You can write your topic however you want, but you need to answer these questions:
1. What do you want to achieve? Keep it simple and clear!
- Simple, I want to make it not interfere with the animation
2. What is the issue? Include screenshots / videos if possible!
- Here’s the video showing the Inverse Kinematics interfere with the animation
3. What solutions have you tried so far? Did you look for solutions on the Developer Hub?
- Yes, I have but yet nothing helped me, I also tried using C1 as I heard animations don’t often use it, even Transform but it did not work at all.
I literally want it to not interfere with the animation, I’d have to make the arm transparent to not make it look weird.
R6IK:
credits to R6 Inverse Kinematics
local function SolveArmIK(originCFF, targetPos, l1, l2, C1Off, Side : "Left" | "Right")
-- build intial values for solving
local originCF
if Side == "Left" then
originCF = originCFF*CFrame.new(0,0,C1Off.X)
elseif Side == "Right" then
originCF = originCFF*CFrame.new(0,0,-C1Off.X)
end
local localized = originCF:pointToObjectSpace(targetPos)
local localizedUnit = localized.unit
local l3 = localized.magnitude
-- build a "rolled" planeCF for a more natural arm look
local axis = Vector3.new(0, 0, -1):Cross(localizedUnit)
local angle = math.acos(-localizedUnit.Z)
local planeCF = originCF * CFrame.fromAxisAngle(axis, angle)
-- case: point is to close, unreachable
-- return: push back planeCF so the "hand" still reaches, angles fully compressed
if l3 < math.max(l2, l1) - math.min(l2, l1) then
return planeCF * CFrame.new(0, 0, math.max(l2, l1) - math.min(l2, l1) - l3), -math.pi/2, math.pi
-- case: point is to far, unreachable
-- return: for forward planeCF so the "hand" still reaches, angles fully extended
elseif l3 > l1 + l2 then
return planeCF, math.pi/2, 0, l3
-- case: point is reachable
-- return: planeCF is fine, solve the angles of the triangle
else
local a1 = -math.acos((-(l2 * l2) + (l1 * l1) + (l3 * l3)) / (2 * l1 * l3))
local a2 = math.acos(((l2 * l2) - (l1 * l1) + (l3 * l3)) / (2 * l2 * l3))
return planeCF, a1 + math.pi/2, a2 - a1
end
end
local function SolveLegIK(originCFF, targetPos, l1, l2, C1Off)
-- build intial values for solving
local originCF = originCFF*CFrame.new(-C1Off.X,0,0)
local localized = originCF:pointToObjectSpace(targetPos)
local localizedUnit = localized.unit
local l3 = localized.magnitude
-- build a "rolled" planeCF for a more natural arm look
local axis = Vector3.new(0, 0, -1):Cross(-localizedUnit)
local angle = math.acos(-localizedUnit.Z)
local planeCF = originCF * CFrame.fromAxisAngle(axis, angle):Inverse()
-- case: point is to close, unreachable
-- return: push back planeCF so the "hand" still reaches, angles fully compressed
if l3 < math.max(l2, l1) - math.min(l2, l1) then
return planeCF * CFrame.new(0, 0, math.max(l2, l1) - math.min(l2, l1) - l3), -math.pi/2, math.pi
-- case: point is to far, unreachable
-- return: for forward planeCF so the "hand" still reaches, angles fully extended
elseif l3 > l1 + l2 then
return planeCF, math.pi/2, 0, l3
-- case: point is reachable
-- return: planeCF is fine, solve the angles of the triangle
else
local a1 = -math.acos((-(l2 * l2) + (l1 * l1) + (l3 * l3)) / (2 * l1 * l3))
local a2 = math.acos(((l2 * l2) - (l1 * l1) + (l3 * l3)) / (2 * l2 * l3))
return planeCF, math.pi/2-a1, -(a2 - a1)
end
end
local function SolveLesIK(o,t,l0,l1) -- Does the major math calculations for IK
-- Make the position local relative to the origin
local l = o:pointToObjectSpace(t) -- World space to local space
local lu = l.Unit -- Get normalized unit for future math
local m = l.Magnitude -- Get the length from the position to the target
-- Make a CFrame pointing from the shoulder position directing to the second position
local x = Vector3.new(0,0,-1):Cross(-lu) -- Cross the forward vector with the negative of the normalized unit
local g = math.acos(-lu.Z) -- Get the arc-cosine of the negative normalized unit
local p = o*CFrame.fromAxisAngle(x,g):Inverse() -- Get the IK plane
-- In a self.RightRotationAngle-triangle, we have the hypotenuse and the two shorter legs.
-- In a self.RightRotationAngle triangle, the hypotenuse is side "c," and the legs are a and b.
