Using timers
LuaSDL offers support for timer objects. The problematic part is the use of timers. The LibSDL library uses callback functions to call event functions. These callbacks run in another thread and the naïve approach, where you put the Lua function in the position of callback function, would lead to Lua state corruption. There is a better way to accomplish this by using the internal LuaSDL callback function that invokes a special user event.
Timers aren't very precise and they are mostly used in GUI updates. If you need more precision, you'll need to use High Precision Event Timer (HPET), which is out of the scope of this book.
Getting ready
Each timer object uses a user-defined event that contains unique timer function identifiers represented by integer values. LuaSDL offers a slightly modified version of the SDL.SDL_AddTimer function, where it accepts two parameters instead of three. The first parameter is an interval value in milliseconds. The second is the user...
