mandelbrot set for ComputerCraft

local Mandelbrot_Viewer_For_CraftOS = {}

local width, height = term.getSize()
local maxIterations = 1000
local xMin, xMax, yMin, yMax = -2, 1, -1, 1
local zoomFactor, moveSpeed = 0.8, 0.05
local centerX, centerY = 0, 0
local escapeRadius = 4
local colorMode = 1
local autoZoom = false

local colorPalette = {
    colors.white, colors.orange, colors.magenta, colors.lightBlue,
    colors.yellow, colors.lime, colors.pink, colors.gray,
    colors.lightGray, colors.cyan, colors.purple, colors.blue,
    colors.brown, colors.green, colors.red
}

local function map(x, y)
    local real = xMin + (xMax - xMin) * x / width
    local imag = yMin + (yMax - yMin) * y / height
    return real, imag
end

local function mandelbrot(cr, ci)
    local zr, zi, zr2, zi2 = 0, 0, 0, 0
    for i = 1, maxIterations do
        if zr2 + zi2 > escapeRadius then
            return i
        end
        zi = 2 * zr * zi + ci
        zr = zr2 - zi2 + cr
        zr2, zi2 = zr * zr, zi * zi
    end
    return maxIterations
end

local function getColor(iterations)
    if iterations == maxIterations then return colors.black end
    return colorPalette[(iterations % #colorPalette) + 1]
end

local function renderMandelbrot()
    for y = 1, height do
        for x = 1, width do
            local cr, ci = map(x, y)
            local iterations = mandelbrot(cr, ci)
            local color = getColor(iterations)
            term.setCursorPos(x, y)
            term.setBackgroundColor(color)
            term.write(" ")
        end
    end
end

local function zoom(factor, x, y)
    local cr, ci = map(x, y)
    local width, height = xMax - xMin, yMax - yMin
    xMin = cr - width * factor / 2
    xMax = cr + width * factor / 2
    yMin = ci - height * factor / 2
    yMax = ci + height * factor / 2
    centerX, centerY = cr, ci
end

local function move(dx, dy)
    local width, height = xMax - xMin, yMax - yMin
    local mx, my = dx * width * moveSpeed, dy * height * moveSpeed
    xMin, xMax = xMin + mx, xMax + mx
    yMin, yMax = yMin + my, yMax + my
    centerX, centerY = centerX + mx, centerY + my
end

function Mandelbrot_Viewer_For_CraftOS.run()
    local running = true
    local timer = os.startTimer(0.1)

    while running do
        renderMandelbrot()
        term.setCursorPos(1, 1)
        term.setBackgroundColor(colors.black)
        term.setTextColor(colors.white)
        term.write(string.format("Zoom: %.2e", 2 / (xMax - xMin)))

        local event, param1 = os.pullEvent()

        if event == "key" then
            if param1 == keys.space then zoom(zoomFactor, width / 2, height / 2)
            elseif param1 == keys.leftShift then zoom(1 / zoomFactor, width / 2, height / 2)
            elseif param1 == keys.left then move(-1, 0)
            elseif param1 == keys.right then move(1, 0)
            elseif param1 == keys.up then move(0, -1)
            elseif param1 == keys.down then move(0, 1)
            elseif param1 == keys.q then running = false
            elseif param1 == keys.c then
                colorMode = colorMode == 1 and 2 or 1
                colorPalette = colorMode == 1 and colorPalette or {unpack(colorPalette, 1, 8)}
            elseif param1 == keys.a then autoZoom = not autoZoom
            elseif param1 == keys.equals then maxIterations = math.min(maxIterations * 2, 10000)
            elseif param1 == keys.minus then maxIterations = math.max(100, maxIterations / 2)
            end
        elseif event == "timer" and param1 == timer then
            timer = os.startTimer(0.1)
            if autoZoom then zoom(0.99, width / 2, height / 2) end
        end
    end
end

term.clear()
print("Mandelbrot Viewer For CraftOS")
print("Arrow keys: Move")
print("Space/Shift: Zoom in/out")
print("C: Toggle color mode")
print("A: Toggle auto-zoom")
print("+/-: Increase/decrease detail")
print("Q: Quit")
sleep(2)
Mandelbrot_Viewer_For_CraftOS.run()