Fireworks 2.0

local color = {colors.red, colors.orange, colors.yellow, colors.white, colors.lightGray, colors.gray}
local refresh = 0.05
local frequency = 10
local text = {"<Enter Loading Text Here>", colors.lime}
local background = colors.black
local rainbowColors = true
-- change any of the above values to alter the look of the fireworks
term.setBackgroundColor(colors.black)
term.clear()
local fw = {}
local x, y = term.getSize()
color = rainbowColors and {
    {colors.red, colors.orange, colors.yellow, colors.white};
    {colors.green, colors.lime, colors.yellow, colors.white};
    {colors.blue, colors.cyan, colors.lightBlue, colors.white};
    {colors.purple, colors.magenta, colors.pink, colors.white};
} or color
local len = rainbowColors and #color[1] or #color
if rainbowColors then
    for i, t in ipairs(color) do
        t[#t + 1] = background
    end
else
    color[#color + 1] = background
end
local advance = function()
    for k, t in pairs(fw) do
        t[2] = t[3] == 1 and (t[2] + 0.5) or (t[2] - 1)
        t = t[3] == 1 and (t[2] <= (y + len) and t or nil) or (t[2] >= 1 - len and t or nil)
    end
end
local render = function()
    for k, t in pairs(fw) do
        for i = 1, len + 1 do
            if t[2] - i >= 1 then
                term.setCursorPos(t[1], math.floor(t[2]) - i)
                term.setTextColor(t[3] == 1 and (rainbowColors and color[t[4]][i] or color[i]) or (rainbowColors and color[t[4]][len + 2 - i] or color[i]))
                term.write(t[3] == 1 and (t[2] % 1 == 0 and "-" or "_") or string.char(166))
            end
        end
    end
    term.setCursorPos((x - #text[1]) / 2, y / 2)
    term.setTextColor(text[2])
    for char in text[1]:gmatch(".") do
        if char ~=" " then
            term.write(char)
        else
            local xpos, ypos = term.getCursorPos()
            term.setCursorPos(xpos + 1, ypos)
        end
    end
end
local timer = os.startTimer(refresh)
while true do
    do
        local e = {os.pullEvent("timer")}
        if e[2] ~= timer then return end
        advance()
        if math.random(len / refresh / frequency) == 1 then
            local rand = math.random(2)
            fw[{}] = {math.random(x), rand == 1 and 0.5 or y + 1, rand, rainbowColors and math.random(#color) or nil}
        end
        render()
        timer = os.startTimer(refresh)
    end
end