Simple function to achieve this effect:
local function fillUp(uiGradient, percent)
if percent <= .001 then
percent = 0
end
if percent == 0 or percent == 1 then
uiGradient.Transparency = NumberSequence.new(1-percent)
else
uiGradient.Transparency = NumberSequence.new({
NumberSequenceKeypoint.new(0, 0),
NumberSequenceKeypoint.new(percent-.001, 0),
NumberSequenceKeypoint.new(percent, 1),
NumberSequenceKeypoint.new(1, 1)
})
end
end