[Solved] Error: Variable not set before reading it

[Silverfire]

Hi all, thanks in advance for the help.

Running GM Studio 1.4, I have obj_waterfall which is an invisible object that creates water objects every few steps.

Instance Creation Code (set in Room window):

endpoint=416

Create event:

trigger=0

End Step event:

trigger+=abs(global.time)
if trigger>6 {alarm[0]=1 trigger=0}

Alarm 0 event:

with instance_create(x+random(64)-32,y,obj_water) {start=y kill=endpoint}

global.time is a variable that can range between -3 and 3 that can be changed at any time by another object and that affects the rate at which obj_water instances appear, that's why I run an End Step instead of using an alarm that resets itself every few steps.

obj_water code:
End Step event:

if y>kill or y<start instance_destroy()
vspeed=global.time*8

I get the following error when running the game:

FATAL ERROR in
action number 1
of Alarm Event for alarm 0
for object obj_waterfall:

Variable obj_water.endpoint(100007, -2147483648) not set before reading it.
 at gml_Object_obj_waterfall_ObjAlarm0_1 (line 1) - with instance_create(x+random(64)-32,y,obj_water) {start=y kill=endpoint}

I'm not sure why I get this error. endpoint is set in the room creation code for obj_waterfall and obj_water is not supposed to have an endpoint variable, but its kill variable should be set to its obj_waterfall spawner's endpoint value no? There will be multiple obj_waterfall instances in a room, so I don't think I can use a global.endpoint variable.

 

[jo-thijs]

That's a misleading title you've got there.

If I understand correctly what you're trying to do,
you should just simply change your occurences of "endpoint" to "global.endpoint".
You've currently made endpoint a variable local to the room creation code, so it doesn't exist for other instances.

 

[Silverfire]

Sorry title should be better now. Also, I meant the Instance Creation Code you set in the Room window, not the one in the Settings tab, my bad.

 

[Yal]

You define endpoint in the waterfall, not the water - so the waterfall has that variable, the water does not, because the water's variable is called kill. So change the code in the water to check for kill instead of endpoint.

 

[jo-thijs]

Sorry title should be better now. Also, I meant the Instance Creation Code you set in the Room window, not the one in the Settings tab, my bad.

Well, because you use the variable endpoint in a with structure, GameMaker thinks your refering to a variable of obj_water.
You can tell GameMaker that it's actually the variable of the instance that called the with structure by prefixing the "endpoint" with "other." inside the with structure.

 

[Silverfire]

Using the "other." prefix solved the issue, thanks!