Making ambient shift to RGB instead of instant?

hey, I don't have experience with lighting so this code may be incorrect, but I'm fairly certain the general concept will have to be loop that changes the rgb values overtime. I found a nice looking method on the Color3 documentation called Color3:lerp().

local function shiftTint(rgbStart, rgbEnd, time)
    for alpha = 0, 1, 1 / (time * 10) do
        Color.TintColor = rgbStart:lerp(rgbEnd, alpha)
        wait(0.1)
    end
end

time will be the transition time in seconds. I haven't tested it so let me know if there's a problem

edit: PS, you should be using local when declaring variables even on the outside, it's neater :)

edit 2: from what I see, your brightness is dependent on time while your color is not, so it seems wasteful to create a new color every time. what I would do is make a variable that shows the time of day. every loop, you will check the time passed, and once it reaches your threshold, change that value to something like "night", "day", etc. this has the bonus of making it easier to understand.

if your time was in fact changed, this is where you run that function I gave you earlier, using the current tint and the new tint.

after all that, calculate your brightness like you did already, depending on the time of day. I would make an object to organize the data for each time of day. here's what I would do. (remember, haven't used lighting before so I can't optimize everything :) )

function shiftTint(rgbStart, rgbEnd, time)
    for alpha = 0, 1, 1 / (time * 10) do
        Color.TintColor = rgbStart:lerp(rgbEnd, alpha)
        wait(0.1)
    end
end

local Settings = {
    Night = {
        Tint = Color3.fromRGB (192, 44, 255),
        Brightness = function(t) return t / 180 * -0.2 end
    },
    Day = {
        Tint = Color.TintColor = Color3.fromRGB (144, 144, 144),
        Brightness = function(t) return -(0.8 - t / 180 * 0.2) end
    },
    Default = {
        Tint = Color3.fromRGB (192, 44, 255),
        Brightness = function(t) return -0.2 end
    }
}

local setting = Settings.Default
local LOOPTIME = 0.05
local MINS_PER_DAY = 60 * 24
local time = game.Lighting:GetMinutesAfterMidnight()

while true do
    -- now you only need to get the time once; the old time is added to and reused
    time = (time + minutesPerSecond * LOOPTIME) % MINS_PER_DAY
    game.Lighting:SetMinutesAfterMidnight(time)

    if RealisticDarkness == true and (time >= 1080 or time <= 360) then
        minsPastSix = time - 1080
        if minsPastSix < 0 then
            minsPastSix = 360 + time
        end

        local newSetting -- decide the current setting
        if minsPastSix <= 180 then
            newSetting = Settings.Night
        elseif MinsPastSix >= 540 then
            newSetting = Settings.Day
        else
            newSetting = Settings.Default
        end

        if setting ~= newSetting then -- transition the color if changed
            shiftTint(setting.Tint, newSetting.Tint, 3)
            setting = newSetting
        end

        Color.Brightness = setting.Brightness(time) -- adjsut brightness
    end
    wait(LOOPTIME)
end

also, I think that the people in the comments had a better solution that I did. tweenservice is built for smooth transitions, and I expect it works on color too (I didn't know that when I posted). my solution is a bit hackier, so I suggest you look into tweenservice as well :)