Code review on frame rate counter

Help and Feedback Code Review
#1 
--// Fps Counter

local RunService = game:GetService("RunService")

local FPS = 0

local function updateFPS()
	FPS += 1
end

RunService.RenderStepped:Connect(updateFPS)

while wait(1) do
	print(FPS)
	FPS = 0
end

--[[ Logic:

Reseting the variable 'FPS' back to 0 once it prints it because we 

don't want it to gain a number every render stepped event. A Player

won't notice the 'FPS' suddenly going down since render stepped fires every frame

and a frame fires every second and that's why there is a wait of 1 second on the while loop.


]]

Alright, so here’s what I want reviewed.

The Logic of the script that is commented and the overall script.

#2

To base it off the delta time (and get a little more accurate) you should do 1/dt

local function updateFPS(dt)
    FPS = math.floor(1/dt)
end

No need for any incrementing.

4 Likes
#5

That’s a wrong assumption, += and -= are new compounds.

#6

I just realized, thanks for pointing that out.

#7

cc @SilentsReplacement

I believe with this in mind, the script could just become this:

local RunService = game:GetService("RunService")

while true do
  wait(1)
  local dt = RunService.RenderStepped:Wait()
  local fps = math.floor(1 / dt)
  print(fps)
end

This way it minimizes the amount of implicit state.

2 Likes
#8

I find heartbeat the best solution, since it fires every frame after physics simulation.

Looking at your script, well delta time can be sometimes different resulting in in-accurate FPS. So the best solution I find is just divide by 1.

Here’s so if you would like to review my script.

local RunService = game:GetService("RunService")

local frames = 0

RunService.Heartbeat:Connect(function()
      frames += 1
end)

while wait(1) do
     script.Parent.Text = math.floor(frames / 1)
end

However, delta time would be a little more accurate since it’s the time elapsed since the last frame and you can just divide the delta time by 1.

1 Like
#9

With this in mind, now knowing you want the average FPS, you can display it like so:

local RunService = game:GetService("RunService")

-- How many seconds should pass before the FPS counter is updated. Set to 0
-- to have the counter update on every frame.
local MINIMUM_DISPLAY_DELAY_IN_SECONDS = 1

local frame = 0
local timeElapsed = 0

RunService.Heartbeat:Connect(function(step)
  frame += 1
  timeElapsed += step

  if timeElapsed >= MINIMUM_DISPLAY_DELAY_IN_SECONDS then
    local fps = frame / timeElapsed
    script.Parent.Text = math.floor(fps)

    frame = 0
    timeElapsed = 0
  end
end)
2 Likes