Every year, almost like clockwork, my friend group boots up a Minecraft server, plays it like we have no life for 2-3 weeks, and then moves on with our lives. It's an absolute blast, but for some of us, myself included, it poses a major problem.

You see, at my core, I am a Counter-Strike player. I've been in an abusive relationship with that series for nearly a decade at this point. If you've ever watched somebody play Counter-Strike before, even if you have no knowledge of the game, one thing quickly becomes abundantly clear: every single Counter-Strike player has undiagnosed ADHD, constantly twirling their weapon around on the screen. I am very much included in this group.

However, Minecraft does not have this functionality. This means that during our group's Minecraft phase, I am forced to play the game without constantly flipping my sword around like a digital fidget spinner. But alas, while I do not currently possess the ability to twirl a grass block on my finger, I do possess a Computer Science degree, which means that we can fix this.

Like many people my age, Minecraft is actually what first got me in to coding and Computer Science. It was a mod for Minecraft, called ComputerCraft, in which I wrote my first lines of code. Despite this introduction, I have never actually made a mod for Minecraft myself. But how hard could it be?

Although it was announced a decade and a half ago, Minecraft has still yet to receive an official mod API. This means that we must rely on the community to provide this functionality. When I was growing up, this was done nearly exclusively with the Forge mod loader, which is still around. Today, Forge is still around somewhat, but it seems like the community has largely shifted to a mod loader called Fabric, which claims to be both easier to use and more performant than Forge. I also happen to already have a couple of quality of life mods installed in my game, which are already running on Fabric, so I'll use this platform to develop my own mod.

Fabric, to their credit, has a quite thorough install and setup guide for new developers. I followed it, and within about 10 minutes, I had it installed. I went ahead and tried to compile and run the template mod...and it didn't work. Says that it couldn't find some of the referenced libraries. No worries, I thought, it's probably just Gradle being weird, so I went ahead and wiped it and rebuilt. Nope. It turns out that when you download the template mod from Fabric, by default it groups all of the Minecraft sources together in a way that breaks everything. You have to uncheck the box that says combine client and server. So, I start over, unchecking that box, and it finally works.

Remember when I said that Minecraft has no official modding API? That means that when it comes to overriding Minecraft's functions, you're working blind. Doing things like adding a new block or item have been fairly well documented by the community, but doing anything with the player's viewmodel, like adding an animation to it, is effectively undocumented. This was going to require some digging.

Fortunately, most mods in the Minecraft community are open source, which meant that I had reference material to work with. I went looking for mods that I figured would need to hook in to the same parts of Minecraft that I would, and within about an hour found out where I needed to be.

Minecraft is written in Java, which means that you can interface with the game's code with Mixins, which essentially allow you to inject code into a class. In my case, I located the HeldItemRenderer class, which takes care of displaying what item your player is currently holding on the screen. From here, I overrode renderItem class, adding a check to see if the player had recently pressed the inspect key (which I also added), and if so made a call to a custom class to handle playing the inspect animation.

Animations in Minecraft, to put it charitably, suck. Rather than allowing you to import from another 3D program like Unity does, Minecraft requires you to hard code your animations in a JSON file. Yuck. There is another way, but it's really no better. Instead of the JSON file, you can hard code your animation in Java by gradually offsetting the matrices that tell the game where to render the item. I actually opted to do it this way, as hand defining a bunch of keyframes in a JSON file didn't sound appealing. As such, I created a system for tracking the animations state, and depending on that state we lerp between predefined poses. The entire animation is then handled by a single switch statement. It's ugly, but it works. You can see it below.

With that sorted, all that was left was to polish the animation, add control logic for the keypress and animation state, and done. The mod works, and works well at that. As it stands, it uses the same animation for every item. In the future, I can expand this to give each item or item type a unique animation, but that's a project for a rainy day sometime. 

I actually learned quite a bit with this project. This was my first time working with a codebase as large as Minecraft's, so I believe having that exposure will help a great deal in my future projects.

The full source for this project is on my GitHub. I also created a Modrinth page, on the off chance I remember to update this project to the latest Minecraft versions.