Hat tutorial

docs/tutorials/hat.md

@@ -0,0 +1,71 @@
+## /hat with ModAPI
+/hat is a common server-side plugin that lets you put any block/item on your head. This tutorial will explain how to register a server-side command, construct a packet, and send it to a player.
+[`S09PacketHeldItemChange` constructors]()
+
+
+As always, start with the basic boilerplate IIFE with credits:
+```javascript
+(function HatMod() {
+    ModAPI.meta.title("Hat Mod");
+    ModAPI.meta.description("Use /hat to put anything on your head.");
+    ModAPI.meta.credits("By <author_name>");
+})();
+```
+In order to add a server side command, we need to:
+- Write a function to run on the server.
+- In this function, we'll add a listener to the [`processcommand` event](../apidoc/events.md#server-side-events)
+- We'll check if the command is `/hat`
+- If it is, we'll swap their head and current hand inventory slots, and send a network packet.
+- Finally, the function from step 1 is thrown into [`ModAPI.dedicatedServer.appendCode`](../apidoc/dedicatedserver.md)
+
+Here's the completed code:
+```javascript
+(function HatMod() {
+    ModAPI.meta.title("Hat Mod");
+    ModAPI.meta.description("Use /hat to put anything on your head.");
+    ModAPI.meta.credits("By <author_name>");
+
+    ModAPI.dedicatedServer.appendCode(function serverSideCode() {
+        // Find the constructor for the held item change packet that has only one argument.
+        // This will be used to notify the client that their hotbar has been updated.
+        // Reference: https://nurmarvin.github.io/Minecraft-1.8-JavaDocs/net/minecraft/network/play/server/S09PacketHeldItemChange.html
+        var S09PacketHeldItemChange_Constructor = ModAPI.reflect.getClassByName("S09PacketHeldItemChange").constructors.find(x => x.length === 1);
+
+        //Add an event listener for when a command is processed on the server.
+        ModAPI.addEventListener("processcommand", (event) => {
+            // If the command starts with /hat
+            if (event.command.toLowerCase().startsWith("/hat")) {
+                // Exit if the sender isn't a player
+                if (
+                    !ModAPI.reflect.getClassById("net.minecraft.entity.player.EntityPlayerMP").instanceOf(
+                        event.sender.getRef()
+                    )
+                ) {
+                    return
+                };
+
+                // Get the current held item
+                var heldItem = event.sender.inventory.getCurrentItem();
+
+                // Get the contents of the helmet slot
+                var armorItem = event.sender.inventory.armorInventory[3];
+
+                // Get the inventory index of the current held item
+                var hotbarIdx = event.sender.inventory.currentItem;
+
+                // Set the helmet slot to heldItem.getRef() (raw java object) if heldItem exists, otherwise set it to null
+                event.sender.inventory.armorInventory[3] = heldItem ? heldItem.getRef() : null;
+
+                // Set the hotbar slot to the original value of the helmet slot if it has a value, otherwise set it to null
+                event.sender.inventory.mainInventory[hotbarIdx] = armorItem ? armorItem.getRef() : null;
+
+                // Make a packet to notify the client that the selected hotbar slot has been updated.
+                event.sender.playerNetServerHandler.sendPacket(makePacketItemChange(hotbarIdx));
+
+                // Prevent the 'unknown command' error
+                event.preventDefault = true;
+            }
+        }
+    });
+})();
+```

docs/tutorials/index.md

@@ -21,9 +21,9 @@ Prerequisites:
 
 Tutorials:
 - [Disable All Particles](disable_all_particles.md)
-- [/hat mod](comingsoon)
-- [/spawnxp command](comingsoon)
 - [Slippery Mod](slippery.md)
+- [/hat mod](hat.md)
+- [/spawnxp command](comingsoon)
 
 ### Advanced
 Prerequisites:

examplemods/hats.js

@@ -9,9 +9,6 @@ ModAPI.dedicatedServer.appendCode(function () {
     // This will be used to notify the client that their hotbar has been updated.
     var makePacketItemChange = ModAPI.reflect.getClassByName("S09PacketHeldItemChange").constructors.find(x => x.length === 1);
 
-    // Find the method for sending packets.
-    var sendPacket = ModAPI.reflect.getClassByName("NetHandlerPlayServer").methods.sendPacket.method;
-
     // When the server is processing a command
     ModAPI.addEventListener("processcommand", (event) => {
         // If the command starts with /hat
@@ -35,7 +32,7 @@ ModAPI.dedicatedServer.appendCode(function () {
             event.sender.inventory.mainInventory[hotbarIdx] = armorItem ? armorItem.getRef() : null;
 
             // Use the sendPacket method to send a item change packet to the client.
-            sendPacket(event.sender.playerNetServerHandler.getRef(), makePacketItemChange(hotbarIdx));
+            event.sender.playerNetServerHandler.sendPacket(makePacketItemChange(hotbarIdx));
 
             event.preventDefault = true;
         }