Unit vectors multiplied by a number returns another vector with a different direction

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1

Using bodymovers to move parts.

-- vec3 being the target to reach
-- obj being the Instance
-- self.speed being 10
local v = (vec3 - obj.Position) *Vector3.new(1, 0, 1)
local timeNeeded = v.Magnitude/self.speed

obj.BodyVelocity.Velocity = v.Unit * self.speed

wait(timeNeeded)
obj.BodyVelocity.Velocity = Vector3.new(0, 0, 0)
-- finished

Ideally it would head towards vec3 at a speed of 10 studs per second.
https://gyazo.com/6ca68d753571970b91835c298d60fa06
^ What the code snippet does

https://gyazo.com/85b9418cee74d7901f7ec64d44df1faa
^ If I have the BodyVelocity’s velocity to be simply just the unit vector and not multiply it.
It maintains its direction but of course at a slower speed.

Solved.

Issue was that the part was dragging along the floor.

2

There is nothing incorrect about your vector calculations (although I’m not sure it would reach the target every time).

I’ve just created a reproduction in Studio and experienced no issue at all. Let me know if you see any differences. I placed a BodyVelocity inside of Part with all default values.

local v = (workspace.Goal.Position - workspace.Part.Position)*Vector3.new(1, 0, 1)
local timeNeeded = v.Magnitude/10

workspace.Part.BodyVelocity.Velocity = v.Unit * 10

wait(timeNeeded)
workspace.Part.BodyVelocity.Velocity = Vector3.new(0, 0, 0)

This repro goes in the correct direction every single time, so I think the problem exists outside of your math but I am not sure where.

One alternative (and this is what I do for my classed AI units), is to use CFrame a little bit instead like so (and you can obviously switch to BodyVelocity):

local Goal = workspace.Goal
local Part = workspace.Part
local ImpulseStrength = 15

Part.CFrame = CFrame.new(Part.Position, Goal.Position)

while (Goal.Position - Part.Position).magnitude > 5 do
	Part:ApplyImpulse(Part.CFrame.LookVector * ImpulseStrength) wait()
end

Part.AssemblyLinearVelocity = Vector3.new(0,0,0)
1 Like
3

Thanks for the reply!
Theoretically it should have worked, hence I was confused.
But the issue was that the part was dragging along the ground(?)
Set the Y value to 5 to get it off the ground and indeed it maintained its direction.

Regarding CFrames, they are the equivalent to what I was doing with the vectors. But it was still appreciated! <3

1 Like