render in a thread

main.lua

local ffi = require("ffi")

ffi.cdef[[
int SDL_GL_MakeCurrent(void* window,void* context);
void* SDL_GL_GetCurrentContext(void);
void* SDL_GL_GetCurrentWindow(void);
]]


function love.load()
  local voidptr_size = ffi.sizeof("void*")
  local context = ffi.new("void*[1]")
  context[0] = ffi.C.SDL_GL_GetCurrentContext()
  local window = ffi.new("void*[1]")
  window[0] = ffi.C.SDL_GL_GetCurrentWindow()
  ffi.C.SDL_GL_MakeCurrent(window[0], nil)

  local channel = love.thread.getChannel("owo")
  local contextdata = love.data.newByteData(voidptr_size)
  local windowdata = love.data.newByteData(voidptr_size)
  ffi.copy(contextdata:getFFIPointer(), context, voidptr_size)
  ffi.copy(windowdata:getFFIPointer(), window, voidptr_size)
  channel:push(contextdata)
  channel:push(windowdata)

  love.thread.newThread([=[
    local ffi = require"ffi"
    ffi.cdef[[
    int SDL_GL_MakeCurrent(void* window,void* context);
    ]]
    local voidptr_size = ffi.sizeof("void*")
    local channel = love.thread.getChannel("owo")
    local context = ffi.new("void*[1]")
    local window = ffi.new("void*[1]")
    local contextdata = channel:pop()
    local windowdata = channel:pop()
    ffi.copy(context, contextdata:getFFIPointer(), voidptr_size)
    ffi.copy(window, windowdata:getFFIPointer(), voidptr_size)
    ffi.C.SDL_GL_MakeCurrent(window[0], context[0])

    require"love.graphics"
    while true do
      love.graphics.setColor(0,0,0,1)
      love.graphics.clear()
      love.graphics.setColor(1,1,1,1)
      love.graphics.print("Hello from another thread!")
      love.graphics.present()
    end
    ]=]):start()
end

function love.run()
  if love.load then love.load(love.arg.parseGameArguments(arg), arg) end
 
  -- We don't want the first frame's dt to include time taken by love.load.
  if love.timer then love.timer.step() end
 
  local dt = 0
 
  -- Main loop time.
  return function()
    -- Process events.
    if love.event then
      love.event.pump()
      for name, a,b,c,d,e,f in love.event.poll() do
        if name == "quit" then
          if not love.quit or not love.quit() then
            return a or 0
          end
        end
        love.handlers[name](a,b,c,d,e,f)
      end
    end
 
    -- Update dt, as we'll be passing it to update
    if love.timer then dt = love.timer.step() end
 
    if love.timer then love.timer.sleep(0.001) end
  end
end

function love.threaderror(_,err)
  error(err)
end