I wrote a short OpenGL/SDL program (this is the first time I've done so). The program is based off the one in the OpenGL Red Book but, nothing is on screen when I run it.

Here's the code:

#include <stdio.h>
#include <SDL/SDL.h>
#include <GL/gl.h>
#include <GL/glu.h>

SDL_Surface *screen;

SDL_Event event;

int main(void)
{

 SDL_Init(SDL_INIT_VIDEO); //Initilization

 SDL_WM_SetCaption("\"Hello, World!\"", "\"Hello, World!\""); //The window caption is "Hello, World!"

 SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 );     //-+
 SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 );   // |
 SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 );    // |-Window attributes
 SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );  // |
 SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); //-+

 screen = SDL_SetVideoMode(640, 480, 16, SDL_OPENGL); //Create a window

 //Drawing
  //Setup

   glClearColor(0.0, 0.0, 0.0, 0.0);
   glClear(GL_COLOR_BUFFER_BIT);
   glColor3f(1.0, 1.0, 1.0);
   glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();

  //Polygon

   glBegin(GL_POLYGON);
    glVertex2f(0.0, 0.0);
    glVertex2f(0.0, 240.0);
    glVertex2f(320.0, 240.0);
    glVertex2f(320.0, 0.0);
   glEnd();
   glFlush();

 while(1)
 {
  glFlush();
  SDL_Flip(screen); //Update the screen

 }

 return 0;
}