I would like to move the HumanoidRootPart in an animation. This has lead me to try and implement a root motion-based system.
I’ve started by converting a KeyframeSequence into a table. I plan to base the HumanoidRootPart data off the Torso/LowerTorso CFrame values in the table.
Problems I’ve encountered are:
AlignPosition, BodyPosition and other body movers/constraints are too ‘laggy’
Setting the CFrame directly doesn’t account for collision
Humanoid:Move is limited to the walkspeed of the humanoid
Scouring the internet, I can’t see anyone that’s implemented a system like this. Anyone have any ideas?
That’s easy enough to do; just manipulate the Motor6D.Transform property based on the animation data.
I think I’ll just try to set the CFrame directly anyways despite the collision issue. I’ll just have to trust that the CFrame movements are small enough in my animation to have collision resolution work properly.
Unfortunately there isn’t an engine feature for root motion. I’ve also tried searching Google, the DevForum, and the DevHub but have found nothing relating to a root motion feature on Roblox’s engine. Most I’ve found are some hacky solutions such as using body movers like you said or changing the position of the character to a position of one of the body parts at the end of the animation (source: How do you move the humanoidrootpart with an animation?) but I don’t recommend using them. There is a feature request for root motion already posted as well.
I see what you’re trying to go for by “animating the HumanoidRootPart directly”, but I’m not sure if you can actually do this. I haven’t tried myself though. Setting the HumanoidRootPart’s CFrame directly based on animation data wouldn’t work either as animations are relative to the HumanoidRootPart, so it would just keep sending you forward (I think; once again I haven’t actually tried this so feel free to correct me if I’m wrong).
You’d think this would’ve already been implemented as it’s a pretty essential feature. For my case, I’ve been working and planning on a baseball project and one of the main issues I’m encountering is how I’m going to go about animations (especially fielding animations). The best I can come up with is moving the character manually along a pre-defined path as the animation is playing and also adjust movement speed accordingly while the animation is playing. Obviously, this will require lots of trial and error. The animation itself would have to be in-place.
I still haven’t made a decision on what I’m going to do for the animations in my project but I might just end up dealing with with the fact that there’s no root motion feature and make the best out of it, unless I feel like torturing myself with the method I proposed.
It should be possible: just store the initial HumanoidRootPart CFrame as the reference point for your animation. I didn’t do that method anyways. If I did, I might as well have created the framework for a custom animation engine.
I used another rig to base the root motion on.
How this works is that:
RootMotionRig PrimaryPart CFrame is set at the HumanoidRootParts initial CFrame
HumanoidRootPart’s CFrame is set to RootMotionPoint’s Motor6D.Transform CFrame every frame
It works fine if you don’t care about collision. I implemented raycast collision, but it’s very primitive.
Decided to try out your method with the rig and I got very satisfactory results as you can see in this video.
What I did was I added two animations (or more like copied with slight variation) with a script which are both derived from the original animation, which is the running direction change as shown in the video.
One of the animations is for the root motion rig. The motion point’s transform CFrame is based on the LowerTorso’s CFrame, except orientation is only from side to side and movement is only on the X and Z axes. The Y value stays the same.
The second animation is basically the original animation but in-place. Lower torso only moves on the Y axis.
Play both animations at the same time and you get root motion.
Here’s what I’ve got after working on this problem for a little bit.
local RunService = game:GetService("RunService")
local Humanoid = script.Parent.Humanoid
local Animator = Humanoid.Animator
Humanoid.AutoRotate = false
local Animation = Instance.new("Animation")
Animation.AnimationId = "rbxassetid://10320606948" -- AerialEvade
-- You have to use your own animation which includes root transform.
local Track = Animator:LoadAnimation(Animation)
Track:Play(0, 1, 1)
local RootJoint = script.Parent.LowerTorso.Root
local RootPart = Humanoid.RootPart
local LastTransform = RootJoint.Transform
local LastOrientation = CFrame.identity
local XZPlane = Vector3.new(1, 0, 1)
local function MoveHumanoid(Humanoid, Direction, dt)
local Distance = Direction.Magnitude
Humanoid.WalkSpeed = Distance / dt
if Distance > 0 then
Humanoid:Move(Direction.Unit, false)
else
Humanoid:Move(Vector3.zero, false)
end
end
local function OrientationFromTransform(Transform)
local _, Heading, _ = Transform:ToEulerAngles(Enum.RotationOrder.YXZ)
local Orientation = CFrame.fromEulerAngles(0, Heading, 0, Enum.RotationOrder.YXZ)
return Orientation
end
Track.DidLoop:Connect(function()
LastTransform = RootJoint.Transform
LastOrientation = OrientationFromTransform(RootJoint.Transform)
end)
RunService.Stepped:Connect(function(_, dt)
local Transform = RootJoint.Transform
local Orientation = OrientationFromTransform(Transform)
local RelOrientation = LastOrientation:ToObjectSpace(Orientation)
RootPart.CFrame *= RelOrientation
local DeltaPos = Transform.Position - LastTransform.Position
-- Make motion relative to character root part.
