我正在尝试编译这个example并稍微玩一下。我已经纠正了人们在这个例子中遇到的主要错误，他们在调用SDL_Init之前调用了sdl_gl_setattribute，但是在第一次SDL_GL_SetAttribute调用之后我仍然得到一个段错误。我之前在我的电脑上运行了带有opengl应用程序的sdl，我确信它一直在使用我的视频卡。
从这段代码中有人知道为什么会出现段错误吗？或者，此代码是否适用于任何其他人的计算机？如果它有任何区别我在ubuntu 10.04上使用freeglut3作为opengl的东西。
//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;
}
}
}
}
答案 0 :(得分：-1)
试试这个版本：
//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;
}
}
}
}