Allow setting item texture from stack metadata

[lisacvuk]

Solves #5686

To do

This PR is a Work in Progress

• Fix things like rails not properly changing texture in both wield model and inventory
• Use ItemStack::getTexture in more places instead of manually checking if metadata exists

How to test

minetest.register_chatcommand("test",` {  
   params = "",  
   func = function(name, param)  
              local player = minetest.get_player_by_name(name)  
              local stack = player:get_wielded_item()  
              stack:get_meta():set_string("texture", "default_leaves.png")  
              player:set_wielded_item(stack)  
          end,  
})  

[sorcerykid]

Correct me if I'm wrong, but doesn't this have the potential to break mods that already use the "texture" field of itemstack metadata? As more and more specialized fields like this are added, I'm concerned that this will cause conflicts down the road.

Perhaps it should have been decided that specialized fields be denoted using a underscore prefix or some other convention so that there's never any risk of naming collisions when the API is changed.

[ghost]

Perhaps it should have been decided that specialized fields be denoted using a underscore prefix or some other convention so that there's never any risk of naming collisions when the API is changed.

While I don't expect that many (any?) mods use this particular field, I definitely support adopting a standard naming convention for metadata fields used by the engine.

[lisacvuk]

I can make this use "_texture", it shouldn't be difficult to change description to "_description" as well.

[sorcerykid]

That is great news, and thanks for the clarification!

I am very much looking forward to this PR. I can't even imagine all the potential applications. Once this is merged, hopefully it sets a precedent for the long awaited ability to dynamically change textures of nodes using the same methodology. One step at a time, but at least this is a great step in that direction :)

[Skamiz]

I believe it is worth noting that the documentation on item definitions encurages modders to use an underscore for custom item/node definition fields.
https://github.com/minetest/minetest/blob/master/doc/lua_api.txt#L6578

        _custom_field = whatever,
        -- Add your own custom fields. By convention, all custom field names
        -- should start with `_` to avoid naming collisions with future engine
        -- usage.
`

[sorcerykid]

Thanks for the heads up. To be clear, those are item definition fields, which are separate and distinct from metadata fields that are serialized within the itemstack or node.

[paramat]

PR is WIP but no progress for 4 months, is @lisacvuk still interested in continuing work?
Feature has core dev support in the feature request.

[sorcerykid]

I would like to respectfully retract my earlier suggestion of using underscores for reserved fields in consideration of the fact that infotext and formspec are widely used already for node meta. Since no standard was picked early on, it's probably best not to introduce an more confusion by switching the naming scheme now.

My secondary impetus, however, is that I've been considering opening a PR to streamline private node meta by prefixing an underscore to the name, rather than having to use the somewhat obfuscated method mark_as_private and storing an extra boolean value in the database. So I feel that would be a better application of the underscore.

[lisacvuk]

I will close this for now, as I don't have time (or interest) to work on it right now. Feel free to take over if you wish.

[velartrill]

if there's still interest in this (read "it's likely to eventually be merged") i'd be willing to take it over

[rubenwardy]

There's definitely interest in this feature, haven't checked this specific implementation though