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✓ ANSWER ACCEPTED

How can I make Sine and Cosine waves move smoothly into different waves?

Asked 472 views1 answers

So when using sine and cosine, and switching between how powerful they are, there can be some jagged movement. The reason I am asking is because I am making a game where player input can change the power of the sine and cosine. I made a sample script to show what I mean and people can test (if you want to know what I mean):

local Part = script.Parent
local RS = game:GetService("RunService")


local sine
do
	local frequency
	local phase = 0
	sine = function(amplitude, newFrequency)
		local t = tick()
		if not frequency then
			frequency = newFrequency
		elseif math.abs(newFrequency - frequency) < 0.01 then
			local oldArgument = t*frequency + phase
			frequency = newFrequency
			phase = oldArgument - t*frequency
		end
		print("Sine : " .. (amplitude * math.sin(t*frequency + phase)))
		return amplitude * math.sin(t*frequency + phase)
	end
end


local frames = 0
math.randomseed(tick())
local targetframes = math.random(300, 900)
local cf = true


RS.Stepped:Connect(function()
	frames = frames + 1
	if frames == targetframes then
		frames = 0
		targetframes = math.random(300, 900)
		cf = not(cf)
	end
	if cf then
		Part.CFrame = CFrame.new(-2, 2.5, 10) * CFrame.new(0, (sine(0.3, 1.2)), 0)
	else
		Part.CFrame = CFrame.new(-2, 2.5, 10) * CFrame.new(0, (sine(0.5, 16)), 0)
	end
end)

However when the sine and cosine powers change, there can be some jagged movement, If anyone knows how to make the changes more smooth, it would be greatly appreciated! :)

AnonymousEdited

1 comment

0

more smooth = more steps, less change

Anonymous#

1 answer

✓ Accepted answer

Problem here, is that the argument of sine/cosine function changes dramatically once you change the frequency. What you actually want here, is to keep the current argument the same, yet it would change faster on the next iterations.

Fortunately, you can fix this by figuring out by how much the argument has changed for and correct it by adding that difference as sine/cosine function's phase.

That would look something like this:

-- At beginning phase would be 0
local oldArgument = frequency*t + phase
frequency = newFrequency
phase = oldArgument - frequency*t -- Phase is simply the difference between old and new sine function's argument

In order to use this in the way you're currently using it, you'd have to define few local variables, that would remember the phase and frequency of the last function call:

local sine
do -- Using do block, in order to hide "phase" and "frequency" variables from global scope
  local frequency
  local phase = 0

  function sine(amplitude, newFrequency)
    local t = tick()

    if not frequency then
      frequency = newFrequency
    elseif math.abs(newFrequency - frequency) < 0.01 then
      -- Frequency has changed, calculate phase
      local oldArgument = t*frequency + phase
      frequency = newFrequency
      phase = oldArgument - t*frequency
    end

    print("Sine : " .. (amplitude * math.sin(t*frequency + phase)))
    return amplitude * math.sin(t*frequency + phase)
  end
end

Don't have any options to test this, but it should do the job.

AnonymousPermalink

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