Two quick questions about actor flags

[Enjay]

The +SMASHABLE flag isn't explained in the Wiki. As far as I can see, in the original games, it's only used on the Hexen pottery items. I think all it does is make it so that if the item falls, when it hits the floor it gets damaged (to the point of destruction). The relevant code seems to be here. I think it unconditionally does enough damage to kill the actor, and it happens when the actor falls from any height - even a very small drop. Would that be correct?

[edit: for fun, I gave the cyberdemon the +SMASHABLE flag and, sure enough, if you summon one, he appears slightly above the floor, drops and then dies. Interestingly, he does not die if he walks down stairs under his own steam. However, if you push a Hexen pot off even a small step, it will fall and break.[/edit]
[edit2: I've also added the flag to the Actor flags page in the Wiki with my understanding of it, and added the ZScript definitions of the pottery items to their relevant pages because the Wiki only had their DECORATE ones and, for whatever reason, that didn't include the SMASHABLE flag. Sorry to anyone who keeps an eye on the Wiki, I kept making small typos and re-editing. I think it's OK now.
https://zdoom.org/wiki/Actor_flags#SMASHABLE
https://zdoom.org/wiki/Classes:Pottery1
https://zdoom.org/wiki/Classes:Pottery2
https://zdoom.org/wiki/Classes:Pottery3
[/edit]


The second question is about putting flags in the default block of a ZScript actor. I'm confused as to why it doesn't seem to matter whether you follow an actor flag with a ; or not.
+SOLID
and
+SOLID;
both seem to be acceptable, as does a list on one line like so
+SOLID +SHOOTABLE +NOBLOOD;
So, my question is really why does it not matter if an actor flag is followed by a ; or not, when omission of a ; in almost every other type of line is an error? Is there a "best practice" here - i.e. is it better to use a ; or not, or does it really not matter? (Hmmm... I guess technically that's three questions.)

[ZzZombo]

When a monster moves, it more or less teleports to the next spot in the chosen direction. That's why the monster in your test doesn't get killed from dropping off the stair step. Its vertical velocity remains 0, and the code you linked to only gets involved if the actor has negative vertical velocity.

[phantombeta]

The second question is about putting flags in the default block of a ZScript actor. I'm confused as to why it doesn't seem to matter whether you follow an actor flag with a ; or not.
+SOLID
and
+SOLID;
both seem to be acceptable, as does a list on one line like so
+SOLID +SHOOTABLE +NOBLOOD;
So, my question is really why does it not matter if an actor flag is followed by a ; or not, when omission of a ; in almost every other type of line is an error? Is there a "best practice" here - i.e. is it better to use a ; or not, or does it really not matter? (Hmmm... I guess technically that's three questions.)

It's by design. The other lines can have other things coming after them, so they need a delimiter that says with certainty "this thing ends at this point". (e.g., a property can be Height 10 or BloodType "Blood", "BloodSplatter", "AxeBlood")
Flags, on the other hand, can't have more things coming after them. They're always a + or - followed by a name, so there's no need for a delimiter, it already knows where to stop parsing the flag.

You can put semicolons after flags because you can actually just put "floating" semicolons anywhere in the default block
Like this:

Code: Select all

default {
    ; Height 50;;;;;;;
    ; ; ; ;
 ; ;+SHOOTABLE;
    ;
    ;
}

[Enjay]

When a monster moves, it more or less teleports to the next spot in the chosen direction.

Ah yes! That would certainly explain that. Thanks.

It's by design. The other lines can have other things coming after them...

That makes sense, thanks. So, all the ; I've been putting in hoping that I was being "more correct" were, if anything, less correct, though not actually harmful. I'd seen both in use (including inconsistencies in gzdoom.pk3) so I went with what looked like it should be the safest option.


Bonus question, purely out of interest, why is is when accessing a flag in ZSCript e.g. Wiki example...

Code: Select all

TNT1 A 0
{
  bShootable = true; // Sets the SHOOTABLE flag to true on the calling actor
  bVulnerable = false;  // Sets the VULNERABLE flag to false on the calling actor
}

"b" is used as the character before the flag? Does it have a precedent in some other language or something?

[phantombeta]

That makes sense, thanks. So, all the ; I've been putting in hoping that I was being "more correct" were, if anything, less correct, though not actually harmful. I'd seen both in use (including inconsistencies in gzdoom.pk3) so I went with what looked like it should be the safest option.

Neither is necessarily more correct than the other, it's really up to you whether you prefer to put semicolons after flags or not

Bonus question, purely out of interest, why is is when accessing a flag in ZSCript e.g. Wiki example...

Code: Select all

TNT1 A 0
{
  bShootable = true; // Sets the SHOOTABLE flag to true on the calling actor
  bVulnerable = false;  // Sets the VULNERABLE flag to false on the calling actor
}

"b" is used as the character before the flag? Does it have a precedent in some other language or something?

As is the case for a lot of other odd things about ZScript, this is yet another thing copied from UnrealScript
As for why UnrealScript does it like that, I believe it's because Unreal uses Hungarian notation for names, so the "b" would stand for "bool"/"boolean".
(This is also why if you look in GZDoom's C++ source code, you'll see the type names written as TArray, FName, AActor, etc.)

That said, it's an useful addition, it helps prevent flag names from clashing with variables and such defined in mods.

[Enjay]

Thank you. I figured there would be some reason. Coming from ZScript's inspiration (UnrealScript) makes sense.

And TIL about Hungarian notification too. Thanks.