local effectChannels = {
  bloom = Channel.keyframe().addKey(0, 0),
  vignette = Channel.keyframe().addKey(0, 0),
  chromatic = Channel.keyframe().addKey(0, 0),
  grain = Channel.keyframe().addKey(0, 0)
}

local postProcessing = PostProcessing
local effects = {
  bloom = postProcessing.Bloom,
  vignette = postProcessing.Vignette,
  chromatic = postProcessing.ChromaticAberration,
  grain = postProcessing.Grain
}

for _, effect in pairs(effects) do
  effect.enableEffect {'intensity'}
end

for effectName, effect in pairs(effects) do
  effect.intensity = effectChannels[effectName]
end

function applyEffect(effectChannel, timing, duration, intensity)
  effectChannel.addKey(timing, effectChannel.valueAt(timing))
  effectChannel.addKey(timing + duration, intensity)
end

addScenecontrol(
  'posteffect',
  {'effect', 'duration', 'intensity'},
  function(cmd)
      local effectName, timing, duration, intensity = cmd.args[1], cmd.timing, cmd.args[2], cmd.args[3]
      local effectChannel = effectChannels[effectName]
      if effectChannel then
          applyEffect(effectChannel, timing, duration, intensity)
      end
  end
)