Utility to easily create pixel perfect captures of StarfallEx chips

screengrab.lua

-- The below line is the *only* one you need to change.
--@include chopper.txt
-- The following are optional.
local OVERRIDE_WIDTH = false and 320
local OVERRIDE_HEIGHT = false and 240
local OVERRIDE_RT = false and 'out' -- Name of rendertarget to save, or none to save the screen
local OVERRIDE_DELAY = false and 2 -- How many seconds to wait until capturing
local THRESHOLD = quotaMax()*0.9
-- End configuration.

--@client
-- I only *need* to cache the ones I'm detouring, but of course, I couldn't stop there...
local _coroutine = coroutine
local _coroutine_resume = _coroutine.resume
local _coroutine_yield = _coroutine.yield
local _file = file
local _file_exists = _file.exists
local _hasPermission = hasPermission
local _hook = hook
local _hook_add = _hook.add
local _hook_remove = _hook.remove
local _hook_run = _hook.run
local _math = math
local _math_floor = _math.floor
local _math_max = _math.max
local _pairs = pairs
local _quotaAverage = quotaAverage
local _quotaTotalAverage = quotaTotalAverage
local _quotaTotalUsed = quotaTotalUsed
local _quotaUsed = quotaUsed
local _render = render
local _render_capturePixels = _render.capturePixels
local _render_clear = _render.clear
local _render_drawRect = _render.drawRect
local _render_drawText = _render.drawText
local _render_drawTexturedRectUV = _render.drawTexturedRectUV
local _render_getTextSize = _render.getTextSize
local _render_readPixel = _render.readPixel
local _render_selectRenderTarget = _render.selectRenderTarget
local _render_setBackgroundColor = _render.setBackgroundColor
local _render_setFilterMag = _render.setFilterMag
local _render_setFilterMin = _render.setFilterMin
local _render_setFont = _render.setFont
local _render_setRenderTargetTexture = _render.setRenderTargetTexture
local _render_setRGBA = _render.setRGBA
local _setupPermissionRequest = setupPermissionRequest
local _string = string
local _string_find = _string.find
local _string_sub = _string.sub
local _TEXFILTER_POINT = TEXFILTER.POINT
local _timer = timer
local _timer_create = _timer.create
local _timer_remove = _timer.remove
local _timer_simple = _timer.simple
local _timer_systime = _timer.systime

local message
local permissions = {
    'file.exists',
    'file.open',
    'render.offscreen',
    'render.screen'
}
local function init()
    for _, permission in _pairs(permissions) do
        if not _hasPermission(permission) then
            _setupPermissionRequest(permissions, "a", true)
            return
        end
    end
    _hook_remove('permissionrequest', '')
    _hook_remove('starfallused', '')
    
    message = "Waiting..."
    
    local function patch_hookname(name)
        return _string_sub(name, 1, 1) == '_' and '_'..name or name == 'render' and '_render' or name
    end
    local hooks = {}
    function _hook.add(hookname, name, func)
        hookname = patch_hookname(hookname)
        local hooks_hookname = hooks[hookname]
        if not hooks_hookname then
            hooks_hookname = {}
            hooks[hookname] = hooks_hookname
        end
        hooks_hookname[name] = true
        return _hook_add(hookname, name, func)
    end
    function _hook.remove(hookname, name)
        hookname = patch_hookname(hookname)
        local hooks_hookname = hooks[hookname]
        if hooks_hookname then
            hooks_hookname[name] = nil
        end
        return _hook_remove(patch_hookname(hookname), name)
    end
    function _hook.run(hookname, ...)
        return _hook_run(patch_hookname(hookname), ...)
    end
    
    local function patch_rt_name(name)
        return _string_sub(name, 1, 1) == '_' and '_'..name
    end
    function _render.selectRenderTarget(name)
        return _render_selectRenderTarget(name == nil and '_screengrab' or name)
    end
    
    local bg = Color(0, 0, 0, 255)
    function _render.setBackgroundColor(color)
        bg = color
    end
    
    local timers = {}
    local timers_enabled = true
    function _timer.create(name, delay, reps, func)
        timers[name] = true
        return _timer_create(name, delay, reps, func)
    end
    function _timer.remove(name)
        timers[name] = nil
        return _timer_remove(name)
    end
    function _timer.simple(delay, func)
        return _timer_simple(delay, function()
            return timers_enabled and func()
        end)
    end
    
