Auto-incremented EntityPickup variants attempt to populate variant 0, which already has function in the base game

[Xalum]

I've recently been exploring using entity ID auto-incrementation to make my mods impossible to ID clash, however I have noticed something. When using variant auto-incrementation, regardless of entity type, the variant will auto-increment from 0. For most entity types this is a non-issue, however, entity 5.0.n has special behaviour used for spawning random pickups.

If you want to auto-increment pickup variants you have to first add a filler entry that absorbs variant 0, so that the rest of your entries can auto-increment safely. This isn't a huge issue, but it's something that may dissuade a newer modder away from using ID auto-incrementation, and is something that every mod that wants to use this feature will have to do. Populating the variant 0 pickup in the base game entities2.xml would alleviate this entirely.

[Zamiell]

For all other types, is using variant 0 okay? e.g. for familiars, tears, etc.?

[Xalum]

Familiars (type 3) are fine, Effects (type 1000) are fine, Slots (type 6) are fine.

Auto-incrementation works completely different for NPCs so this does not apply there.

I haven't ever done it with any other special entity types (1, 2, 4, 7, 8, 9), since generally speaking there isn't a good reason to make variants of them over just using data tags. Tears especially aren't a great idea since some tear effects are linked to their variants rather than a tear flag (haemolachria).

[Xalum]

I'm also realising now that variant 0 for Players, Tears, Bombs, Knives, & Projectiles is already populated, so this doesn't apply to them at all.

It's only an issue for pickups since variant 0 has function without being populated.

[Zamiell]

If you want to auto-increment pickup variants you have to first add a filler entry that absorbs variant 0, so that the rest of your entries can auto-increment safely.

I discovered today that doing this is not safe. In other words, having an entity of

<entity name="Placeholder Pickup" id="5" />

or

<entity name="Placeholder Pickup" id="5" variant="0" />

in your content/entities2.xml file both accomplish the same thing of making "Placeholder Pickup" be equal to 5.0.
However, this can crash the game under certain conditions.

Steps to reproduce:

g guppy's eye
l Game():Spawn(EntityType.ENTITY_PICKUP, PickupVariant.PICKUP_CHEST, Vector(200, 200), Vector.Zero, nil, 0, 106995962)

If you remove the placeholder pickup from your content/entities2.xml file, then the game will no longer crash.

[Xalum]

This crashes because your 5.0 entity doesn't have an anm2path for guppy's eye to render

[Zamiell]

According to Xalum, effects (in addition to pickups) are not safe for auto-incrementation, which doesn't seem to be documented anywhere. He says that this is presumably because of EffectVariant.STARFLASH (40).