-- This information will be helpful later on.
if m < math.max(l1,l0)-math.min(l1,l0) then
-- If c is between the lengths of a and b then return an offsetted plane so that one of the lengths reaches the goal,
-- but the other length is folded so it looks natural
-- This cacluation is done when a position comes before the end of the leg, and may look a bit... odd
return p*CFrame.new(0,0,math.max(l1,l0)-math.min(l1,l0)-m),-math.pi/2,math.pi
elseif m > l0+l1 then
-- If c > a + b then return flat angles and an offsetted plane which reaches its target
-- Basically, this makes the leg flat if there is nothing to place it on
return p,math.pi/2,0
else
-- Otherwise, use the law of cosines
-- This is going to be all cases where the leg actually bends
local a1 = -math.acos((-(l1*l1)+(l0*l0)+(m*m))/(2*l0*m))
local a2 = math.acos(((l1*l1)-(l0*l0)+(m*m))/(2*l1*m))
return p,math.pi/2-a1,-(a2-a1)
end
end
local function WorldCFrameToC0ObjectSpace(motor6DJoint,worldCFrame)
local part1CF = motor6DJoint.Part1.CFrame
local part0 = motor6DJoint.Part0
local c1Store = motor6DJoint.C1
local c0Store = motor6DJoint.C0
local relativeToPart0 = part0.CFrame:inverse() * worldCFrame * c1Store
local goalC0CFrame = relativeToPart0
return goalC0CFrame
end
local function WorldCFrameToC1ObjectSpace(motor6DJoint,worldCFrame)
local relativeToPart0 = worldCFrame:Inverse() * motor6DJoint.Part0.CFrame * motor6DJoint.C0
local goalC0CFrame = relativeToPart0
return goalC0CFrame
end
local R6IK = {}
R6IK.__index = R6IK
function R6IK.New(Character)
local self = {}
self.Torso = Character.Torso
self.HumanoidRootPart = Character.HumanoidRootPart
self.LeftArm = Character["Left Arm"]
self.RightArm = Character["Right Arm"]
self.LeftLeg = Character["Left Leg"]
self.RightLeg = Character["Right Leg"]
self.Motor6Ds = {
["Left Shoulder"] = self.Torso["Left Shoulder"],
["Right Shoulder"] = self.Torso["Right Shoulder"],
["Left Hip"] = self.Torso["Left Hip"],
["Right Hip"] = self.Torso["Right Hip"],
["RootJoint"] = self.HumanoidRootPart["RootJoint"]
}
self.C0s = {
["Left Shoulder"] = self.Motor6Ds["Left Shoulder"].C0,
["Right Shoulder"] = self.Motor6Ds["Right Shoulder"].C0,
["Left Hip"] = self.Motor6Ds["Left Hip"].C0,
["Right Hip"] = self.Motor6Ds["Right Hip"].C0,
["RootJoint"] = self.Motor6Ds["RootJoint"].C0
}
self.C1s = {
["Left Shoulder"] = self.Motor6Ds["Left Shoulder"].C1,
["Right Shoulder"] = self.Motor6Ds["Right Shoulder"].C1,
["Left Hip"] = self.Motor6Ds["Left Hip"].C1,
["Right Hip"] = self.Motor6Ds["Right Hip"].C1,
["RootJoint"] = self.Motor6Ds["RootJoint"].C1
}
self.Part0s = {
["Left Shoulder"] = self.Motor6Ds["Left Shoulder"].Part0,
["Right Shoulder"] = self.Motor6Ds["Right Shoulder"].Part0,
["Left Hip"] = self.Motor6Ds["Left Hip"].Part0,
["Right Hip"] = self.Motor6Ds["Right Hip"].Part0,
["RootJoint"] = self.Motor6Ds["RootJoint"].Part0
}
self.Part1s = {
["Left Shoulder"] = self.Motor6Ds["Left Shoulder"].Part1,
["Right Shoulder"] = self.Motor6Ds["Right Shoulder"].Part1,
["Left Hip"] = self.Motor6Ds["Left Hip"].Part1,
["Right Hip"] = self.Motor6Ds["Right Hip"].Part1,
["RootJoint"] = self.Motor6Ds["RootJoint"].Part1
}
self.LeftUpperArmLength = 1
self.LeftLowerArmLength = 1
self.RightUpperArmLength = 1
self.RightLowerArmLength = 1
self.LeftUpperLegLength = 1
self.LeftLowerLegLength = 1
self.RightUpperLegLength = 1
self.RightLowerLegLength = 1
self.TorsoIK = false
