Lua Utility Functions

The Defoldmine
19

Hmm. That looks interesting. It’s definitely not a “LERP” since that’s a linear interpolation and the result here is not linear. More rather it’s sort-of like a low-pass filter, as in a function that always tends towards the target (if you take its limit), but “lags behind” a bit hence cutting off any abrupt movements (higher frequencies). I’m happy to see I’m not the only one using low pass filters for animation, yay!

I use this version lifted off the Wikipedia article on low pass filters:

-- @tparam number cutoff_frequency The cut-off frequency (in Hz) of the filter.
-- @treturn LowPassFilter The new filter function.
function M.low_pass(cutoff_frequency)
  local RC = 1.0 / (cutoff_frequency * 2.0 * math.pi);
  return function (previous_output, input, dt)
    local alpha = dt / (dt + RC);
    return previous_output + alpha * (input - previous_output);
  end
end
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