Deleting Animations

[Mark]

I'm making a game. I need to maintain a bunch of objects, in this
case animations (explosions and stuff). I've decided to use an STL
vector. From my understanding, I need to declare it as
vector<Animatio n*so that I can insert new animations with something
like myAnimations.pu sh_back(new Animation(...)) ; So that's all fine
and dandy, but what I can't decide on is how to delete this animation
after it's done playing (the explosion should be deleted and removed
from the vector when it's done cycling through all it's frames). I've
been told it's a bad idea to get an object to delete itself, because
then the caller won't know whether or not it still exists, and it's
just a bad design decision. So, would it be best to have some sort of
boolean in my animation object that says something like
"animationCompl ete", and when set to true the iterator would then
remove it? If so, what would my iterator look like?

for( vector<Animatio n*>::iterator current = myAnimations.be gin();
current != myAnimations.en d(); current++ )
{
(*current)->step(); // tells the animation to change frames
and do whatever it needs to do
if( (*current)->animationCompl ete )
{
current = projectile.eras e(current);
delete (*current); // <-- is this right?
continue;
}
(*current)->draw(); // draw it
}

Code looks kind of ugly... is that really the best way of doing it?

[=?iso-8859-1?q?Erik_Wikstr=F6m?=]

On 27 Apr, 05:53, Mark <mnbaya...@gmai l.comwrote:

I'm making a game. I need to maintain a bunch of objects, in this
case animations (explosions and stuff). I've decided to use an STL
vector. From my understanding, I need to declare it as
vector<Animatio n*so that I can insert new animations with something
like myAnimations.pu sh_back(new Animation(...)) ; So that's all fine
and dandy, but what I can't decide on is how to delete this animation
after it's done playing (the explosion should be deleted and removed
from the vector when it's done cycling through all it's frames). I've
been told it's a bad idea to get an object to delete itself, because
then the caller won't know whether or not it still exists, and it's
just a bad design decision. So, would it be best to have some sort of
boolean in my animation object that says something like
"animationCompl ete", and when set to true the iterator would then
remove it? If so, what would my iterator look like?

for( vector<Animatio n*>::iterator current = myAnimations.be gin();
current != myAnimations.en d(); current++ )
{
(*current)->step(); // tells the animation to change frames
and do whatever it needs to do
if( (*current)->animationCompl ete )
{
current = projectile.eras e(current);
delete (*current); // <-- is this right?
continue;
}
(*current)->draw(); // draw it
}

Code looks kind of ugly... is that really the best way of doing it?

Is there any special reason why you don't just declare it as
vector<Animatio nand add new elements like this:
'myAnimations.p ush_back(Animat ion(...))', notice the lack of new?

Then all you have to do is to use erase() on the vector to delete
them, I think it's possible to add a predicate to erase so that it
only erases those where animationComple te is true.

--
Erik Wikström

[mos]

"Mark" <mn*******@gmai l.com>
??????:11****** *************** *@r3g2000prh.go oglegroups.com. ..

I'm making a game. I need to maintain a bunch of objects, in this
case animations (explosions and stuff). I've decided to use an STL
vector. From my understanding, I need to declare it as
vector<Animatio n*so that I can insert new animations with something
like myAnimations.pu sh_back(new Animation(...)) ; So that's all fine
and dandy, but what I can't decide on is how to delete this animation
after it's done playing (the explosion should be deleted and removed
from the vector when it's done cycling through all it's frames). I've
been told it's a bad idea to get an object to delete itself, because
then the caller won't know whether or not it still exists, and it's
just a bad design decision. So, would it be best to have some sort of
boolean in my animation object that says something like
"animationCompl ete", and when set to true the iterator would then
remove it? If so, what would my iterator look like?

for( vector<Animatio n*>::iterator current = myAnimations.be gin();
current != myAnimations.en d(); current++ )
{
(*current)->step(); // tells the animation to change frames
and do whatever it needs to do
if( (*current)->animationCompl ete )
{
current = projectile.eras e(current);
delete (*current); // <-- is this right?
continue;
}
(*current)->draw(); // draw it
}

Code looks kind of ugly... is that really the best way of doing it?

I suppose it should be :

delete (*current); // first
current = projectile.eras e(current); // second

and I almost use list as
for (it = list.begin(); it != list.end(); )
{
if ((*it).die())
{
delete *it;
it = list.erase(it)
}
else
++it;
}

[mos]

Hi
sorry for posting unfinished mail.
I mean you'd better choose list to do it than vector.

mos.

[Roland Pibinger]

On 26 Apr 2007 23:22:17 -0700, =?iso-8859-1?q?Erik_Wikstr =F6m?= wrote:

>Is there any special reason why you don't just declare it as
vector<Animati onand add new elements like this:
'myAnimations. push_back(Anima tion(...))', notice the lack of new?

I guess the reason simply is that he deosn't want to duplicate the
Animation objects. The reason why the original code looks so 'ugly' is
that STL was designed only for values, not for (pointers to) objects.
--
Roland Pibinger
"The best software is simple, elegant, and full of drama" - Grady Booch

[Jim Langston]

"Mark" <mn*******@gmai l.comwrote in message
news:11******** **************@ r3g2000prh.goog legroups.com...