return setmetatable(self, R6IK)
end
function R6IK:ArmIK(Side : "Left" | "Right", Position)
if Side == "Left" then
local OriginCF = self.Torso.CFrame*self.C0s["Left Shoulder"]
local C1Off = self.C1s["Left Shoulder"]
local PlaneCF,ShoulderAngle,ElbowAngle, l3 = SolveArmIK(OriginCF, Position, self.LeftUpperArmLength, self.LeftLowerArmLength, C1Off, Side)
local ShoulderAngleCFrame, ElbowAngleCFrame = CFrame.Angles(ShoulderAngle, 0, 0), CFrame.Angles(ElbowAngle, 0, 0)
local ShoulderCF = PlaneCF * ShoulderAngleCFrame*CFrame.new(0,-self.LeftUpperArmLength * 0.5,0)
local ElbowCF = ShoulderCF*CFrame.new(0,-self.LeftUpperArmLength * 0.5,0)* ElbowAngleCFrame * CFrame.new(0, -self.LeftLowerArmLength*0.5, 0)*CFrame.new(0,(self.LeftArm.Size.Y-self.LeftLowerArmLength)*0.5,0)
self.Motor6Ds["Left Shoulder"].C1 = WorldCFrameToC1ObjectSpace(self.Motor6Ds["Left Shoulder"], ElbowCF)
elseif Side == "Right" then
local OriginCF = self.Torso.CFrame*self.C0s["Right Shoulder"]
local C1Off = self.C1s["Right Shoulder"]
local PlaneCF,ShoulderAngle,ElbowAngle, l3 = SolveArmIK(OriginCF, Position, self.RightUpperArmLength, self.RightLowerArmLength, C1Off, Side)
local ShoulderAngleCFrame, ElbowAngleCFrame = CFrame.Angles(ShoulderAngle, 0, 0), CFrame.Angles(ElbowAngle, 0, 0)
local ShoulderCF = PlaneCF * ShoulderAngleCFrame*CFrame.new(0,-self.RightUpperArmLength * 0.5,0)
local ElbowCF = ShoulderCF*CFrame.new(0,-self.RightUpperArmLength * 0.5,0)* ElbowAngleCFrame * CFrame.new(0, -self.RightLowerArmLength*0.5, 0)*CFrame.new(0,(self.RightArm.Size.Y-self.RightLowerArmLength)*0.5,0)
self.Motor6Ds["Right Shoulder"].C1 = WorldCFrameToC1ObjectSpace(self.Motor6Ds["Right Shoulder"], ElbowCF)
end
end
function R6IK:LegIK(Side : "Left" | "Right", Position)
if Side == "Left" then
local OriginCF = self.Torso.CFrame*self.C0s["Left Hip"]
local C1Off = self.C1s["Left Hip"]
local PlaneCF,ShoulderAngle,ElbowAngle, l3 = SolveLegIK(OriginCF*CFrame.Angles(0, math.pi/2, 0), Position, self.LeftUpperLegLength, self.LeftLowerLegLength, C1Off)
local HipAngleCFrame, KneeAngleCFrame = CFrame.Angles(ShoulderAngle, 0, 0), CFrame.Angles(ElbowAngle, 0, 0)
local HipCF = PlaneCF * HipAngleCFrame*CFrame.new(0,-self.LeftUpperLegLength * 0.5,0)
local KneeCF = HipCF*CFrame.new(0,-self.LeftUpperLegLength * 0.5,0)* KneeAngleCFrame * CFrame.new(0, -self.LeftLowerLegLength*0.5, 0)*CFrame.new(0,(self.LeftLeg.Size.Y-self.LeftLowerLegLength)*0.5,0)
self.Motor6Ds["Left Hip"].C0 = WorldCFrameToC0ObjectSpace(self.Motor6Ds["Left Hip"], KneeCF)
elseif Side == "Right" then
local OriginCF = self.Torso.CFrame*self.C0s["Right Hip"]
local C1Off = self.C1s["Right Hip"]
local PlaneCF,ShoulderAngle,ElbowAngle, l3 = SolveLegIK(OriginCF*CFrame.Angles(0, -math.pi/2, 0), Position, self.RightUpperLegLength, self.RightLowerLegLength, C1Off)
local HipAngleCFrame, KneeAngleCFrame = CFrame.Angles(ShoulderAngle, 0, 0), CFrame.Angles(ElbowAngle, 0, 0)
local HipCF = PlaneCF * HipAngleCFrame*CFrame.new(0,-self.RightUpperLegLength * 0.5,0)
local KneeCF = HipCF*CFrame.new(0,-self.RightUpperLegLength * 0.5,0)* KneeAngleCFrame * CFrame.new(0, -self.RightLowerLegLength*0.5, 0)*CFrame.new(0,(self.RightLeg.Size.Y-self.RightLowerLegLength)*0.5,0)
self.Motor6Ds["Right Hip"].C0 = WorldCFrameToC0ObjectSpace(self.Motor6Ds["Right Hip"], KneeCF)
end
end
return R6IK
That’s literally all since the animation is played externally out of this (obviously)