CFrame Movement Laggy

MapleMarvel · March 16, 2018, 6:06pm

So I am moving some models using SetPrimaryPartCFrame, but have discovered that it is somewhat laggy when I move the models with enough speed. Is there a better alternative to move models around without getting choppy / laggy movement?

Notes:

The models are moved via a server script since they are server side objects that are being moved.
I need fairly precise movement and speed, which is why I am using CFrames to move models in the first place.

ckdevver · March 16, 2018, 6:09pm

It has nothing to do with SetPrimaryPartCFrame, it probably has to do with the loop you’re using to move it, send some code please, that’s really what we need, not to mention the fact that since it’s on the server, it won’t update at 60 fps for the players, since the server can’t send to the player and the player can’t receive every frame.

sleitnick · March 16, 2018, 6:09pm

If you’re moving via CFrame and want to do it smoothly, then you need to do it with RenderStep, but that has to happen on the client.

If moving on the server, then utilize the physics engine (e.g. body movers), which the clients will then properly interpolate in-game as the server replicates the changes.

gillern · March 16, 2018, 6:20pm

I think Heartbeat is the proper thing to use, RenderStepped is only supposed to be used for camera stuff afaik.

You could do something like

RunService.Heartbeat:Connect(function(d)
 model:SetPrimaryPartCFrame(model:GetPrimaryPartCFrame():lerp(whateverCFrameYouWant, d*10))
end)

And that will move it smoothly enough. You can change d*10 to change how fast you want it to move

Kiansjet · March 16, 2018, 6:24pm

Don’t use SetPrimaryPartCFrame. Just weld constraint all the parts to the primary part and set the primary part’s CFrame.

Luaction · March 16, 2018, 6:25pm

The server can only send updates to the clients at 20Hz (or 20 times per second) which is why you get the choppy movement when cframing on the server.

As the others have said, either use bodymovers to move your objects (in which case the physics engine will interpolate the positions for you) or you CFrame the objects yourself on the clients.

sleitnick · March 16, 2018, 7:15pm

If you want something to be smooth, then it needs to be synced to when the camera updates. If it’s out of sync with rendering (i.e. the camera), then it won’t look smooth.

Ideally I wouldn’t want to move a whole model continuously on renderstep, but it would at least make it look smooth

gillern · March 16, 2018, 7:30pm

That’s why I added in the damping, it’s a good balance of performance and looks.

I used it in a new game of mine too, so I just move the entire model using a custom “SetPrimaryPartCFrame” function and put it inside Heartbeat so the parts in it don’t start getting dislocated relative to the primary part.

MapleMarvel · March 16, 2018, 8:24pm

Is Heartbeat something that can be run in a server script, or does it need to be in a local script?

Kiansjet · March 16, 2018, 8:44pm

Pretty sure everything but render step fires serverside.

Kampfkarren · March 16, 2018, 9:02pm

This is correct. The server doesn’t need to render anything, but it does have normal steps and heartbeats.

Corecii · March 16, 2018, 9:09pm

This reply I made to a previous post is relevant.

Here it is quoted:

Example

Code:

local model = workspace.Model

local angle = 0

while true do
	for i = 1, 100 do  -- repeat 100 time to exaggerate the effect so it can be seen in a 30 sec video
		model:SetPrimaryPartCFrame(CFrame.new(0, 10, 0)*CFrame.Angles(0, math.rad(angle), 0))
		angle = (angle + 0.1)%360
	end
	wait()
end

Best way to smoothly move a model?

If you want to move this with physics, then you’ll want a joint structure like this
Root Part (Unanchored)
    Weld -> Model Parts (Unanchored)
If you want to move this with scripts and setting CFrame on Heartbeat, then you’ll want a joint structure like this
Root Part (Anchored)
    Motor6D -> Base Part (Unanchored)
        Weld -> Model Parts (Unanchored)
When you move the Root Part, all of the other parts will move too.

Key point with the latter one is that the Motor6D lets you move the anchored Root Part and have the rest of the unanchored parts move with it. If you use a Weld with an anchored Root instead of a Motor6D, then the Model Parts will not move when the Root does.

If you want this to look as smooth as possible to clients, you’ll need to either:

Use physics. Roblox makes this smooth when going from server → client automatically.

Set the CFrame on the client. This removes any latency or “network lag”, and has a higher update rate than the network send rate.

Optionally set the CFrame on RenderStepped. This will be “as smooth as possible” but isn’t necessary for it to be smooth.

Most of this response was taken from here.

I also made a really long post with various examples of how to set up and move models, including place file examples you can inspect and mess with:

Ultimately you’ll either need to use physics or set the CFrame on the client. If you set the CFrame from the server, you’ll be updating it at 20 times a second but the framerate will be 60 times a second so it will be choppy. That might be a fair tradeoff though, if using physics or setting the CFrame on the client is not possible.

If anyone goes this route, the most important part is the custom “SetPrimaryPartCFrame” function. Whether you move things on Heartbeat or Stepped or RenderStepped or just in a loop with wait() doesn’t matter. If you use the built in SetPrimaryPartCFrame then parts will drift over time. If you use a custom one that saves the offsets between parts at the beginning then the parts won’t drift.