cast, crap, this.targ) then
                                    call BJDebugMsg("FAIL ?!?!?!?")
                                endif
                            endif
                        endif

Say this is a part of my script that issues that item casting. Everything works perfectly except for unit targeting... This event is supposed to trigger when a spell is cast and if the specific item targets units, it should target a unit. The problem is that the item was never used on the target even though I had no other mistakes in my code. After some toying around I rearranged the order of casting and found out that this time it works flawlessly.

// This code is executed in a loop so I use an O(n) search in an array for item types. "crap" is an item variable, don't get confused... ^^
                        set crap = GetItemOfTypeFromUnitBJ(this.cast, ITEM[a])
                        if not UnitUseItemPoint(this.cast, crap, this.tx, this.ty) then
                            if not UnitUseItemTarget(this.cast, crap, this.targ) then
                                if not UnitUseItem(this.cast, crap) then
                                    call BJDebugMsg("FAIL ?!?!?!?")
                                endif
                            endif
                        endif

So, can anybody explain to me why the first method does not work for unit targeting while the second works for everything?
Even though in the first method FAIL is never displayed, it does not cast the item!

 

[Tom Jones]

The obvious question is then how far the execution goes in the first code? Does UnitUseItem(...) return a strange boolean, just as IsUnitType(...)? Try comparing to false instead of using not, and try adding a debug message inside each if statement to see how far the code goes.

 

[Tyrande_ma3x]

In both situations FAIL never gets displayed (when it's a unit-target item) so it is returning TRUE... but there is no issued item casting.

//
                        set crap = GetItemOfTypeFromUnitBJ(this.cast, ITEM[a])
                        //if not UnitUseItemPoint(this.cast, crap, this.tx, this.ty) then
                            //if not UnitUseItemTarget(this.cast, crap, this.targ) then
                                //if not UnitUseItem(this.cast, crap) then
                        if UnitUseItemPoint(this.cast, crap, this.tx, this.ty) == false then
                            if UnitUseItem(this.cast, crap) == false then
                                if UnitUseItemTarget(this.cast, crap, this.targ) == false then
                                    call BJDebugMsg("FAIL ?!?!?!?")
                                endif
                            endif
                        endif

Totally same situation as with the not example... :nuts: Swapping UnitUseItem and UnitUseItemTarget works just fine.

 

[Rainther]

Confirm with debug messages which of the "if"s that makes it not reach "FAIL" and mentioned above. If you already have done it, you at least haven't said it.

 

[Tyrande_ma3x]

if UnitUseItem(this.cast, crap) == false then

After this part, UnitUseItemTarget does not get executed since UnitUseItem returns true and stops further actions... This is quite odd since UnitUseItem does not require any target and should return false, however even though it gives the unexpected result, it does not cast the item.
I also noticed something odd with those natives for point targeting items (only point since I use Channel with that option):

                        set crap = GetItemOfTypeFromUnitBJ(this.cast, ITEM[a])
                        if not UnitUseItemPoint(this.cast, crap, this.tx, this.ty) then
                            if not UnitUseItem(this.cast, crap) then
                            // should work?
                                if not UnitUseItemTarget(this.cast, crap, this.targ) then
                                    call BJDebugMsg("FAIL ?!?!?!?")
                                endif
                            endif
                        endif

FAIL gets displayed, although it shouldn't since UnitUseItemPoint is supposed to return true, right?

 

[Rainther]

Appeerntly there's something wrong with

set crap = GetItemOfTypeFromUnitBJ(this.cast, ITEM[a])
                        if not UnitUseItemPoint(this.cast, crap, this.tx, this.ty) then

since it indeed should return true

 

[Tom Jones]

I think it has something to do with range. If the target is out of range of the unit with the item it'll return false. This would make perfect sense because:

UnitUseItemPoint(...) - Has range.
UnitUseItemTarget(...) - Has range.
UnitUseItem(...) - Target is the unit itself, so no range.

I have an idea that UniUseItem(...) always will return true. I'll do some testing to see whether or not this is true.

*Edit*

Here's how I tested:

scope ItemTest initializer Init

globals
    private constant integer WHICH_ID   = 1     //Range 0-3.
    private constant real ITEM_RANGE    = 500
    private constant integer TARGET_ID  = 'hfoo'
    
    private unit U   
    private string array S
    private integer array ITEM_IDS  
    private unit array TARGET_UNITS
    private real array TARGET_POINTS
endglobals

private function onTest takes nothing returns nothing
    local item theitem = UnitAddItemById(U,ITEM_IDS[WHICH_ID])
    local integer i = 0
    local string s
    local boolean array b 
        
    loop
        exitwhen i == 2
        set b[i*3] = UnitUseItemPoint(U,theitem,TARGET_POINTS[i*2],TARGET_POINTS[i*2+1])
        set b[i*3+1] = UnitUseItemTarget(U,theitem,TARGET_UNITS<i>)
        set b[i*3+2] = UnitUseItem(U,theitem)
        set i = i+1
    endloop
    set i = 0
    loop
        exitwhen i == 6
        if i &lt; 3 then
            set s = &quot; within range = &quot;
        else
            set s = &quot; outside range = &quot;
        endif
        if b<i> then
            call BJDebugMsg(&quot;|cff00ff00&quot;+S[i-(i/3)*3]+s+&quot;true&quot;)
        else
            call BJDebugMsg(&quot;|cffff0000&quot;+S[i-(i/3)*3]+s+&quot;false&quot;)
        endif
        set i = i+1
    endloop
endfunction

private function Init takes nothing returns nothing
    local trigger trig = CreateTrigger()
    local integer i = 0
    local real r = ITEM_RANGE
    
    call TriggerRegisterTimerEvent(trig,1,false)
    call TriggerAddAction(trig,function onTest)
    
    set U = CreateUnit(Player(0),&#039;Hamg&#039;,0,0,0)
    call SetUnitInvulnerable(U,true)
    call UnitRemoveAbility(U,&#039;Aatk&#039;)
    
    loop
        exitwhen r &gt; 2*ITEM_RANGE
        set TARGET_UNITS<i> = CreateUnit(Player(1),TARGET_ID,r,0,0)
        set TARGET_POINTS[i*2] = (r/2)*(i+1)
        set TARGET_POINTS[i*2+1] = 0
        set r = r+ITEM_RANGE
        set i = i+1
    endloop
    
    set ITEM_IDS[0] = &#039;ssil&#039; //Point target item with cooldown.
    set ITEM_IDS[1] = &#039;wswd&#039; //Point target item without cooldown.
    set ITEM_IDS[2] = &#039;wlsd&#039; //Unit target item with cooldown.
    set ITEM_IDS[3] = &#039;wshs&#039; //Unit target item without cooldown.
    
    set S[0] = &quot;Point target&quot;
    set S[1] = &quot;Unit target&quot;
    set S[2] = &quot;No targer&quot;
    call FogModifierStart(CreateFogModifierRect(Player(0),FOG_OF_WAR_VISIBLE,GetWorldBounds(),true,false))
endfunction
endscope</i></i></i>

As I expected, UnitUseItem(...) will always return true, unless ofcourse the item is on cooldown.
UnitUseItemPoint(...) always returned false, even when using point targeted base items. I expect that this has something to do with a flaw in my test.
UnitUseItemTarget(...) works fine.
Range has to impact on the functions.

 

[Tyrande_ma3x]

> I expect that this has something to do with a flaw in my test.
In both my cases (the non-working and the working one) it returns false... Maybe a flaw in the native?
Good job for the tests, I will try to remember these things.