    local i, path = 1
    repeat
        --path = 'screengrab/'..i..'.ppm.dat'
        path = 'screengrab/'..i..'.pam.dat'
        i = i+1
    until not _file_exists(path)
    local handle = assert(_file.open(path, 'wb'), "failed to open "..path)
    local w, h = OVERRIDE_WIDTH or 512, OVERRIDE_HEIGHT or 512
    --handle:write('P6 '..w..' '..h..' 255\n')
    handle:write('P7\nWIDTH '..w..'\nHEIGHT '..h..'\nDEPTH 4\nMAXVAL 255\nTUPLTYPE RGB_ALPHA\nENDHDR\n')
    local i, j = 0, w*h
    local thread = _coroutine.create(function()
        for y=0, h-1 do
            for x=0, w-1 do
                i = i+1
                local pixel = _render_readPixel(x, y)
                handle:writeByte(pixel[1])
                handle:writeByte(pixel[2])
                handle:writeByte(pixel[3])
                handle:writeByte(pixel[4]) -- PAM only
                _coroutine_yield()
            end
        end
        return true
    end)
    local duedate = OVERRIDE_DELAY and _timer_systime()+OVERRIDE_DELAY or 0
    _hook_add('render', '', function(screen)
        _render_selectRenderTarget('_screengrab')
        _render_clear(bg, false)
        
        _hook_run('_render', screen)
        if _timer_systime() < duedate then
            return
        end
        
        _hook_remove('render', '')
        _render_selectRenderTarget(OVERRIDE_RT or '_screengrab')
        _render_capturePixels()
        
        for hookname, hooks in _pairs(hooks) do
            for name in _pairs(hooks) do
                _hook_remove(hookname, name)
            end
        end
        for name in _pairs(timers) do
            _timer_remove(name)
        end
        timers_enabled = false
        
        _hook_add('renderoffscreen', '', function()
            while _math_max(_quotaUsed(), _quotaAverage(), _quotaTotalUsed(), _quotaTotalAverage()) < THRESHOLD do
                _render_selectRenderTarget(OVERRIDE_RT or '_screengrab')
                if _coroutine_resume(thread) then
                    handle:close()
                    _hook_remove('renderoffscreen', '')
                    message = "Complete"
                    return
                end
            end
            message = "Capturing... (".._math_floor(i/j*100).."%)"
        end)
    end)
    
    for path in _pairs(getScripts()) do
        if path ~= 'screengrab.txt' and path ~= 'screengrab.lua' and (_string_find(path, '%.txt$') or _string_find(path, '%.lua$')) then
            setName(path)
            dofile(path)
            return
        end
    end
    error("no include")
end
message = "Permission?"
local bg = Color(0, 0, 0, 255)
_render.createRenderTarget('_screengrab')
_hook_add('render', 'status', function()
    _render_setBackgroundColor(bg)
    _render_setRGBA(255, 255, 255, 255)
    _render_setRenderTargetTexture(OVERRIDE_RT or '_screengrab')
    --_render.drawTexturedRect(0, 0, 512, 512)
    _render_drawTexturedRectUV(0, 0, 512, 512, 0, 0, OVERRIDE_WIDTH and OVERRIDE_WIDTH/1024 or 0.5, OVERRIDE_HEIGHT and OVERRIDE_HEIGHT/1024 or 0.5)
    _render_setFont('DermaLarge')
    local w, h = _render_getTextSize(message)
    _render_setRGBA(0, 0, 0, 255)
    --_render_drawRect(8, 8, w, h)
    _render_drawText(10, 10, message)
    _render_setRGBA(255, 255, 255, 255)
    _render_drawText(8, 8, message)
end)
_hook_add('permissionrequest', '', init)
local me = player()
_hook_add('starfallused', '', function(activator, used)
    if activator == me then
        init()
    end
end)

Sample screenshots:
Helicopter demo:

CHIP-8 emulator:

rttransparency.txt demonstrating a Linux-only alpha blending bug:

Super Mario 64 intro test utilizing custom overrides: