How to tween/lerp a Bezier curve

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#1

As seen from a few posts that I find, the result I can get is either keep on stopping and continuing the tween, or use lerp which continuously changes the CFrame, which I don’t know, is how do you actually get the “Position” or CFrame of the certain point in the curve, as you need that point to tween/lerp to. From the Dev Hub i can find the formula, but the formula only returns a position value, which I don’t think can be used to do the curve, it will be appreciated to have a solution to this.Thanks.

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#2

Sorry, bit confused about what you’re asking.

Bezier functions usually take in a number from 0-1 that represents a percent along the curve:

local function QuadraticBezier(t, p0, p1, p2)
    local a = p0:Lerp(p1, t)
    local b = p1:Lerp(p2, t)
    return a:Lerp(b, t)
end

If you wanted to get the point at the start of that curve, you’d provide a t of 0.

If you wanted to get the point in the middle of that curve, you’d provide a t of 0.5, etc.

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Need help with a custom Tween Position
#3

sorry about my explanation, I know how the curve works, but what I dont know is how to make a tween/lerp thats moves along the curve. Thats why i want to find a certain “position” on the curve because i need to tween it to. Thanks

#4

I’m still a bit confused sorry. What are your inputs and what output do you want?

Maybe it would help if you said what you’re using this for at a higher level?

#5

I am basically trying to make a curve between 2 points(the bezier curve), and make an object move along that curve, using the gif you put above, i am trying to make the black dot that is moving along the curve. Sorry about my bad english i don’t have it as my first language. Thanks for helping. :slight_smile:

#6

Oh! All you have to do is move some value from 0 to 1 and compute the position.

I talk about it in this post:

(In that I call QuadraticBezier, which was defined earlier in that thread, to compute the position but you can substitute your own bezier function)

#7

I can understand what you mean by the post there, but the reason i am using this is to make a curved path for a vehicle to drive along, and because I use tween for straight lines, is there a way to keep on updating the tween in order to move along the curve? Or should i just stick to the one you mentioned above, Thanks for the help.

#8

Can you maybe share the code you’re using for straight paths, and we could translate it to use bezier?

#9

I actually attempted this a while back and can share my code hold on 1 second

#10

Ok here you go I made it into a model this version is actually cubic bezier which requires 4 points but you can easily change it to 3.

https://www.roblox.com/library/6696416877/Cubic-Bezier-model

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#11

I will take a look at that later, thanks for the help :slight_smile:

#12

Its just a basic tween to CFrame with {CFrame=part.CFrame} whereas part is the part to move to

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#13

You could change it to tween but as it’s in a loop it already looks smooth enough it depends on how fast you want the part to move.

#14

I have just taken a look at the model, and i kinda get what i needed. Thanks for you help, appreciated.

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