OpenGL

glClear( GL_COLOR_BUFFER_BIT ); /* clear the screen */
glMatrixMode( GL_PROJECTION );  /* Seting up the scene projection*/    
glLoadIdentity();                    
glFrustum(-1, 1, -1, 1, 1, 100); 
 
glMatrixMode( GL_MODELVIEW ); /* clear the current model matrix */
glLoadIdentity();                  
glTranslatef( 0, 0, -3 ); /* moves the object 3 units on the z-axis*/          
 
/* Draws a polygon with 4 vertices and color blue*/
glBegin( GL_POLYGON );              
glColor3f( 0, 0, 1 );               
glVertex3f( -1, -1, 0 );            
glVertex3f( -1, 1, 0 );            
glVertex3f( 1, 1, 0 );              
glVertex3f( 1, -1, 0 );             
glEnd();