sdl app segfaults sur sdl_gl_setattribute

Question

Je suis en train de compiler ce example et de jouer avec un peu. J'ai déjà corrigé l'erreur principale que les gens avaient avec cet exemple où ils appellent sdl_gl_setattribute avant que SDL_Init soit appelé, mais je reçois toujours un segfault juste après le premier appel SDL_GL_SetAttribute. J'ai déjà utilisé sdl avec des applications opengl sur mon ordinateur et je suis certain que cela fonctionne avec ma carte vidéo.

De ce code quelqu'un sait-il pourquoi il segmenterait? Ou, ce code fonctionne-t-il sur l'ordinateur de quelqu'un d'autre? Si cela fait une différence, je suis sur ubuntu 10.04 en utilisant freeglut3 pour opengl stuff.

//compile with cc triangle.c -o triangle `sdl-config --libs --cflags` -lglut 

#include <stdio.h> 
#include "SDL.h" 
#include <GL/gl.h> 

int event_thread(void* nothing); 

int main(int argc, char** argv) { 
    float theta = 0.0f; 

    SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTTHREAD); 

    //first set buffer stuff, then doublebuf (if wanted), then SDL_SetVideoMode() 
    if(SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1) < 0) { printf("couldn't set double buffering: %s\n", SDL_GetError()); } 

    //go through and get the values to see if everything was set 
    int red, green, blue, doublebuf; 
    SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &red); 
    SDL_GL_GetAttribute(SDL_GL_GREEN_SIZE, &green); 
    SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &blue); 
    SDL_GL_GetAttribute(SDL_GL_DOUBLEBUFFER, &doublebuf); 
    printf("red size, green size, blue size: <%d, %d, %d>\ndouble buffered? %s\n", red, green, blue, (doublebuf == 1 ? "yes" : "no")); 

    //pass sdl_resizable if it's an opengl application that is windowed and not fullscreened 
    SDL_Surface* screen = SDL_SetVideoMode(600, 300, 32, SDL_OPENGL | SDL_HWSURFACE | SDL_NOFRAME | SDL_RESIZABLE); 
    if(screen == NULL) { 
     printf("video error: %s\n", SDL_GetError()); 
    } 

    //print video card memory 
    const SDL_VideoInfo* info = SDL_GetVideoInfo(); 
    printf("video card memory (in megabytes): %d\n", info->video_mem); 

    //set opengl params for drawing in 3d space 
    glViewport(0, 0, 600, 300); 
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f); 
    glClearDepth(1.0); 
    glDepthFunc(GL_LESS); 
    glEnable(GL_DEPTH_TEST); 
    glShadeModel(GL_SMOOTH); 
    glMatrixMode(GL_PROJECTION); 
    glMatrixMode(GL_MODELVIEW); 

    //start up the event thread 
    int done = 0; 
    SDL_Thread* evt_thrd; 
    evt_thrd = SDL_CreateThread(event_thread, (void*)&done); 

    for(;!done;) { 
     //clear and move to 0, 0, 0 
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
     glTranslatef(0.0f, 0.0f, 0.0f); 
     glRotatef(theta, 0.0f, 0.0f, 1.0f); 

     //draw the triangle 
     glBegin(GL_TRIANGLES); 
     glColor3f(1.0f, 0.0f, 0.0f); 
     glVertex2f(0.0f, 1.0f); 
     glColor3f(0.0f, 1.0f, 0.0f); 
     glVertex2f(0.87f, -0.5f); 
     glColor3f(0.0f, 0.0f, 1.0f); 
     glVertex2f(-0.87f, -0.5f); 
     glEnd(); 

     theta += 0.5f; 
     SDL_GL_SwapBuffers(); 
    } 

    SDL_Quit(); 
    return 0; 
} 

int event_thread(void* nothing) { 
    int* done = (int*)nothing; 
    SDL_Event event; 

    while(1) { 
     while(SDL_PollEvent(&event)) { 
      if(event.type == SDL_QUIT || 
      (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_ESCAPE)) { 
       *done = 1; 
       return 0; 
      } 
     } 
    } 
} 

Answer 1

Essayez cette version:

//compile with cc triangle.c -o triangle `sdl-config --libs --cflags` -lglut 

#include <stdio.h> 
#include "SDL.h" 
#include "SDL_opengl.h" 

int event_thread(void* nothing); 

int main(int argc, char** argv) { 
    float theta = 0.0f; 

    SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTTHREAD); 

    //first set buffer stuff, then doublebuf (if wanted), then SDL_SetVideoMode() 
    if(SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32) < 0) { printf("opengl error: %s\n", SDL_GetError()); } 
    if(SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1) < 0) { printf("couldn't set double buffering: %s\n", SDL_GetError()); } 

    //pass sdl_resizable if it's an opengl application that is windowed and not fullscreened 
    SDL_Surface* screen = SDL_SetVideoMode(600, 300, 32, SDL_OPENGL | SDL_HWSURFACE | SDL_NOFRAME | SDL_RESIZABLE); 
    if(screen == NULL) { 
     printf("video error: %s\n", SDL_GetError()); 
    } 

    //go through and get the values to see if everything was set 
    int red, green, blue, doublebuf; 
    SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &red); 
    SDL_GL_GetAttribute(SDL_GL_GREEN_SIZE, &green); 
    SDL_GL_GetAttribute(SDL_GL_RED_SIZE, &blue); 
    SDL_GL_GetAttribute(SDL_GL_DOUBLEBUFFER, &doublebuf); 
    printf("red size, green size, blue size: <%d, %d, %d>\ndouble buffered? %s\n", red, green, blue, (doublebuf == 1 ? "yes" : "no")); 

    //print video card memory 
    const SDL_VideoInfo* info = SDL_GetVideoInfo(); 
    printf("video card memory (in megabytes): %d\n", info->video_mem); 

    //set opengl params for drawing in 3d space 
    glViewport(0, 0, 600, 300); 
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f); 
    glClearDepth(1.0); 
    glDepthFunc(GL_LESS); 
    glEnable(GL_DEPTH_TEST); 
    glShadeModel(GL_SMOOTH); 
    glMatrixMode(GL_PROJECTION); 
    glMatrixMode(GL_MODELVIEW); 

    //start up the event thread 
    int done = 0; 
    SDL_Thread* evt_thrd; 
    evt_thrd = SDL_CreateThread(event_thread, (void*)&done); 

    for(;!done;) { 
     //clear and move to 0, 0, 0 
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
     glTranslatef(0.0f, 0.0f, 0.0f); 
     glRotatef(theta, 0.0f, 0.0f, 1.0f); 

     //draw the triangle 
     glBegin(GL_TRIANGLES); 
     glColor3f(1.0f, 0.0f, 0.0f); 
     glVertex2f(0.0f, 1.0f); 
     glColor3f(0.0f, 1.0f, 0.0f); 
     glVertex2f(0.87f, -0.5f); 
     glColor3f(0.0f, 0.0f, 1.0f); 
     glVertex2f(-0.87f, -0.5f); 
     glEnd(); 

     theta += 0.5f; 
     SDL_GL_SwapBuffers(); 
    } 

    SDL_Quit(); 
    return 0; 
} 

int event_thread(void* nothing) { 
    int* done = (int*)nothing; 
    SDL_Event event; 

    while(1) { 
     while(SDL_PollEvent(&event)) { 
      if(event.type == SDL_QUIT || 
      (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_ESCAPE)) { 
       *done = 1; 
       return 0; 
      } 
     } 
    } 
}