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Dynamic Loot Modification (view source)
Revision as of 18:30, 20 September 2022
, 18:30, 20 September 2022Fix the explanation
#* This will contain all of the data about your modification and allows data packs to tweak your effect.
#* This will contain all of the data about your modification and allows data packs to tweak your effect.
# A class that extends <code>LootModifier</code>
# A class that extends <code>LootModifier</code>
#* The operational code that makes your modifier work and associated serializer.
#* The operational code that makes your modifier work and associated codec.
Finally, the serializer for your operational class is [[Registration|registered]] as any other <code>ForgeRegistryEntry</code>.
Finally, the codec for your operational class is [[Registration|registered]] as any other registry object.
==The global_loot_modifiers.json==
==The global_loot_modifiers.json==
},
},
{
{
"condition": "block_state_property",
"condition": "minecraft:block_state_property",
"block":"minecraft:wheat"
"block": "minecraft:wheat"
}
}
],
],
In the above example, the modification only happens if the player harvests wheat when using shears (specified by the two <code>conditions</code> which are automatically <code>AND</code>ed together). The <code>seedsItem</code> and <code>numSeeds</code> values are then used to count how many seeds were generated by the vanilla loot table, and if matched, are substituted for an additional <code>replacement</code> item instead. The operation code will be shown below.
In the above example, the modification only happens if the player harvests wheat when using shears (specified by the two <code>conditions</code> which are automatically <code>AND</code>ed together). The <code>seedsItem</code> and <code>numSeeds</code> values are then used to count how many seeds were generated by the vanilla loot table, and if matched, are substituted for an additional <code>replacement</code> item instead. The operation code will be shown below.
{{Tip|<code>conditions</code> is the only object needed by the system specification, everything else is the mod maker's data.
<code>seedItem</code>, <code>numSeeds</code> and <code>replacement</code> are NOT standard elements of Global Loot Modifiers.
They are deserialized manually in the next section.}}
== The LootModifier Subclass ==
== The LootModifier Subclass ==
You will also need a static child class that extends <code>GlobalLootModifierSerializer<T></code> where <code>T</code> is your LootModifier subclass in order to deserialize your json data file into operational code.
You will also need a <code>Codec<T></code> where <code>T</code> is your LootModifier subclass in order to deserialize your json data file into operational code. The codec must be [[Registration|registered]].
<syntaxhighlight lang="java">
<syntaxhighlight lang="java">
private static class WheatSeedsConverterModifier extends LootModifier {
/**
* When harvesting wheat with shears, this modifier is invoked via the wheat_harvest loot_modifier json<br/>
* This modifier checks how many seeds were harvested and turns X seeds into Y wheat (3:1)
*
*/
// Assume there exists a <code>IForgeRegistry<Codec<T extends LootModifier>></code> LOOT_MODIFIER_REGISTRAR added by a mod
private static class WheatSeedsConverterModifier extends LootModifier
{
public static final RegistryObject<Codec<WheatSeedsConverterModifier>> CODEC = LOOT_MODIFIER_REGISTRAR.register("wheat_seeds_converter", () ->
RecordCodecBuilder.create(inst -> codecStart(inst).and(
inst.group(
Codec.INT.fieldOf("numSeeds").forGetter(m -> m.numSeedsToConvert),
ForgeRegistries.ITEMS.getCodec().fieldOf("seedItem").forGetter(m -> m.itemToCheck),
ForgeRegistries.ITEMS.getCodec().fieldOf("replacement").forGetter(m -> m.itemReward)
)).apply(inst, WheatSeedsConverterModifier::new)
));
private final int numSeedsToConvert;
private final Item itemToCheck;
private final Item itemReward;
public WheatSeedsConverterModifier(LootItemCondition[] conditionsIn, int numSeeds, Item itemCheck,
Item reward)
{
super(conditionsIn);
numSeedsToConvert = numSeeds;
itemToCheck = itemCheck;
itemReward = reward;
}
@NotNull
@Override
public ObjectArrayList<ItemStack> doApply(ObjectArrayList<ItemStack> generatedLoot, LootContext context) {
//
// Additional conditions can be checked, though as much as possible should be parameterized via JSON data.
// It is better to write a new ILootCondition implementation than to do things here.
//
int numSeeds = 0;
generatedLoot.stream().filter(stack -> stack.getItem() == itemToCheck)
.forEach(stack -> numSeeds+=stack.getCount())
if(numSeeds >= numSeedsToConvert) {
generatedLoot.removeIf(x -> x.getItem() == itemToCheck);
generatedLoot.add(new ItemStack(itemReward, (numSeeds/numSeedsToConvert)));
numSeeds = numSeeds%numSeedsToConvert;
if(numSeeds > 0)
generatedLoot.add(new ItemStack(itemToCheck, numSeeds));
}
return generatedLoot;
}
@Override
public Codec<? extends IGlobalLootModifier> codec() {
return CODEC.get();
}
}
}
</syntaxhighlight>
</syntaxhighlight>
The critical portion is the <code>doApply</code> method.
The critical portion is the <code>doApply</code> method.
This method is only called if the <code>conditions</code> specified return <code>true</code> and the modder is now able to make the modifications they desire. In this case we can see that the number of <code>itemToCheck</code> meets or exceeds the <code>numSeedsToConvert</code> before modifying the list by adding an <code>itemReward</code> and removing any excess <code>itemToCheck</code> stacks, matching the previously mentioned effects: When a wheat block is harvested with shears, if enough seeds are generated as loot, they are converted to additional wheat instead.
This method is only called if the <code>conditions</code> specified return <code>true</code> and the modder is now able to make the modifications they desire. In this case we can see that the number of <code>itemToCheck</code> meets or exceeds the <code>numSeedsToConvert</code> before modifying the list by adding an <code>itemReward</code> and removing any excess <code>itemToCheck</code> stacks, matching the previously mentioned effects: ''When a wheat block is harvested with shears, if enough seeds are generated as loot, they are converted to additional wheat instead''.
The codec can also be used for [[datageneration|data generation]] with a <code>GlobalLootModifierProvider</code>.
Additional [https://github.com/MinecraftForge/MinecraftForge/blob/1.15.x/src/test/java/net/minecraftforge/debug/gameplay/loot/GlobalLootModifiersTest.java examples] can be found on the Forge Git repository, including silk touch and smelting effects.
Additional [https://github.com/MinecraftForge/MinecraftForge/blob/1.19.x/src/test/java/net/minecraftforge/debug/gameplay/loot/GlobalLootModifiersTest.java examples] can be found on the Forge Git repository, including silk touch and smelting effects.