Super Mario FX Clone For Craft OS-PC ported to OpenComputers! (it's bad)

local component = require("component")
local event = require("event")
local gpu = component.gpu
local internet = require("internet")
local term = require("term")
local computer = require("computer")
local floor, cos, sin, abs = math.floor, math.cos, math.sin, math.abs

local loadingURL = "https://files.catbox.moe/l8tnog.bmp"
local bmpURL     = "https://files.catbox.moe/w9tlsn.bmp"
local playerURL  = "https://files.catbox.moe/fzau50.bmp"

local function download(url)
    local response = internet.request(url)
    if not response then error("Failed to download: " .. url) end
    local data = ""
    for chunk in response do data = data .. chunk end
    return data
end

local function stringUnpack(format, str, pos)
    local function unpackInt(str, pos, size, signed)
        local val = 0
        for i = 0, size - 1 do
            val = val + str:byte(pos + i) * (256 ^ i)
        end
        if signed and val >= 2^(size*8-1) then
            val = val - 2^(size*8)
        end
        return val, pos + size
    end
    if format == "<I4" then
        return unpackInt(str, pos, 4, false)
    elseif format == "<I2" then
        return unpackInt(str, pos, 2, false)
    elseif format == "BBB" then
        return str:byte(pos), str:byte(pos+1), str:byte(pos+2), pos+3
    else
        error("Unsupported format: " .. format)
    end
end

local function loadBMP(imageData)
    local width = stringUnpack("<I4", imageData, 19)
    local height = stringUnpack("<I4", imageData, 23)
    local bitsPerPixel = stringUnpack("<I2", imageData, 29)
    local compression = stringUnpack("<I4", imageData, 31)
    local dataOffset = stringUnpack("<I4", imageData, 11)
    if bitsPerPixel ~= 24 or compression ~= 0 then
        error("Unsupported BMP format. Only 24-bit uncompressed BMPs are supported.")
    end
    local texture = {}
    local rowSize = math.floor((bitsPerPixel * width + 31) / 32) * 4
    for y = 1, height do
        texture[y] = {}
        local rowStart = dataOffset + (height - y) * rowSize
        for x = 1, width do
            local pixelStart = rowStart + (x - 1) * 3
            local b, g, r = stringUnpack("BBB", imageData, pixelStart + 1)
            texture[y][x] = (r * 65536) + (g * 256) + b
        end
    end
    return texture, width, height
end

local function resizeBMP(bmp, origW, origH, newW, newH)
    local resized = {}
    for y = 1, newH do
        resized[y] = {}
        local srcY = math.floor((y-1) * origH / newH) + 1
        for x = 1, newW do
            local srcX = math.floor((x-1) * origW / newW) + 1
            resized[y][x] = bmp[srcY][srcX]
        end
        if y % 2 == 0 then os.sleep(0) end
    end
    return resized
end

local screenWidth, screenHeight = gpu.getResolution()

term.clear()
print("Downloading loading screen...")
local loadingImageData = download(loadingURL)
local loadingBMP, loadingW, loadingH = loadBMP(loadingImageData)
local loadingResized = resizeBMP(loadingBMP, loadingW, loadingH, screenWidth, screenHeight)
for y = 1, screenHeight do
    for x = 1, screenWidth do
        gpu.setBackground(loadingResized[y][x])
        gpu.set(x, y, " ")
    end
    if y % 2 == 0 then os.sleep(0) end
end

print("Downloading floor texture...")
local floorImageData = download(bmpURL)
os.sleep(0)
print("Downloading player sprite...")
local playerImageData = download(playerURL)
os.sleep(0)

local origFloorBMP, origFloorW, origFloorH = loadBMP(floorImageData)
os.sleep(0)
local bgWidth, bgHeight = 20, 20
local background = resizeBMP(origFloorBMP, origFloorW, origFloorH, bgWidth, bgHeight)
os.sleep(0)

local origPlayerBMP, origPlayerW, origPlayerH = loadBMP(playerImageData)
os.sleep(0)
local playerW, playerH = 8, 8
local playerSprite = resizeBMP(origPlayerBMP, origPlayerW, origPlayerH, playerW, playerH)
os.sleep(0)

local bufferIndex = gpu.allocateBuffer(screenWidth, screenHeight)
if not bufferIndex then error("Failed to allocate GPU buffer (not enough GPU RAM?)") end