local MoveMotion = (RootPart.CFrame * Orientation:Inverse()):VectorToWorldSpace(DeltaPos)
MoveHumanoid(Humanoid, MoveMotion, dt)
LastTransform = Transform
LastOrientation = Orientation
-- Remove XZ translation.
RootJoint.Transform -= RootJoint.Transform.Position * XZPlane
-- Rotates entire animation from origin.
-- It's fine that we rotate from origin since we just removed the XZ translation.
RootJoint.Transform = Orientation:Inverse() * RootJoint.Transform
end)
This basically extracts the XZ translation (position) and Y axis orientation of the animation from the transform of the root joint. These two components are removed from the transform so the animation looks like the one playing on the character named “RootTransformRemoved”.
The extracted position and orientation are then applied back in a way that moves the root part.
The position changed by setting Humanoid.WalkSpeed and calling Humanoid:Move() to move the needed amount and the orientation is changed by setting the CFrame of the root part.
This is not a final implementation but it’s just a test which shows this is possible.
For a final implemetation you would need to upload the animations as they appear on the “RootTransformRemoved” character and have a system which applies movement and rotation from the root motion extracted from the original animations.
Someone will have to create some tools to process an animation and extract the root motion.
Here’s the simplified code which should be more easy to understand.
local RunService = game:GetService("RunService")
local Humanoid = script.Parent.Humanoid
local Animator = Humanoid.Animator
-- Stop character from rotating towards direction of movement.
Humanoid.AutoRotate = false
local Animation = Instance.new("Animation")
Animation.AnimationId = "rbxassetid://10320606948" -- AerialEvade, probably private, can't use.
local Track = Animator:LoadAnimation(Animation)
Track:Play(0, 1, 1/4)
local RootJoint = script.Parent.LowerTorso.Root
local RootPart = Humanoid.RootPart
local LastTransform = RootJoint.Transform
local XZPlane = Vector3.new(1, 0, 1)
-- Move humanoid by a certain distance.
local function MoveHumanoid(Humanoid, Direction, dt)
local Distance = Direction.Magnitude
Humanoid.WalkSpeed = Distance / dt
if Distance > 0 then
Humanoid:Move(Direction.Unit, false)
else
Humanoid:Move(Vector3.zero, false)
end
end
-- This will basically remove the Y axis rotation of the transform.
-- Hard to explain.
local function GetTransform(Transform)
local _, Heading, _ = Transform:ToEulerAngles(Enum.RotationOrder.YXZ)
local Orientation = CFrame.fromEulerAngles(0, Heading, 0, Enum.RotationOrder.YXZ)
return Orientation + Transform.Position
end
Track.DidLoop:Connect(function()
LastTransform = RootJoint.Transform
end)
RunService.Stepped:Connect(function(_, dt)
local Transform = RootJoint.Transform
-- Get the delta (difference) between the transform this frame and last frame.
-- Delta is relative to LastTransform.
local RelativeDelta = GetTransform(LastTransform):ToObjectSpace(GetTransform(Transform))
LastTransform = Transform
-- Move the character by the delta (But make it move relative to current root part orientation).
local MoveMotion = RootPart.CFrame:VectorToWorldSpace(RelativeDelta.Position)
MoveHumanoid(Humanoid, MoveMotion, dt)
-- Rotate the character by the delta.
RootPart.CFrame *= RelativeDelta.Rotation
-- Code below removes root transform from the animation.
-- In a final implementation you need to preprocess the animation so you don't use the two lines below.
-- Remove joint translation. (Keep Y axis translation.)
RootJoint.Transform -= RootJoint.Transform.Position * XZPlane
-- Remove Y axis rotation from animation.
