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Disable Gravity for a Specific Part?

Asked by

4 years ago

I have a gun that creates and shoots out an unanchored bullet (so it can trigger the touched event when it hits certain destructible blocks). However, unanchoring it just causes it to fall through the ground almost immediately once it's fired due to gravity, so how can I disable it just for this one part (nothing else)?

Here're my current configs for the bullet:

1local bullet = Instance.new("Part")
2bullet.Name = "Bullet"
3bullet.Anchored = false
4bullet.CanCollide = false
5bullet.Massless = true
6bullet.Locked = true
7bullet.Parent = game.Workspace
8-- turn off gravity here

I couldn't find any tutorials on this, so any help would be appreciated :)

1 answer

Answered by

cowsoncows 951

4 years ago

Edited 4 years ago

What you would need to do is apply a force to the part that is equal but opposite to the force of gravity. To do this you can use a BodyMover like BodyForce, or one of the newer physics constraints like VectorForce, and, using Newton's Second Law we can figure out the force we need to apply.

Newton's second law states that F = ma.

We need to find F, so we must multiply mass (m) by acceleration (a).

Mass can be found with the Part:GetMass() function.

Acceleration can be found as a property of workspace, workspace.Gravity.

Therefore the force you must apply will have to be upwards, on the y axis, like so: VectorForce.Force = Vector3.new(0, Part:GetMass()*workspace.Gravity, 0) (Making sure that the VectorForce is set to apply the force in world space, not local space)

EDIT: An example, creating the attachment and VectorForce and applying the proper force

1local attachment = Instance.new("Attachment", bullet)
2local vectorForce = Instance.new("VectorForce")
3vectorForce.Force = Vector3.new(0, bullet:GetMass() * workspace.Gravity, 0)
4vectorForce.ApplyAtCenterOfMass = true
5vectorForce.RelativeTo = Enum.ActuatorRelativeTo.World
6vectorForce.Attachment0 = attachment
7vectorForce.Parent = bullet

Thanks -- this should work (I tried it with some other parts) but when I tried to put it in, it just showed me an error. Reminder that the bullet is massless and created as a new part(doesn't exist in the workspace when editing). Can you give me an example on how to do it by placing it the script I gave in the question? Bob4koolest 78 — 4y

I've edited my answer. Even though the bullet is massless, :GetMass() won't be 0, it will still have a mass. I'm not sure what parts of the physics engine Massless effects, but constraints aren't affected by it in this way, so this will still work. cowsoncows 951 — 4y

Disable Gravity for a Specific Part?

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