Car force towards the ground?

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#1

How can I make it so that the base gif the car or the wheels of the car are always exerting a force in the direction where the road is so that it always stays o the road, even if it’s upside down?

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#2

Use raycasting: WorldRoot | Roblox Creator Documentation, cause the return value RaycastResult | Roblox Creator Documentation yields ‘Normal’. You can check if a raycast hits the road and then see what normal it returns. This way, you can calculate a normal from your car to the road.

local raycastParams = RaycastParams.new()
raycastParams.FilterType = Enum.RaycastFilterType.Blacklist
raycastParams.FilterDescendantsInstances = {script.Parent}
raycastParams.IgnoreWater = true
 
-- Cast the ray
local carPrimaryPart = script.Parent.PrimaryPart

local TRACTION_FORCE = 10
local RAYCAST_LENGTH = 30

local function getTractionForce()
    local raycastNormal = -part.CFrame.UpVector
    local raycastResult = workspace:Raycast(
        part.Position,
        raycastNormal * RAYCAST_LENGTH,
        raycastParams
    )
    
    if raycastResult then
        -- Get the normal from the car to the road
    	local forceNormal = -(raycastResult.Normal - raycastNormal).Unit
    	return forceNormal * TRACTION_FORCE
    else
        -- You are not on a road
    	return Vector3.new()
    end
end
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#3

How will this help the car to always stay on the ground?

#4

You can add a VectorForce to your car and update it like this:

local runService = game:GetService('RunService')
local vectorForce = script.Parent.PrimaryPart.VectorForce

runService.Heartbeat:Connect(function()
    vectorForce.Force = getTractionForce()
end)

This force will try to make your car stick to the ground. I have not tested my code, but I think it might work. It is recommendable to set the center of force to the center of mass of your car to get rid of unwanted torque.

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#5

ok, so I add

this piece of code to the end of the first one?

Edit: If this works I’ll mark you as a solution

#6

Yes, but you have to correct the primary part related code. Also, I think that the TRACTION_FORCE is a bit low, so you might want to mess around with that.

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#7

I made a minor mistake in the forceNormal definition. / 2 should have been .Unit as edited.

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#8

I did some testing and I came up with this:
CarTraction.rbxl (33.0 KB)

Things to notice are:

  • Implementation of course
  • Improved friction of the wheels
  • You can drive upside down, which you can test with the half loop

The car is a bit… limited, but you can see my idea.

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#10

Please put this in #help-and-feedback:scripting-support

#11

Really? But this is physics related mainly

#12

Still involves scripting… So

#13

And it also involves physics, body thrust is physics, force is physics, but I guess it could be in either?

#14

Screenshot 2021-04-15 at 17.20.26

What is this part supposed to be?

The output says that I’m attempting to index nil with CFrame, are they supposed to be the wheels?

#15

Oh, no that is basically your primary part (car bottom, body or whatever you want to call it).

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