RootJoint.Transform = GetTransform(Transform).Rotation:Inverse() * RootJoint.Transform
end)
For R6 I believe the only change necessary would be to change the path of the RootJoint Motor6D instance.
local RootJoint = script.Parent.LowerTorso.Root -- From this.
local RootJoint = script.Parent.HumanoidRootPart["Root Hip"] -- To this.
You also have to upload your own R6 animation.
Animation.AnimationId = "rbxassetid://10320606948" -- Put your R6 animation here instead.
And remember that this is just a proof of concept. It won’t look correct from the clientside as the translation and rotation of the animation is only being removed from the server script.
R6 rigs don’t seem to have a Motor6D named Root, would it be best to make a custom rig for that? The root Motor6D on an R6 rig is under the HumanoidRootPart.
Finally got around to playing around with this, and it works wonderfully with R15 rigs. Unfortunately R6 animations don’t play well because of the rotations placed on the Root Motor6D.C0 and C1.
In this video, SwordRig is a normal R6 rig, while SwordRig2’s Root Hip was edited to have its C0 and C1 set to zero. SwordRig2 works as it should. If you or anyone else has a solution, please let me know.
Just needed to edit some values related to which axis the RootPart was rotating and translating on
-- Example of how you can extract root motion from an animation and apply it to the character.
-- Code by @Razorter
local RunService = game:GetService("RunService")
local Humanoid = script.Parent.Humanoid
local Animator = Humanoid.Animator
-- Stop character from rotating towards direction of movement.
Humanoid.AutoRotate = false
local Animation = Instance.new("Animation")
Animation.AnimationId = "rbxassetid://" -- insert r6 anim here
local Track = Animator:LoadAnimation(Animation)
Track:Play(0, 1, 1/2)
local RootPart = Humanoid.RootPart
local RootJoint = RootPart["Root Hip"]
local LastTransform = RootJoint.Transform
local XZPlane = Vector3.new(1, 1, 0)
-- Move humanoid by a certain distance.
local function MoveHumanoid(Humanoid, Direction, dt)
local Distance = Direction.Magnitude
Humanoid.WalkSpeed = Distance / dt
if Distance > 0 then
Humanoid:Move(Direction.Unit, false)
else
Humanoid:Move(Vector3.zero, false)
end
end
-- This will basically remove the Y axis rotation of the transform.
-- Hard to explain.
local function GetTransform(Transform)
local _, _, Heading = Transform:ToEulerAngles(Enum.RotationOrder.YXZ)
local Orientation = CFrame.fromEulerAngles(0, 0, Heading, Enum.RotationOrder.YXZ)
return Orientation + Transform.Position
end
Track.DidLoop:Connect(function()
LastTransform = RootJoint.Transform
end)
RunService.Stepped:Connect(function(_, dt)
local Transform = RootJoint.Transform
-- Get the delta (difference) between the transform this frame and last frame.
-- Delta is relative to LastTransform.
local RelativeDelta = GetTransform(LastTransform):ToObjectSpace(GetTransform(Transform))
LastTransform = Transform
-- Move the character by the delta (But make it move relative to current root part orientation).
local MoveMotion = RootPart.CFrame:VectorToWorldSpace(Vector3.new(RelativeDelta.Position.Z, 0, RelativeDelta.Position.Y))
MoveHumanoid(Humanoid, MoveMotion, dt)
-- Rotate the character by the delta.
local rx, ry, rz = RelativeDelta:ToOrientation()
RootPart.CFrame *= CFrame.Angles(rx, rz, ry)
-- Code below removes root transform from the animation.
-- In a final implementation you need to preprocess the animation so you don't use the two lines below.
-- Remove joint translation. (Keep Y axis translation.)
RootJoint.Transform -= RootJoint.Transform.Position * XZPlane
-- Remove Y axis rotation from animation.
RootJoint.Transform = GetTransform(Transform).Rotation:Inverse() * RootJoint.Transform
end)
the only problem with this is that the animation will have to be played server-side
with tools like a sword the animations are usually handled on client and the server handles damage
Why so? I don’t see the issue since the player has network ownership of their character anyway, but if you’re talking about security then that’s a whole other topic to delve into.
when an animation is played on the client, it will be smooth as it depends on your character and replicated to the server, however when its played on server it replicated to all clients and the smoothness of the animation could be alot worse depending on the characters connection
I feel like that’s just the unavoidable nature of server-client communication anyway if a player’s shoddy connection is causing animation lag. You do bring up a good point though, makes me wonder if this method has any potential desync between the root motion and animation.
