Hello everyone. Im looking for the right solution on how to remove objects properly

im having the next situation:

i have vector of 6 objects and then elements gets removed at the run time and i need to have an access to the right elements(at run time )

and what happens instead of it?

I have element[0], elemnt[1], element[2], element[3].

At runtime what if some of these objects doesnt exist anymore? I need to access the right vectors(the ones that exist).

In very common order : 0, 1, 2 , 3.

Any simple idea how can i achieve that?

so my code in which iterator i equals 0 then 1 and so on no longer works if some of these elements gets destroyed at run time

you can use a linked list carefully, or what I prefer is just marking objects as removed but actually remove them when you don't work with that vector

also you should check was the object removed or not

marking them as removed? thanks i will try)

yes make a boolean flag indicating removal and skip that objects when iterating

and when iteration is done you should filter the entire vector

it's O(n)

i cant mark some element in vector just like that

need to use std::pair<std::vector, std::string> ? something like this?

definitely there is no need to use string

existence of the object is a part of the object

@trollingchar i dont iterate through all elements at a time

Why not use a hash-map of game-object ID to game-object? And then just remove by key.

i would try it but what trollchar suggested already helped)

what i did was:

I added bool flag to object and then when i remove objects i just delete only objects and dont erase vector elements(so it still has all elements along with removed ones). And when i update my class of objects i just do the checking like if (object->getFlag()==true) object->update() . No need to set false flag since i remove objects anyway

So it's roughly like a pool

@trollingchar i actually do iterate through all objects when updating them but i dont when i access them at runtime after some event triggered. I guess i was just looking for an issue in wrong place)

people often look in the wrong place

i guess i just could set removed objects to nullptr ?

is that possible?

how are you going to do that?

its not possible to set vector element to nullptr?

you need to know its index

i dont like the null pointer approach because boolean flag is named and explicit

if you forget why that null is here you're in trouble

what is 'o'?

local variable

pointer to object

@Tyyppi_77 with a hash set?

The indirection explicitly reminds you that you need to look up the element and it's might not be there anymore. Some languages even remind you that the looked-up element might not exist in the map on a type-system level (Like in Rust, the lookup is an Option<Value>)

I don't see a way to iterate through it when there is a possibility of it being changed while iterating

@trollingchar there s no way to get index from object pointer ?

You probably need to have some remove-set that you empty at end of every frame. (Ofc. you can make it a vector, no reason to have the overhead of a set)

I think we should know what you are trying to implement

I have a feeling that we solve the problem in the wrong direction

@trollingchar just some test. Some idea.

thanks you all for the help

= )

What I want is this image:

I have a render that if the z axis is screen facing has a wrong result (some faces are white filled) while if the z axis is in the opposite direction I have the desired result

Here is a picture in the middle that clearly show a white filled face that superimposes to the wireframe

If I debug with Spector.js both drawing command (the original mattdesl.github.io/webgl-wireframes/app and my test)

so, what can it be? anyone can give some hints?