This tutorial will cover making custom items with ModAPI. It is recommended that you follow the custom block tutorial first, as this tutorial is more fast-paced. The custom item we’ll be adding will set the player’s velocity to a random value when used, to demonstrate how methods can be overridden.
We’ll begin with a constant item texture encoded into a data URI, as well as some metadata.
(function CustomItemMod() {
const itemTexture = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAAAXNSR0IArs4c6QAAAKZJREFUOE9j/P//PxMDBIBoEP6HREOl4PLIciA2AyPIgMcM//7KgvWSDJjBBpx9/+YvJzc3Sbq12DhB6sEGsJ19/+YnmQawYhigzc7FcPXnN4KugbqAHWQAy9n3b34T4wJkw6EGYLqAoNVQBWS5ANlwZBfAvUCs/0EGkW0AzBKqGoCSDgh5A80F2KMRpAgfAKUT6kcjsfEPUycmKMQgy8AETkgUZWcAS3CPIf4oSPsAAAAASUVORK5CYII=";
ModAPI.meta.title("Custom Item Mod");
ModAPI.meta.icon(itemTexture);
ModAPI.meta.description("it's a custom item. what more do you want");
ModAPI.meta.credits("By <author_name>");
})();
Add a function that will contain the code to register the item called CustomItem. Inside it we’ll do something really similar to the custom blocks tutorial, where we’ll define a custom item class, and then register it (or, if on the server, wait until the bootstrap event fires). The reason it’s contained in a function is to make the job of running the same code on the server and client easier.
(function CustomItemMod() {
//...
function CustomItem() {
var creativeMiscTab = ModAPI.reflect.getClassById("net.minecraft.creativetab.CreativeTabs").staticVariables.tabMisc; //chuck it in the miscellaneous category ig
var itemClass = ModAPI.reflect.getClassById("net.minecraft.item.Item"); //Get the item class
var itemSuper = ModAPI.reflect.getSuper(itemClass, (x) => x.length === 1); //Get the super() function of the item class that has a length of 1
function CustomItem() {
itemSuper(this); //Use super function to get block properties on this class.
this.$setCreativeTab(creativeMiscTab); //Set the creative tab of the item to be the misc tab
}
ModAPI.reflect.prototypeStack(itemClass, CustomItem); // ModAPI equivalent of `extends` in java
CustomItem.prototype.$onItemRightClick = function ($itemstack, $world, $player) { //example of how to override a method
//use ModAPI.util.wrap to create a proxy of the player and the world without $ prefixes on the properties and methods
var player = ModAPI.util.wrap($player);
var world = ModAPI.util.wrap($world);
if (!world.isRemote) { //If we are on the server
// Math.random() returns a number from 0.0 to 1.0, so we subtract 0.5 and then multiply by 2 to make it become -1.0 to 1.0 instead
player.motionX += (Math.random() - 0.5) * 3;
player.motionZ += (Math.random() - 0.5) * 3;
player.motionY += Math.random() * 1.5; // gravity is a thing, so no negative numbers here otherwise it'll be boring
}
return $itemstack;
}
// Internal registration function. This will be used to actually register the item on both the client and the server.
function internal_reg() {
// Construct an instance of the CustomItem, and set it's unlocalized name (translation id)
var custom_item = (new CustomItem()).$setUnlocalizedName(
ModAPI.util.str("custom_item")
);
//Register it using ModAPI.keygen() to get the item id.
itemClass.staticMethods.registerItem.method(ModAPI.keygen.item("custom_item"), ModAPI.util.str("custom_item"), custom_item);
//Expose it to ModAPI
ModAPI.items["custom_item"] = custom_item;
//return the instance.
return custom_item;
}
//if the item global exists (and it will on the client), register the item and return the registered instance.
if (ModAPI.items) {
return internal_reg();
} else {
//Otherwise attatch the registration method to the bootstrap method.
ModAPI.addEventListener("bootstrap", internal_reg);
}
}
})();
Now let’s run the CustomItem function on the server and the client, and then use AsyncSink to create an in-memory resource pack to load item textures and models!
(function CustomItemMod() {
const itemTexture = "...";
ModAPI.meta.title("Custom Item Mod");
ModAPI.meta.icon(itemTexture);
ModAPI.meta.description("it's a custom item. what more do you want");
ModAPI.meta.credits("By <author_name>");
function CustomItem() {
// ...
}
// Run the function when the dedicated server loads.
ModAPI.dedicatedServer.appendCode(CustomItem);
// Run the function on the client
var custom_item = CustomItem();
ModAPI.addEventListener("lib:asyncsink", async () => {
ModAPI.addEventListener("lib:asyncsink:registeritems", (renderItem)=>{
renderItem.registerItem(custom_item, ModAPI.util.str("custom_item"));
});
AsyncSink.L10N.set("item.custom_item.name", "Cool Custom Item");
AsyncSink.setFile("resourcepacks/AsyncSinkLib/assets/minecraft/models/item/custom_item.json", JSON.stringify(
{
"parent": "builtin/generated",
"textures": {
"layer0": "items/custom_item"
},
"display": {
"thirdperson": {
"rotation": [ -90, 0, 0 ],
"translation": [ 0, 1, -3 ],
"scale": [ 0.55, 0.55, 0.55 ]
},
"firstperson": {
"rotation": [ 0, -135, 25 ],
"translation": [ 0, 4, 2 ],
"scale": [ 1.7, 1.7, 1.7 ]
}
}
}
));
AsyncSink.setFile("resourcepacks/AsyncSinkLib/assets/minecraft/textures/items/custom_item.png", await (await fetch(
itemTexture
)).arrayBuffer());
});
})();
That’s it! Upload your completed mod, run .reload_tex in chat in a singleplayer world and use your new item!
completed mod