If you've been banging your head against the wall trying to get your roblox custom humanoid filter script to stop flagging the wrong things or ignoring your custom rig entirely, you are definitely not alone. It's one of those things in Roblox development that sounds simple on paper but turns into a total nightmare once you actually start grouping parts together and expecting the physics engine to play nice. We've all been there—you spend hours modeling a cool quadraped or some Eldritch horror, only to find out the default humanoid behavior doesn't know what to do with it.
The reality is that the standard Roblox Humanoid is a bit of a legacy mess. It was built for blocky R6 characters back in the day, and while R15 made things a bit better, it still struggles when you try to do something outside the box. That's where a custom filter script comes in. You need a way to tell the engine, "Hey, ignore these specific parts when you're checking for collisions or raycasting," and that's surprisingly tricky to get right without making your game lag like crazy.
Why the default behavior usually fails
When you drop a standard Humanoid into a model that isn't a standard character, Roblox tries its best to treat it like a person. It looks for a "Head," a "Torso," and it tries to apply these built-in internal filters for things like the camera and basic movement. But as soon as you add armor, wings, or extra limbs, the default system starts tripping over itself.
If you don't have a solid roblox custom humanoid filter script, you'll notice things like the camera zooming into your character's brain every time you walk near a wall, or worse, your character's own limbs triggering "touched" events that should be reserved for enemies. It's incredibly frustrating to build a complex boss and then realize its own tail is what's killing it because the damage script can't tell the difference between the boss and the player.
Setting up your RaycastParams
The secret sauce to a good filter script nowadays is RaycastParams. If you're still using the old TargetFilter property on the Mouse or legacy raycasting methods, you're making life harder than it needs to be. RaycastParams allows you to create a specific list of objects that the engine should just pretend don't exist.
When you're writing your script, you want to create a new RaycastParams object and set its FilterDescendantsInstances property to a table containing your humanoid model. By setting the FilterType to Enum.RaycastFilterType.Exclude, you basically tell the script to look through everything except your character. This is huge for things like custom weapon systems or interaction prompts. You don't want your sword swing to hit your own arm just because your arm was in the way of the raycast for one frame.
The struggle with CollectionService
Honestly, one of the cleanest ways to manage a roblox custom humanoid filter script is by using CollectionService. Instead of manually adding every single part of your humanoid to a table, you can just tag the model or specific "ignore-able" parts with a string like "CharacterPart" or "FilterMe."
Then, in your script, you can just pull everything with that tag and shove it into your filter list. It's way more dynamic. If you're spawning enemies or players constantly, you don't want to be manually updating your filter tables every two seconds. Using tags means the script just handles it automatically as things enter and leave the workspace. It's a lifesaver for performance, especially in games with high player counts where everyone is running around with different custom rigs.
Dealing with the Camera
We have to talk about the camera because it's usually the first thing that breaks. If your custom humanoid has massive wings or a long tail, the default Roblox camera is going to hit those parts and zoom in until you're staring at a pixelated texture. It's annoying for the player and looks unprofessional.
Your filter script needs to hook into the camera logic. You can actually set the Camera.CameraSubject to a specific part, but that doesn't always solve the clipping. A lot of devs end up writing a small loop or using RunService.RenderStepped to constantly ensure the camera's raycasting ignore list includes the entire character hierarchy. It sounds like overkill, but it's the only way to get that smooth, triple-A feel where the camera ignores the player's geometry but still collides with the environment correctly.
Performance: Don't kill the frame rate
One trap I see a lot of people fall into is creating a new RaycastParams object every single time a ray is cast. Please, don't do that. It's a memory hog and will eventually cause micro-stutters. You should define your params once, maybe update the filter table when a character spawns or changes, and then just reuse that object.
Roblox handles tables pretty well, but if your roblox custom humanoid filter script is trying to rebuild a list of 500 parts sixty times a second, the server (or the client's CPU) is going to start sweating. Keep your filter lists lean. You don't always need to include every tiny detail; sometimes just including the main folders or the top-level model is enough to get the job done.
Handling "Ghost" Parts
Sometimes, even with a script, you'll find parts that just refuse to be filtered. This usually happens when you have nested models or things that are being dynamically parented during gameplay. I've found that the best way to handle this is to have the script listen for DescendantAdded on the humanoid model.
If a new piece of armor gets equipped, the script should automatically detect it and toss it into the FilterDescendantsInstances table. If you don't do this, your custom humanoid might work fine until the player picks up an item, and suddenly the whole physics system goes wonky again because the new item wasn't on the "ignore" list.
Why this matters for combat
If you're making a fighting game or anything with projectiles, your roblox custom humanoid filter script is basically the most important piece of code you'll write. There is nothing worse than firing a fireball only for it to explode in your own face because the hit detection script touched your own hitbox.
By using a centralized filter, you can ensure that every projectile, every melee hit, and every "is a wall in the way?" check uses the exact same logic. It makes your game feel consistent. When players feel like the game's physics are working against them, they quit. When the physics are invisible because they work so well, they keep playing.
Final thoughts on debugging
If things aren't working, use the Print debugger. I know it sounds basic, but printing out the contents of your filter table will save you so much time. Sometimes you'll realize the script isn't even seeing the parts you thought it was. Also, check your CanTouch and CanQuery properties. Sometimes the issue isn't the script; it's the fact that you have a part set to ignore all queries, which messes with how the filter interacts with it.
Anyway, building a roblox custom humanoid filter script isn't exactly a walk in the park, but once you get the hang of RaycastParams and CollectionService, it becomes second nature. Just keep it clean, watch your performance, and make sure you're account for all those weird edge cases like equipped tools and wing attachments. Once it's locked in, your custom characters will finally start behaving like they belong in the game instead of fighting against it.