Can I add more control points in a Bézier curve?

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#1

I want to make a part move like a swirl, so I tried doing it with Bézier curves, but I think I will need more than 1 control point of a Bézier curve. How can I do that?

Swirl:
image

Example with 2 control points:
P0 (Anchor Point)
P1 (Control Point)
P2 (Control Point)
P3 (Anchor Point)

Demonstration: https://i.gyazo.com/f7982ce558d0c3fdfd3d22fe2b9e18a0.gif

My code of 1 control point:

--[[ SERVICES ]]
local TweenService = game:GetService("TweenService")
local RunService = game:GetService("RunService")
--[[ VARIABLES ]]
local Step = script:FindFirstChild("Step")

local Part = script.Parent:FindFirstChild("Part")
local P0 = script.Parent:FindFirstChild("P0") -- Anchor Point
local P1 = script.Parent:FindFirstChild("P1") -- Control Point
local P2 = script.Parent:FindFirstChild("P2") -- Anchor Point
--[[ FUNCTIONS ]]
local function LinearInterpolation(a, b, step)
	return a * (1 - step) + b * step
end

local function DoQuadBezier(p0, p1, p2, step)
	local L1 = LinearInterpolation(p0, p1, step)
	local L2 = LinearInterpolation(p1, p2, step)
	local Result = LinearInterpolation(L1, L2, step)
	return Result
end
--[[ SOURCE ]]
wait(2)

local StepTween = TweenService:Create(Step, TweenInfo.new(4), {Value = 1})
StepTween:Play()

Step.Changed:Connect(function()
	local TweenAlphaValue = TweenService:GetValue(Step.Value, Enum.EasingStyle.Quart, Enum.EasingDirection.InOut)
	local NewPosition = DoQuadBezier(P0.Position, P1.Position, P2.Position, TweenAlphaValue)
	Part.Position = NewPosition
end)
1 Like
#2

Yes , but not with the function you do right now. The function you have is for quadratic bezier instead you could make a function which takes N amount of control points.

This is what I used for my train system :

local function Lerp(a,b,c)
	if typeof(a) ~= 'CFrame' then
		return a + (b-a) * c
	else
		return a:Lerp(b,c)
	end
end

local function Bezier(t,tbl)
	local lastLerped = tbl
	repeat
		local tempTbl = {}
		for i, v in ipairs(lastLerped) do
			if (#lastLerped-1) >= i then
				tempTbl[i] = Lerp(v, lastLerped[i+1], t)
			end
		end
		lastLerped = tempTbl
	until #lastLerped == 1
	return lastLerped[1]
end

Where t is the time and tbl is an array containing the starting point, control points and ending point
Example : {start,n1,n2,n3…,end}

2 Likes
#3

And it works no matter how many control points there are?

#4

Yes , it supports N amount of points.

1 Like
#5

Your function worked for me! But can you explain to me what you do in that function for my future knowledge? I tried to understand it myself, but I don’t know some things…

#6 
local v1, v2, v3, v4 = start, n1, n2, endpoint;

local v5 = v1:lerp(v2);
local v6 = v2:lerp(v3);
local v7 = v3:lerp(v4);

local v8 = v5:lerp(v6);
local v9 = v6:lerp(v7);

local result = v8:lerp(v9);

This is how it works basically the function just makes it dynamic and easy to use.

1 Like