A way to set CFrame lookAt with an offset to the pivot?

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#1

Below is an image of a weapons system I am working on. The red cube is the intended point of aim and the orange cube is the current point of aim.

image
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The rotation of the humanoid root part is calculated simply by the X and Z coordinates of the mouse in 3D space.

(Prototype.MPos = Vector3 mouse position)

-- Character rotation
Prototype.Character.HumanoidRootPart.CFrame = CFrame.new(Prototype.Character.HumanoidRootPart.Position,Vector3.new(
    Prototype.MPos.X,
    Prototype.Character.HumanoidRootPart.Position.Y,
    Prototype.MPos.Z
))

The weapon does point directly forward.
The weapon points slightly to the left, but the problem still remains.

Is there a way to offset the the position where the rotation is applied (pivot) on the humanoid root part and how would I go about doing that?

EDIT:
I’m gonna go into a bit more detail, but this is kinda strange so I’m hoping people will understand what the goal is.

Lemme explain through an example:

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(i.e.) 
yellowObj.CFrame = CFrame.new(yellowObj.CFrame.Position, vector3ToLookAt)

the yellow part would normally apply the rotation of the lookAt position in the centre of the object…

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I need to move the position where the lookAt vector rotates the part (pivots) to another point on the part.

More specifically:

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The red dot is where the current pivot of lookAt is.

I need it here:

482×642 362 KB

Or an alternative to using the lookAt vector that achieves the same result with the same degree of accuracy.

#2

You can use lookat with pivoting if you do some offsetting.

Now, I’m assuming from your post you want to pivot and not acting like a point is the center.

Now, bear in mind I haven’t tested the following as much as I should have, so if there is a mistake in my logic, please call out.

local function pivoting_look_at(from, to, pivot_offset) 
	--[[ 
	Takes arguments: 
	CFrame (object to create CFrame from), 
	Vector3 (Point that the new CFrame will look at),
	Vector3 (The pivot point in relation to from.)
	
	Returns: CFrame that is looking at the given point having pivoted around an offset.
	--]]

	assert(typeof(from)=="CFrame", "'pivoting_look_at': Invalid input for 'from'. It is a " .. typeof(from) .. ". Should be a CFrame") 
	assert(typeof(to)=="Vector3", "'pivoting_look_at': Invalid input for 'to'. It is a " .. typeof(to) .. ". Should be a Vector3.")
	assert(typeof(pivot_offset)=="Vector3", "'pivoting_look_at': Invalid input for 'pivot_offset', It is a " .. typeof(pivot_offset) .. ". should be a Vector3")
	
	
	local offsetfrom = from:ToWorldSpace(CFrame.new(pivot_offset))
	
	--[[Use the lookat CFrame creation with the offset position looking at
	the "Worldly" similar offset to-position.
	Effectively 'pivoting around a point']]--
	local ret = CFrame.new(offsetfrom.Position, to + offsetfrom.Position - from.Position)

	-- Return the pivoted center and not the pivoted pivot point.
	ret = ret:ToWorldSpace(CFrame.new(-pivot_offset))
	
	return ret
end

Using your yellowblock example, to achieve what you did you would use

yellowObj.CFrame = pivoting_look_at(yellowObj.CFrame, vector3ToLookAt, Vector3.new(0, -yellowObj.Size.Y/2, 0))
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#3

Thanks, the code works exactly how I needed it to.

1 Like