[1.18.2] Generate loot from loot table

[Sweetmimike]

Hello,

I just wanted to know if it exists a way of generating programmatically a loot when you have the loot table.

In my case I've got the loot table from a resouce location but I don't understand how I need to use the LootContext ect ...

Here is my code : 

ResourceLocation loc = new ResourceLocation(resourcePath);

LootTables ltManager = this.getLevel().getServer().getLootTables();
LootTable lt = ltManager.get(loc);
LootContextParamSet ltps = lt.getParamSet();
               
LootContext.Builder builder = new LootContext.Builder((ServerLevel) this.level);
List<ItemStack> generated =  lt.getRandomItems(builder.create(ltps));

 

[Draco18s]

TLDR, in order to generate loot from a loot table you need to pass in all of the relevant context for that kind of loot table, because "I just need cow loot" requires knowing if the cow was on fire. And if the player was holding a sword with the looting enchantment.

Etc etc etc.

So you need to specify where the loot is being dropped, who cause it to drop, what is being dropped, and so on. All of that it put into the loot context builder.

Look for existing usages of LootContextParamSets

(Oh and be sure to pass the result through ForgeHooks.modifyLoot)

Edited May 30, 2022 by Draco18s

[Sweetmimike]

Hello,

Thank you for your anwsers, I finally succeeded. I have just one more question : 

Why in the code below, the parameter TOOL is not considered ? Indeed, when I try to generate loot from a cow, it generates beef whereas I added a parameter TOOL with a diamond sword with fire aspect, so It should generate Steak.

ResourceLocation loc = new ResourceLocation(resourcePath);

LootTables ltManager = this.getLevel().getServer().getLootTables();
LootTable lt = ltManager.get(loc);

ItemStack sword = new ItemStack(Items.DIAMOND_SWORD);
sword.enchant(Enchantments.MOB_LOOTING, 3);
sword.enchant(Enchantments.FIRE_ASPECT, 1);


Vec3 position = new Vec3(getBlockPos().getX(), getBlockPos().getY(), getBlockPos().getZ());
LootContext.Builder builder = (new LootContext.Builder((ServerLevel) this.level))
                        .withParameter(LootContextParams.TOOL, sword)
                        .withParameter(LootContextParams.ORIGIN, position);

LootContext ctx = builder.create(LootContextParamSets.FISHING);
List<ItemStack> generated = lt.getRandomItems(ctx);

 

[Choonster]

19 minutes ago, Sweetmimike said:

Hello,

Thank you for your anwsers, I finally succeeded. I have just one more question : 

Why in the code below, the parameter TOOL is not considered ? Indeed, when I try to generate loot from a cow, it generates beef whereas I added a parameter TOOL with a diamond sword with fire aspect, so It should generate Steak.

If you look at the loot table for cows, you'll see that it checks whether the entity is on fire to determine whether to drop steak; not whether the tool has Fire Aspect.

[Sweetmimike]

11 minutes ago, Choonster said:

If you look at the loot table for cows, you'll see that it checks whether the entity is on fire to determine whether to drop steak; not whether the tool has Fire Aspect.

Yes indeed

And for the looting enchant ? It seems to not be considered

[Draco18s]

11 hours ago, diesieben07 said:

No, LootTable#getRandomItems already does that.

👍

Haven't traced all the calls lately, as I haven't been doing any active modding.

33 minutes ago, Sweetmimike said:

And for the looting enchant ? It seems to not be considered

I believe that is a separate context entry.

[Sweetmimike]

1 hour ago, Draco18s said:

I believe that is a separate context entry.

What do you mean about that ? Do you think it is possible to apply a looting effect to the LootContext ?

[Draco18s]

Yes, but like I said, it's been a while since I looked at the relevant code.