由于 SDL2 刚刚发布，我只是想尝试一下。在 OSX 10.8.4 上使用 xcode，我正在编译在 wiki (这里) 上找到的 SDL2+OpenGL3.2 示例。
一切顺利，除了没有窗口出现。我添加了一个在输出控制台中可见的基本跟踪（“First timer”、“Second Timer”等）。有没有想过为什么会发生这种情况？
XCode 项目：
这是main.cpp：
#include <iostream>
#include <SDL2/SDL.h>
#include <OpenGL/gl3.h>
/* A simple function that prints a message, the error code returned by SDL,
* and quits the application */
void sdldie(const char *msg)
{
std::cout << msg << SDL_GetError() << std::endl;
SDL_Quit();
exit(1);
}
void checkSDLError(int line = -1)
{
#ifndef NDEBUG
const char *error = SDL_GetError();
if (*error != '\0')
{
printf("SDL Error: %s\n", error);
if (line != -1)
printf(" + line: %i\n", line);
SDL_ClearError();
}
#endif
}
int main(int argc, char *argv[]) {
SDL_Window *mainwindow; /* Our window handle */
SDL_GLContext maincontext; /* Our opengl context handle */
if (SDL_Init(SDL_INIT_VIDEO) < 0) /* Initialize SDL's Video subsystem */
sdldie("Unable to initialize SDL"); /* Or die on error */
/* Request opengl 3.2 context.
* SDL doesn't have the ability to choose which profile at this time of writing,
* but it should default to the core profile */
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
/* Turn on double buffering with a 24bit Z buffer.
* You may need to change this to 16 or 32 for your system */
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
/* Create our window centered at 512x512 resolution */
mainwindow = SDL_CreateWindow("Test SDL2", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
512, 512, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
if (!mainwindow) /* Die if creation failed */
sdldie("Unable to create window");
checkSDLError(__LINE__);
/* Create our opengl context and attach it to our window */
maincontext = SDL_GL_CreateContext(mainwindow);
checkSDLError(__LINE__);
/* This makes our buffer swap syncronized with the monitor's vertical refresh */
SDL_GL_SetSwapInterval(1);
/* Clear our buffer with a red background */
glClearColor ( 1.0, 0.0, 0.0, 1.0 );
glClear ( GL_COLOR_BUFFER_BIT );
/* Swap our back buffer to the front */
SDL_GL_SwapWindow(mainwindow);
/* Wait 2 seconds */
std::cout << "First timer" << std::endl;
SDL_Delay(2000);
/* Same as above, but green */
glClearColor ( 0.0, 1.0, 0.0, 1.0 );
glClear ( GL_COLOR_BUFFER_BIT );
SDL_GL_SwapWindow(mainwindow);
std::cout << "Second timer" << std::endl;
SDL_Delay(2000);
/* Same as above, but blue */
glClearColor ( 0.0, 0.0, 1.0, 1.0 );
glClear ( GL_COLOR_BUFFER_BIT );
SDL_GL_SwapWindow(mainwindow);
std::cout << "Third timer" << std::endl;
SDL_Delay(2000);
/* Delete our opengl context, destroy our window, and shutdown SDL */
SDL_GL_DeleteContext(maincontext);
SDL_DestroyWindow(mainwindow);
SDL_Quit();
return 0;
}
