Hi,
I have some problems using threads.
If I try to do some drawing stuff in a thread created with SDL_CreateThread,
the application exits with
Fatal signal: Segmentation Fault (SDL Parachute Deployed)
Xlib: unexpected async reply (sequence 0x66)!
If I do the same drawing within the main thread, the application runs as
expexted.
example code:
#include “SDL/SDL.h”
#include “SDL/SDL_thread.h”
#include “GL/gl.h”
bool quitThread;
int eventLoop(void * data) {
SDL_Event event;
while(!quitThread) {
SDL_WaitEvent(&event);
switch( event.type ) {
case SDL_KEYDOWN:
if (event.key.keysym.sym == SDLK_ESCAPE)
quitThread = true;
break;
case SDL_QUIT:
quitThread = true;
break;
default:
break;
}
}
return -1;
}
int repaint(void * data) {
while(!quitThread) {
glClear( GL_COLOR_BUFFER_BIT );
glLoadIdentity();
glBegin( GL_QUADS );
glVertex2i(10, 10);
glVertex2i(10, 100);
glVertex2i(100, 100);
glVertex2i(100, 10);
glEnd();
SDL_GL_SwapBuffers();
}
return -1;
}
int main( int argc, char * argv[] ) {
SDL_Init(SDL_INIT_VIDEO);
SDL_SetVideoMode( 320, 240, 32, SDL_OPENGL);
glViewport(0, 0, 320, 240);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho( 0, 320, 0, 240, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
quitThread = false;
SDL_Thread * thr1;
SDL_Thread * thr2;
thr1 = SDL_CreateThread(eventLoop, NULL);
// separate thread
// comment this line to create a working application
thr2 = SDL_CreateThread(repaint, NULL);
// no separate thread, call function directly
// uncomment this line to create a working application
//repaint(NULL);
SDL_WaitThread(thr1, NULL);
return 0;
}
Regards,
Johannes