I'm making a game. I need to maintain a bunch of objects, in this
case animations (explosions and stuff). I've decided to use an STL
vector. From my understanding, I need to declare it as
vector<Animatio n*so that I can insert new animations with something
like myAnimations.pu sh_back(new Animation(...)) ; So that's all fine
and dandy, but what I can't decide on is how to delete this animation
after it's done playing (the explosion should be deleted and removed
from the vector when it's done cycling through all it's frames). I've
been told it's a bad idea to get an object to delete itself, because
then the caller won't know whether or not it still exists, and it's
just a bad design decision. So, would it be best to have some sort of
boolean in my animation object that says something like
"animationCompl ete", and when set to true the iterator would then
remove it? If so, what would my iterator look like?

for( vector<Animatio n*>::iterator current = myAnimations.be gin();
current != myAnimations.en d(); current++ )
{
(*current)->step(); // tells the animation to change frames
and do whatever it needs to do
if( (*current)->animationCompl ete )
{
current = projectile.eras e(current);
delete (*current); // <-- is this right?
continue;
}
(*current)->draw(); // draw it
}

Code looks kind of ugly... is that really the best way of doing it?

The way I'm doing it:

// Update ALL the -On-The-Fly- or Fired 'Beams' to NEW positions.
for ( BeamEffectsType ::iterator it = Client.BeamEffe cts.begin(); it !=
Client.BeamEffe cts.end(); )
{
if ( !(*it).second->Update() )
{
delete (*it).second;
it = Client.BeamEffe cts.erase(it);
}
else
++it;
}

Although I'm using a map instead of a vector, the same logic should apply.

The only real difference between mine and yours is I have the function call
itself return a boolean. So you could have your step() return bool whether
to delete it or not. Also, your code is not removing the element from the
vector, which it needs to.

[=?iso-8859-1?q?Erik_Wikstr=F6m?=]

On 27 Apr, 11:23, rpbg...@yahoo.c om (Roland Pibinger) wrote:

On 26 Apr 2007 23:22:17 -0700, =?iso-8859-1?q?Erik_Wikstr =F6m?= wrote:

Is there any special reason why you don't just declare it as
vector<Animatio nand add new elements like this:
'myAnimations.p ush_back(Animat ion(...))', notice the lack of new?

I guess the reason simply is that he deosn't want to duplicate the
Animation objects. The reason why the original code looks so 'ugly' is
that STL was designed only for values, not for (pointers to) objects.

I asked since in his original post he said that he wanted to use it
like this:

myAnimations.pu sh_back(new Animation(...)) ;

notice that he creates the object in the push_back, in which case my
solution would be just as good (or better).

--
Erik Wikström

[Roland Pibinger]

On 27 Apr 2007 02:36:38 -0700, =?iso-8859-1?q?Erik_Wikstr =F6m?= wrote:

>I asked since in his original post he said that he wanted to use it
like this:

myAnimations.p ush_back(new Animation(...)) ;

notice that he creates the object in the push_back, in which case my
solution would be just as good (or better).

Not quite. Your solution copies the new Animation object into the
vector and may copy all other objects in the vector due to relocation.
The pointer solution never copies Animation objects, just pointers.
Moreover, since Animation seems to be an object in the OO sense it may
be semantically problematic to duplicate these objects, i.e. the copy
constructor probably should private.
--
Roland Pibinger
"The best software is simple, elegant, and full of drama" - Grady Booch

[dave_mikesell]

On Apr 26, 11:53 pm, Mark <mnbaya...@gmai l.comwrote:

I'm making a game. I need to maintain a bunch of objects, in this
case animations (explosions and stuff). I've decided to use an STL
vector. From my understanding, I need to declare it as
vector<Animatio n*so that I can insert new animations with something
like myAnimations.pu sh_back(new Animation(...)) ; So that's all fine
and dandy, but what I can't decide on is how to delete this animation
after it's done playing (the explosion should be deleted and removed
from the vector when it's done cycling through all it's frames).

Why? Do you only use the explosion once in the entire game? You're
going to need a Cray to run your game if you allocate/load/delete
animations every time you play them.

[Mark]

On Apr 26, 11:22 pm, Erik Wikström <eri...@student .chalmers.sewro te:

On 27 Apr, 05:53, Mark <mnbaya...@gmai l.comwrote:

I'm making a game. I need to maintain a bunch of objects, in this
case animations (explosions and stuff). I've decided to use an STL
vector. From my understanding, I need to declare it as
vector<Animatio n*so that I can insert new animations with something
like myAnimations.pu sh_back(new Animation(...)) ; So that's all fine
and dandy, but what I can't decide on is how to delete this animation
after it's done playing (the explosion should be deleted and removed
from the vector when it's done cycling through all it's frames). I've
been told it's a bad idea to get an object to delete itself, because
then the caller won't know whether or not it still exists, and it's
just a bad design decision. So, would it be best to have some sort of
boolean in my animation object that says something like
"animationCompl ete", and when set to true the iterator would then
remove it? If so, what would my iterator look like?

for( vector<Animatio n*>::iterator current = myAnimations.be gin();
current != myAnimations.en d(); current++ )
{
(*current)->step(); // tells the animation to change frames
and do whatever it needs to do
if( (*current)->animationCompl ete )
{
current = projectile.eras e(current);
delete (*current); // <-- is this right?
continue;
}
(*current)->draw(); // draw it
}

Code looks kind of ugly... is that really the best way of doing it?

Is there any special reason why you don't just declare it as
vector<Animatio nand add new elements like this:
'myAnimations.p ush_back(Animat ion(...))', notice the lack of new?

Then all you have to do is to use erase() on the vector to delete
them, I think it's possible to add a predicate to erase so that it
only erases those where animationComple te is true.

--
Erik Wikström

heh. I was just thinking about that, and I asked my friend if it was
possible, but he said it was necessary to use "new". Shows how much
he knows :)
This will help, thank you!