local foclength, horizon, scale = 100, 15, 60
local camX, camY, camAngle = 10, 10, 0
local playerX, playerY = 10, 10
local jumpTime, jumpMax, isJumping, jumpVel = 0, 0.8, false, 0
local camZ = 0

local keyboard = component.isAvailable("keyboard") and require("keyboard") or nil
local keycodes = {w=17, a=30, s=31, d=32, space=57, q=16}

local lastTime = computer.uptime()
local frameCount = 0
local fps = 0

while true do
    frameCount = frameCount + 1
    local now = computer.uptime()
    if now - lastTime >= 1 then
        fps = frameCount
        frameCount = 0
        lastTime = now
    end

    gpu.setActiveBuffer(bufferIndex)
    gpu.setBackground(0x111133)
    gpu.fill(1, 1, screenWidth, screenHeight, " ")
    os.sleep(0)

    local halfW = screenWidth / 2
    local cosA, sinA = cos(camAngle), sin(camAngle)

    for y = horizon, screenHeight do
        local row = y - horizon
        local invRow = 1 / (row + 1 - camZ)
        for x = 1, screenWidth do
            local dx = x - halfW
            local dy = row
            local wx = camX + (cosA * dx - sinA * dy) * scale * invRow
            local wy = camY + (sinA * dx + cosA * dy) * scale * invRow
            local bx = (floor(wx) % bgWidth) + 1
            local by = (floor(wy) % bgHeight) + 1
            gpu.setBackground(background[by][bx])
            gpu.set(x, y, " ")
        end
        if y % 3 == 0 then os.sleep(0) end
    end

    local px0 = floor(screenWidth / 2 - playerW / 2)
    local py0 = floor(screenHeight / 2 - playerH / 2 - camZ)
    for py = 1, playerH do
        for px = 1, playerW do
            local color = playerSprite[py][px]
            gpu.setBackground(color)
            gpu.set(px0 + px, py0 + py, " ")
        end
        if py % 2 == 0 then os.sleep(0) end
    end

    gpu.setBackground(0x111133)
    gpu.set(2, 2, ("FPS: %d"):format(fps))

    local text1 = "SMFX Clone by nonogamer9"
    local text2 = "Ported to OpenComputers!"
    local centerY = floor(screenHeight / 2 + playerH / 2 + 2)
    local function centerText(y, txt)
        local x = floor((screenWidth - #txt) / 2) + 1
        gpu.set(x, y, txt)
    end
    gpu.setBackground(0x111133)
    centerText(centerY, text1)
    centerText(centerY + 1, text2)

    gpu.setActiveBuffer(0)
    gpu.bitblt(0, 1, 1, screenWidth, screenHeight, bufferIndex, 1, 1)
    os.sleep(0)

    local ev, _, _, code = event.pull(0.05, "key_down")
    if ev then
        if code == keycodes.q then break end
        if code == keycodes.w then
            playerX = playerX + cos(camAngle)
            playerY = playerY + sin(camAngle)
            camX = camX + cos(camAngle)
            camY = camY + sin(camAngle)
        end
        if code == keycodes.s then
            playerX = playerX - cos(camAngle)
            playerY = playerY - sin(camAngle)
            camX = camX - cos(camAngle)
            camY = camY - sin(camAngle)
        end
        if code == keycodes.a then
            playerX = playerX + sin(camAngle)
            playerY = playerY - cos(camAngle)
            camX = camX + sin(camAngle)
            camY = camY - cos(camAngle)
        end
        if code == keycodes.d then
            playerX = playerX - sin(camAngle)
            playerY = playerY + cos(camAngle)
            camX = camX - sin(camAngle)
            camY = camY + cos(camAngle)
        end
        if code == keycodes.space and not isJumping then
            isJumping = true
            jumpVel = 0.25
            jumpTime = 0
        end
    end

    camAngle = camAngle + 0.01

    if isJumping then
        camZ = camZ + jumpVel
        jumpVel = jumpVel - 0.025
        if camZ <= 0 then
            camZ = 0
            isJumping = false
            jumpVel = 0
        end
        os.sleep(0)
    end
    os.sleep(0)
end

gpu.setActiveBuffer(0)
gpu.freeBuffer(bufferIndex)
gpu.setBackground(0x000000)
gpu.fill(1, 1, screenWidth, screenHeight, " ")