how do I invoke threads in SDL and hwo do I pass parameters to the thread.

I did but i dont understand how to pass variables and what exactly is hapenning when you initialize a thread. Any help would be appreciated.

from the header file:

extern DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread( int (*fn)(void *), void *data);

let''s disect this...

it returns a pointer to ''SDL_Thread''. Usefull for keeping track of threads from the parent if you need to do that.

it accepts two parameters.

The first parameter is a pointer to a function. Specifically, a function returning an int, and taking a void pointer. Not void, a void pointer.

The second parameter is a void pointer as well.

Can you guess the answer?

if not...:

when you create the thread, you can pass a single pointer to it. If you need to send a good deal of information, then pack that all up into a structure or something, and then cast a pointer to that to void and pass that as the ''data'' variable in the SDL_CreateThread function call.

Then, in the called function, cast the void pointer you get back to a pointer to the structure type, which you can dereference to get to all that nifty data.

aka something like:

#include <iostream>#include <string>#include <SDL/SDL.h>using namespace std;class Something{  public:  string say;};int test( void *param ){  cout << ((Something *)param)->say << endl;  return 0;}int main( ... ){  //..SDL SETUP CODE...  Something *mysomething = new Something;  mysomething->say = "WOOT!!!";  SDL_CreateThread( test , (void*) mysomething );  //..SDL CLEANUP CODE...}

SDL threads are just there or provide thread functionality. The documentation was not intended to be general purpose tutorial on threads, but rather a tutorial on how SDL implements threads.

To learn about threads read these two tutorials:
http://www.cpp-home.com/tutorial.php?124_2 and
http://www.cpp-home.com/tutorial.php?128_1.

The first tut is general theory on threads in general. The second give a practical implementation of threads using a thread library, simliar to the SDL threads library.