[ZScript] Assigning a PlayerPawn's UserCMD

[Gustavo6046]

I was trying to make the ζetaBot's movements compatible universally by assigning forwardMove, buttons, etc to an UserCmd struct and then assigning that struct (even if manually) to the possessed PlayerPawn's player.cmd.

What I may have figured out, is that apparently my struct is treated as a pointer when I assign it to a PlayerInfo, even if that PlayerInfo is a struct I declared in that function, along with the UserCmd; it's a Pointer< NativeStruct<UserCmd> >, but PlayerInfo wants a NativeStruct<UserCmd>.

The usual way - just plain assigning cmd to possessed.player.cmd - would not crash the compiler; it would crash the runtime, accessing a NULL pointer somewhere in the original C code. If this in qzdoom.pk3/zscript/shared/player.txt:

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native @UserCmd cmd;

isn't a pointer when I assign it to a PlayerInfo, why is it treated like such when assigning to its members?

I mean, I could just lazily copy parts of the player code for movement (TweakMove, etc), and make it work from such, but I don't want to, because it would be a bit redundant. Is there any other way? Preferably using UserCMDs?

[_mental_]

Instances of native structs are handled as pointers.
Notice the @ character before the type and check how UserCmd "objects" are used in core ZScript lumps.

As for the crash, post a runnable samples and I'll check what's wrong with it.

[Gustavo6046]

Thank you.

It's about ζetaBot, so it crashes if you press kp1 (summonfriend ZetaBot 0). I will updated the download link.

More specifically, the zscript.bot lump.

[_mental_]

GZDoom doesn't crash but shows you the following error

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VM execution aborted: tried to write to address zero.
Called from ZTBotController.uploadPlayerInfo at :zscript.bot, line 65
Called from ZTBotController.SetPossessed at :zscript.bot, line 181
Called from ZetaBot.PostBeginPlay at :zscript.bot, line 834

If you will add some debugging output to line 63, for example like this

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console.printf("pinfo == %p", pinfo);

you will figure out why it aborts with the error

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pinfo == 0000000000000000

This clearly shows that pinfo is null. Then how do you suppose GZDoom can access its members? It cannot and notifies you about the problem.

[Gustavo6046]

I knew there was something like that happening, but just doing another PlayerInfo and THEN assigning it would not work because it could not convert a NativeStruct pointer to instance, or whatever it was.

Either way, thanks for helping...

[_mental_]

The problem with your approach is attempt to work with objects that are not fully scriptable.
You cannot make fully functional player using ZScript only. GZDoom creates and manages players and their pawn classes from C++ code.
I suggest you to treat your bots as very advanced monsters instead of trying to fool the engine with a player imposter.

[Gustavo6046]

Okay then, thanks.

I have an idea for that - to emulate player movement as closely as possible, copying the TweakSpeeds thing (although I'd like to know how I would work with those functions). I'd also need to know how to use a custom weapon, to use its firing state, and who knows, better suggestions to rate them as well (the current approach is a bit limited).