TgF2_InsideBuilding cannot be set from a level file

[Moburma]

This is something that's caused confusion at least for me for some time. When peeps go inside a building during play, the Flag2 state TgF2_InsideBuilding is set. This then occludes their drawing, even when using no buildings mode (hold B). This seems a little buggy and dependent on what building they go into, but let's ignore that for now and assume it is working as a rule.

When peeps are added to a level file and placed inside a building, this flag is not set, at least not automatically. This is why it's generally possible to see people inside buildings all over the place in the game, it doesn't know they are meant to be inside (at least in terms of holding B, it does draw them behind the scenery correctly). The solution to this seems to be to update their Flag2 state in the level file to add the state manually. However, this doesn't seem to actually work. Setting TgF2_InsideBuilding (by making their flag2 value 0x20000000 hex or 536870912 in decimal) in the level file just gets ignored by the game, they start with Flag 2 set to 0 and are visible inside the building.

I guess where the plot thickens is if this was ever a supported feature or not. It's very rarely used in the game's files, a good test is m 0,49 as the zealot inside the target bunker has it set in the file but is visible (in-game he appears with flag2 of 0). It's not clear if this ever worked or it was just set that way as a left over for this one character.

Here's also a version of m 2,5 with an extra agent added in the bunker building the red headed agent walks through. This building definitely occludes correctly during normal play, and the agent is set with the flag, but he is visible and the game has set him back to a flag2 of 0:

https://easyupload.io/1b80p9

[mefistotelis]

During level load, the game introduces some fixes to the input data. For people, the changes are:

            if (p_thing->Type == TT_PERSON)
            {
                if (fmtver < 15)
                    // Causes invisible NPCs when non-zero
                    p_thing->Flag2 = 0; // <-- relevant
                p_thing->U.UPerson.Flag3 = 0;
                p_thing->Flag2 &= (TgF2_InsideBuilding|TgF2_ExistsOffMap); // <-- relevant
                if ((p_thing->Flag & TngF_Unkn02000000) != 0)
                {
                    p_thing->ThingOffset = p_thing - things;
                    remove_thing(new_thing);
                    delete_node(p_thing);
                    continue;
                }
                reset_person_frame(p_thing);
                init_person_thing(p_thing);
                p_thing->Flag |= TngF_Unkn0004;
                if (fmtver < 6)
                    p_thing->Flag |= TngF_Unkn04000000;
                if (fmtver < 12)
                    sanitize_cybmods_fmtver11_flags(&p_thing->U.UPerson.UMod);
            }

So, in format versions >= 15, the TgF2_InsideBuilding and TgF2_ExistsOffMap flags are honored.

[Moburma]

So, in format versions >= 15, the TgF2_InsideBuilding and TgF2_ExistsOffMap flags are honored.

TgF2_ExistsOffMap definitely works fine, but TgF2_InsideBuilding just seems to get reset to 0. Here's the zealot in -m 0,49:

He's a) visible and b) Flag2 is 0

[mefistotelis]

Right, I see the flag disappearing. Curious. This does not happen during level load.

[mefistotelis]

Found it in level initialization:

    if ((p_person->Flag2 & TgF2_ExistsOffMap) != 0)
        delete_node(p_person);
    else
        p_person->Flag2 &= ~TgF2_InsideBuilding;

So it looks like TgF2_InsideBuilding is only honored if TgF2_ExistsOffMap is also set.
Why it's like that - I don't know. Maybe there is a reason, maybe not.

So if you place the thing with ExistsOffMap and then PING it into existence, it should be treated as within building.

[Moburma]

So if you place the thing with ExistsOffMap and then PING it into existence, it should be treated as within building.

Unfortunately that's the least useful combination - you'd nearly always do this just to ambush the player, so you wouldn't care about the building state. The whole thing is odd, I wonder if they actually DID want people visible inside buildings, if only so the player can see important targets in them. It's obviously totally inconsistent as a result, a large percentage of enemies in buildings are always visible, unless they walked in there in which case they are not...

[mefistotelis]

Unfortunately that's the least useful combination

I don't think I follow.

With the current implementation, there are two options for getting a person within a building:

1. Place the person outside building, and command it to go in at mission start. Then continue with the normal ambush commands.
2. Place the person inside building, but pinged out, and ping it in at mission start. Then continue with the normal ambush commands.

What is the issue with these?

[Moburma]

I guess it comes down to are peeps supposed to be visible inside buildings or not? The game itself is contradictory on this. If someone walks inside a building they are not visible. Taking this as the standpoint, then it follows people starting off placed in buildings should also always not be visible. Taking this as the intention means that TgF2_InsideBuilding should work from the level file as all peeps inside buildings must be hidden and that's the only way to do it if they start there. This would be a massively common use case throughout most levels of the game.

Unfortunately it's the opposite, you can't make them hidden at all!

In the end it just comes down to what their intention for this was, and that's not clear at all. It would make more sense to never hide peeps in buildings, but they clearly put effort making it so they do disappear.

EDIT:

Another contradiction - banks have transparent windows so you can see people inside them. Yet if someone walks inside, they are hidden!

[mefistotelis]

I guess it comes down to are peeps supposed to be visible inside buildings or not? The game itself is contradictory on this.

The game provides you with methods to make a person invisible in building. The game doesn't want you to place people there from start, due to technical limitations:

• Setting the flag while crossing a door may come in pair with other state changes, and using just the flag may cause further inconsistencies. I don't think it's the case in final, but am not sure. Maybe doors are counting people in? Maybe the person has building index stored somewhere?
• Verification of correctness of the flag is complex and computationally expensive - there is no function within the game to check if a person is surrounded by walls of a building.

The rule is: after crossing a door to a building, the person turns its visibility on or off.

EDIT: The transparent windows are curious though. Maybe the original idea was to keep them visible, and this changed due to GFX glitches caused by simplifications of the software rendering.