Spinning cubes for OpenComputers

local component = require("component")
local event = require("event")
local math = require("math")
local os = require("os")

-- Initialize variables
local A, B, C = 0, 0, 0
local cubeWidth = 20
local width, height = 160, 44
local zBuffer = {}
local buffer = {}
local backgroundASCIICode = '.'
local distanceFromCam = 100
local horizontalOffset
local K1 = 40
local incrementSpeed = 0.6

-- Initialize the screen
local screen = component.gpu

-- Function to clear the screen
local function clearScreen()
    screen.fill(1, 1, width, height, backgroundASCIICode)
end

-- Function to calculate X coordinate
local function calculateX(i, j, k)
    return j * math.sin(A) * math.sin(B) * math.cos(C) - k * math.cos(A) * math.sin(B) * math.cos(C) +
           j * math.cos(A) * math.sin(C) + k * math.sin(A) * math.sin(C) + i * math.cos(B) * math.cos(C)
end

-- Function to calculate Y coordinate
local function calculateY(i, j, k)
    return j * math.cos(A) * math.cos(C) + k * math.sin(A) * math.cos(C) -
           j * math.sin(A) * math.sin(B) * math.sin(C) + k * math.cos(A) * math.sin(B) * math.sin(C) -
           i * math.cos(B) * math.sin(C)
end

-- Function to calculate Z coordinate
local function calculateZ(i, j, k)
    return k * math.cos(A) * math.cos(B) - j * math.sin(A) * math.cos(B) + i * math.sin(B)
end

-- Function to calculate for surface
local function calculateForSurface(cubeX, cubeY, cubeZ, ch)
    local x = calculateX(cubeX, cubeY, cubeZ)
    local y = calculateY(cubeX, cubeY, cubeZ)
    local z = calculateZ(cubeX, cubeY, cubeZ) + distanceFromCam

    local ooz = 1 / z
    local xp = math.floor(width / 2 + horizontalOffset + K1 * ooz * x * 2)
    local yp = math.floor(height / 2 + K1 * ooz * y)

    local idx = xp + yp * width
    if idx >= 0 and idx < width * height then
        if not zBuffer[idx] or ooz > zBuffer[idx] then
            zBuffer[idx] = ooz
            buffer[idx] = ch
        end
    end
end

-- Main loop
while true do
    clearScreen()
    zBuffer = {}
    buffer = {}

    -- First cube
    cubeWidth = 20
    horizontalOffset = -2 * cubeWidth
    for cubeX = -cubeWidth, cubeWidth, incrementSpeed do
        for cubeY = -cubeWidth, cubeWidth, incrementSpeed do
            calculateForSurface(cubeX, cubeY, -cubeWidth, '@')
            calculateForSurface(cubeWidth, cubeY, cubeX, '$')
            calculateForSurface(-cubeWidth, cubeY, -cubeX, '~')
            calculateForSurface(-cubeX, cubeY, cubeWidth, '#')
            calculateForSurface(cubeX, -cubeWidth, -cubeY, ';')
            calculateForSurface(cubeX, cubeWidth, cubeY, '+')
        end
    end

    -- Second cube
    cubeWidth = 10
    horizontalOffset = 1 * cubeWidth
    for cubeX = -cubeWidth, cubeWidth, incrementSpeed do
        for cubeY = -cubeWidth, cubeWidth, incrementSpeed do
            calculateForSurface(cubeX, cubeY, -cubeWidth, '@')
            calculateForSurface(cubeWidth, cubeY, cubeX, '$')
            calculateForSurface(-cubeWidth, cubeY, -cubeX, '~')
            calculateForSurface(-cubeX, cubeY, cubeWidth, '#')
            calculateForSurface(cubeX, -cubeWidth, -cubeY, ';')
            calculateForSurface(cubeX, cubeWidth, cubeY, '+')
        end
    end

    -- Third cube
    cubeWidth = 5
    horizontalOffset = 8 * cubeWidth
    for cubeX = -cubeWidth, cubeWidth, incrementSpeed do
        for cubeY = -cubeWidth, cubeWidth, incrementSpeed do
            calculateForSurface(cubeX, cubeY, -cubeWidth, '@')
            calculateForSurface(cubeWidth, cubeY, cubeX, '$')
            calculateForSurface(-cubeWidth, cubeY, -cubeX, '~')
            calculateForSurface(-cubeX, cubeY, cubeWidth, '#')
            calculateForSurface(cubeX, -cubeWidth, -cubeY, ';')
            calculateForSurface(cubeX, cubeWidth, cubeY, '+')
        end
    end

    -- Render the buffer
    for k = 0, width * height - 1 do
        if buffer[k] then
            screen.set(k % width + 1, math.floor(k / width) + 1, buffer[k])
        end
    end

    -- Update angles
    A = A + 0.05
    B = B + 0.05
    C = C + 0.01

    os.sleep(0.016)  -- Sleep for approximately 16ms (60 FPS)
end