main.cpp

#include <iostream>
#include <SDL.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <cstdlib>

void drawTriangle();
void drawCube();
int main()
{
  if(SDL_Init(SDL_INIT_VIDEO))
  {
    std::cerr<<"error init SDL\n";
    exit(EXIT_FAILURE);
  }


  SDL_Rect screenSize;
  SDL_GetDisplayBounds(0,&screenSize);

  SDL_Window *window = SDL_CreateWindow(
        "OpenGL Demo",
        SDL_WINDOWPOS_CENTERED,
        SDL_WINDOWPOS_CENTERED,
        screenSize.w/2,
        screenSize.h/2,
        SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE

        );

  SDL_GLContext glContext;
  // set OpenGL attributes
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION,2);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION,0);
  SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE,16);
  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1);
  glContext=SDL_GL_CreateContext(window);
  // now make this the active context
  SDL_GL_MakeCurrent(window,glContext);
  glClearColor(1.0,1.0,1.0,1.0);
  glClear(GL_COLOR_BUFFER_BIT);
  glMatrixMode(GL_PROJECTION);
  gluPerspective(45.0f,(float)screenSize.w/screenSize.h,
                 0.5,100
                 );

  glMatrixMode(GL_MODELVIEW);
  gluLookAt(2,2,2,0,0,0,0,1,0);
  glEnable(GL_DEPTH_TEST);
  bool quit=false;
  SDL_Event event;
  while(!quit)
  {
    while(SDL_PollEvent(&event))
    {
      switch( event.type)
      {
        case SDL_QUIT : quit =true; break;
        case SDL_KEYDOWN :
          switch(event.key.keysym.sym)
          {
            case SDLK_ESCAPE : quit= true; break;
            case SDLK_w : glPolygonMode(GL_FRONT_AND_BACK,GL_LINE); break;
            case SDLK_s : glPolygonMode(GL_FRONT_AND_BACK,GL_FILL); break;
          }

        break;
      }

    }

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    //drawTriangle();
    drawCube();
    SDL_GL_SwapWindow(window);
  } // end quit loop
}

void drawTriangle()
{
  static int rot=0;
  glPushMatrix();
    glRotated(++rot,0,1,0);
    glBegin(GL_TRIANGLES);
      glColor3f(1.0f,0.0,0.0f);
      glVertex3f(0.0f,1.0f,0.0f);
      glColor3f(0.0f,1.0f,0.0f);
      glVertex3f(1.0f,-1.0f,0.0f);
      glColor3f(0.0f,0.0f,1.0f);
      glVertex3f(-1.0f,-1.0f,0.0f);
    glEnd();
  glPopMatrix();
}

void drawCube()
{
  static int rot=0;
  glPushMatrix();
    glRotated(++rot,0,1,0);
    glBegin(GL_QUADS);
      glColor3f(1.0,0.0,0.0);
      glVertex3f(-1,-1,1);
      glVertex3f(-1,1,1);
      glVertex3f(1,1,1);
      glVertex3f(1,-1,1);
    glEnd();
  glPopMatrix();

}