Is there any way to control whether to render blocks or not (standard blocks and model based blocks) based on the player state (e.g. having equipped an item or holding an item) without using a TESR?

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Do you know of any open source 1.12 mod using the mentioned "Item override mechanic" or the other "TextureAtlasSprite" techniques?

13 minutes ago, Bregor said:

Do you know of any open source 1.12 mod using the mentioned "Item override mechanic" or the other "TextureAtlasSprite" techniques?

 

Minecraft itself has several models that use overrides, e.g. the compass, bow, elytra and clock; though overrides only apply to item models, not to block models.

 

I don't know of any mods that use the TextureAtlasSprite technique.