BodyVelocity/LinearVelocity acting weirdly on diagonals

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#1

(The red line is visualizing the part’s AssemblyLinearVelocity)

For some reason the AssemblyLinearVelocity of the part swings around, even though I’m just multiplying BodyVelocity.Velocity by -1.

Example:

The unusual behavior only happens on diagonals. When BodyVelocity.Velocity is perfectly aligned to an axis (eg. 20,0,0) it will behave as expected:

Any help with this is appreciated since I’m using BodyVelocity for a custom movement system and the effect is really noticeable.

It occurs with both BodyVelocity and LinearVelocity, and I need to solve this problem without increasing MaxForce or the mass of the part, as that would mess up other aspects of the movement.

Place used in the example videos:
velocity bug.rbxl (40.7 KB)
(ran as server only, there’s an attribute on the workspace which when clicked will reverse the BodyVelocity's velocity)

Linear velocity strafing problem
#2

What’s the code you’re using to set the velocity?

#3

sorry I’m late, roblox devforum decided to delay the notification for some reason

this script is in the BodyVelocity

workspace:GetAttributeChangedSignal("reverse"):Connect(function()
	if workspace:GetAttribute("reverse") then
		script.Parent.Velocity *= Vector3.new(-1,1,-1)
		workspace:SetAttribute("reverse",false)
	end
end)
#4

This flips velocity on the X and Z axes which I assume is what you want. The problem is that the flip is in world space. I assume you want it to always flip around a specific axis of the part, regardless of the part’s current rotation?

#5

I want the vector to just shrink to 0 and then start expanding like it does in the second video, but for some reason on diagonals it doesn’t do that.

#6

Its because the direction you’re flipping it changes when the part rotates. Do you want it to always flip through the part the same way?

#7

yeah, I want the velocity to reverse like it does in the second video but when facing any direction

#8

Have you tried this?

workspace:GetAttributeChangedSignal("reverse"):Connect(function()
	if workspace:GetAttribute("reverse") then
		script.Parent.Velocity *= -1
		workspace:SetAttribute("reverse",false)
	end
end)
#9

yeah, but its basically the same since I’m leaving the Y axis at 0

(come to think of it, I probably should have mentioned that :skull:)