/* Example of OpenGL rendering through SDL. */#include <SDL/SDL.h>#include <GL/gl.h>#include <stdio.h>#include <stdlib.h>int main(){    /* Initialize SDL as usual. */    if (SDL_Init(SDL_INIT_VIDEO) != 0) {	printf("Error: %s\n", SDL_GetError());	return 1;    }    atexit(SDL_Quit);    /* Enable OpenGL double buffering. */    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);    /* Set the color depth (16-bit 565). */    SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5);    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 6);    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5);    /* Create a 640x480, 16 bit window with support for       OpenGL rendering. Unfortunately we won't know       whether this is hardware accelerated. */    if (SDL_SetVideoMode(640, 480, 16, SDL_OPENGL) == NULL) {	printf("Error: %s\n", SDL_GetError());	return 1;    }    /* Set a window title. */    SDL_WM_SetCaption("OpenGL with SDL!", "OpenGL");    /* We can now use any OpenGL rendering commands. */    glViewport(80, 0, 480, 480);    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    glFrustum(-1.0, 1.0, -1.0, 1.0, 1.0, 100.0);    glClearColor(0, 0, 0, 0);    glMatrixMode(GL_MODELVIEW);    glLoadIdentity();    glClear(GL_COLOR_BUFFER_BIT);    glBegin(GL_TRIANGLES);    glColor3f(1.0, 0, 0);    glVertex3f(0.0, 1.0, -2.0);    glColor3f(0, 1.0, 0);    glVertex3f(1.0, -1.0, -2.0);    glColor3f(0, 0, 1.0);    glVertex3f(-1.0, -1.0, -2.0);    glEnd();    glFlush();    /* Display the back buffer to the screen. */    SDL_GL_SwapBuffers();    /* Wait a few seconds. */    SDL_Delay(5000);    return 0;}