配置好SDL之后，就想在SDL中使用openGL，原以为会像在GLFW中那样简单的，实际上确花费了一整个下午不断查看文档，实例才搞定问题。
总结如下：
1）SDL对OpenGL进行了部分的封装，一些OpenGL的函数需要用SDL来实现，而不是像GLFW中那样直接用；
2）SDL的事件机制花费了一些时间来理解；
3）在处理OpenGL窗口大小变化的时候，需要先调用SDL_SetVideoMode才可以得到正确结果。
最终基本实现了一个opengl的小型框架，包括一些简单的事件处理。
代码：
/***************************************************************************** Copyright: 2012, ustc All rights reserved. contact:[email protected] File name: main.c Description:using opengl in SDL. Author:Silang Quan Version: 1.0 Date: 2012.12.01 *****************************************************************************/ #include#include #include #include #include const int SCREEN_WIDTH = 800; const int SCREEN_HEIGHT =800; const int SCREEN_BPP = 32; SDL_Surface *screen; //Whether the window is windowed or not bool windowed; //Whether the window is fine bool windowOK; void quit( int code ) { SDL_Quit( ); /* Exit program. */ exit( code ); } void toggle_fullscreen() { //If the screen is windowed if( windowed == true ) { //Set the screen to fullscreen screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL|SDL_RESIZABLE| SDL_FULLSCREEN ); //If there's an error if( screen == NULL ) { windowOK = false; return; } //Set the window state flag windowed = false; } //If the screen is fullscreen else if( windowed == false ) { //Window the screen screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL|SDL_RESIZABLE ); //If there's an error if( screen == NULL ) { windowOK = false; return; } //Set the window state flag windowed = true; } } void handleKeyEvent( SDL_keysym* keysym ) { switch( keysym->sym ) { case SDLK_ESCAPE: quit( 0 ); break; case SDLK_SPACE: break; case SDLK_F1: toggle_fullscreen(); break; default: break; } } void resizeGL(int width,int height) { if ( height == 0 ) { height = 1; } //Reset View glViewport( 0, 0, (GLint)width, (GLint)height ); //Choose the Matrix mode glMatrixMode( GL_PROJECTION ); //reset projection glLoadIdentity(); //set perspection gluPerspective( 45.0, (GLfloat)width/(GLfloat)height, 0.1, 100.0 ); //choose Matrix mode glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); } void handleEvents() { // Our SDL event placeholder. SDL_Event event; //Grab all the events off the queue. while( SDL_PollEvent( &event ) ) { switch( event.type ) { case SDL_KEYDOWN: // Handle key Event handleKeyEvent( &event.key.keysym ); break; case SDL_QUIT: // Handle quit requests (like Ctrl-c). quit( 0 ); break; case SDL_VIDEORESIZE: //Handle resize event screen = SDL_SetVideoMode(event.resize.w, event.resize.h, 16, SDL_OPENGL|SDL_RESIZABLE); if ( screen ) { resizeGL(screen->w, screen->h); } break; } } } void initSDL(int width,int height,int bpp,int flags) { // First, initialize SDL's video subsystem. if( SDL_Init( SDL_INIT_VIDEO ) < 0 ) { fprintf( stderr, "Video initialization failed: %s\n", SDL_GetError( ) ); quit( 1 ); } atexit(SDL_Quit); //Set some Attribute of OpenGL in SDL SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 ); SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); //Set the video mode screen= SDL_SetVideoMode( width, height, bpp,flags); if(!screen ) { fprintf( stderr, "Video mode set failed: %s\n",SDL_GetError( ) ); quit( 1 ); windowed=false; } else windowed=true; resizeGL(screen->w, screen->h); //Set caption SDL_WM_SetCaption( "OpenGL Test", NULL ); } void renderGL() { // Clear the color and depth buffers. glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); // We don't want to modify the projection matrix. */ glMatrixMode( GL_MODELVIEW ); glLoadIdentity( ); // Move down the z-axis. glTranslatef( 0.0, 0.0, -5.0 ); //Draw a square glBegin(GL_QUADS); glColor3f(1.0f,0.0f,0.0f); glVertex3f(-1.0f , -1.0f , 1.0f ); glColor3f(0.0f,1.0f,0.0f); glVertex3f( 1.0f , -1.0f , 1.0f ); glColor3f(0.0f,0.0f,1.0f); glVertex3f( 1.0f , 1.0f , 1.0f ); glColor3f(1.0f,1.0f,0.0f); glVertex3f(-1.0f , 1.0f , 1.0f ); glEnd(); SDL_GL_SwapBuffers( ); } void initGL( int width, int height ) { float ratio = (float) width / (float) height; // Our shading model--Gouraud (smooth). glShadeModel( GL_SMOOTH ); // Set the clear color. glClearColor( 0, 0, 0, 0 ); // Setup our viewport. glViewport( 0, 0, width, height ); //Change to the projection matrix and set our viewing volume. glMatrixMode( GL_PROJECTION ); glLoadIdentity(); gluPerspective( 60.0, ratio, 1.0, 100.0 ); } int main( int argc, char* argv[] ) { // Color depth in bits of our window. int flags= SDL_OPENGL|SDL_RESIZABLE; //Set the SDL initSDL(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,flags); //Set the OpenGL initGL(SCREEN_WIDTH, SCREEN_HEIGHT ); //main loop while(true) { /* Process incoming events. */ handleEvents( ); /* Draw the screen. */ renderGL( ); } return 0; }
编译命令：
g++ main.c -o mian -lSDL -lglut -lGLU
#in opensuse g++ main.c -o main -lSDL -lGL -lGLU
SDLOpenGLFramework
这里给一个C++写的OpenGL编程框架。
https://github.com/SilangQuan/SDLOpenGLFramework
SDL英文教程-http://lazyfoo.net/