我之前使用过SDL和glut，没有遇到太多问题，现在我想在一个项目中使用SDL/opengl。但是，当我调用第一个openGl函数时，无论我尝试哪个openGl函数，都会出现段错误。
我尝试了网上找到的5个不同的示例程序。我尝试了来自sdl网站的this SDLgears示例，只对源代码进行了很小的更改（从SDL_GetKeyState--> SDL_GetKeyboardState），但也失败了。这让我认为我的库可能有问题。
以下是我相关的macports库:
程序输出：
我尝试了网上找到的5个不同的示例程序。我尝试了来自sdl网站的this SDLgears示例，只对源代码进行了很小的更改（从SDL_GetKeyState--> SDL_GetKeyboardState），但也失败了。这让我认为我的库可能有问题。
以下是我相关的macports库:
libsdl-devel @1.3.0-5552_0 (active)
libsdl_mixer @1.2.11_3 (active)
mesa @7.8.2_2 (active)
虽然我不确定-lGL是Mesa还是系统库。
我尝试的所有示例基本上都可以归结为以下内容：
#include <SDL/SDL.h>
#include <SDL/SDL_opengl.h>
void
warn_if_fail(int sdl_ret)
{
if (sdl_ret < 0)
printf("opengl error: %s\n", SDL_GetError());
}
int main(int argc __attribute__((unused)), char* args[] __attribute__((unused)))
{
// init sdl video
SDL_Init(SDL_INIT_VIDEO);
//print video info
const SDL_VideoInfo* info = SDL_GetVideoInfo();
printf("video card memory: %d\n", info->video_mem);
printf("current_w: %d, current_hh: %d\n", info->current_w, info->current_h);
printf("bpp: %d\n", info->vfmt->BitsPerPixel);
printf("hardware_available: %d\n", info->hw_available);
printf("blit_hw: %d\n", info->blit_hw );
// set SDL_GL attributes
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8) );
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8) );
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8) );
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8) );
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32) );
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1) );
warn_if_fail( SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 32) );
// set video mode
SDL_Surface* screen;
if ( (screen = SDL_SetVideoMode( 640, 480, 32, SDL_OPENGL) ) == NULL)
printf("video error: %s\n", SDL_GetError());
printf("\nSDL_SetVideoMode success!\n");
// print some attributes to make sure they were set correctly
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>\n", red, green, blue);
printf("double buffered? %s\n\n", doublebuf == 1 ? "yes" : "no");
// init openGl stuff
printf("about to segfault\n");
glViewport(0,0,640,480);
printf("won't reach this message\n");
// this also would have segfaulted
// All openGl functions I've tried have segfaulted
glClearColor(0, 0, 0, 0);
SDL_Quit();
return 0;
}
Makefile：
PROJ = sdl_opengl_test
CXX=g++
Q = @
CPP_SRC = sdl_opengl_test.cpp
OBJ = $(CPP_SRC:.cpp=.o)
WARNINGFLAGS = -Wall -Wextra -Wshadow -Werror
INCLUDES = -I/opt/local/include
CPPFLAGS = $(WARNINGFLAGS) $(INCLUDES) -D_THREAD_SAFE
LDFLAGS = -L/opt/local/lib -lSDL -lGL -lGLU
$(PROJ): $(OBJ)
@echo LD $@
$(Q)$(CXX) $(OBJ) $(LDFLAGS) -o $@
%.o : %.cpp
@echo CXX $@
$(Q)$(CXX) $(CPPFLAGS) -c $< -o $@
clean:
rm -f $(PROJ)
rm -f $(OBJ)
程序输出：
greg@pimptop ~/space/blaah (git)-[master] % ./sdl_opengl_test
video card memory: 0
current_w: 1680, current_hh: 1050
bpp: 32
hardware_available: 0
blit_hw: 0
SDL_SetVideoMode success!
red size, green size, blue size: <8, 8, 8>
double buffered? yes
about to segfault
[1] 37420 segmentation fault ./sdl_opengl_test
(gdb) run
Starting program: /Users/greg/space/blaah/sdl_opengl_test
Reading symbols for shared libraries .++++++............................. done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
video card memory: 0
current_w: 1680, current_hh: 1050
bpp: 32
hardware_available: 0
blit_hw: 0
Reading symbols for shared libraries . done
Reading symbols for shared libraries .. done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
SDL_SetVideoMode success!
red size, green size, blue size: <8, 8, 8>
double buffered? yes
about to segfault
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000000
0x0000000000000000 in ?? ()
(gdb) bt
#0 0x0000000000000000 in ?? ()
#1 0x0000000100000d55 in main (argc=1, args=0x7fff5fbff378) at sdl_opengl_test.cpp:50
谢谢