How Does OpenGL's Coordinate System Work?
#include <iostream>
#include <stdlib.h>
#include <GLUT/GLUT.h>

void RenderScene()
{
    glLoadIdentity ();
    glClear(GL_COLOR_BUFFER_BIT);

    glBegin( GL_POINTS );

        glVertex3f( 0, 0, 0 );

    glEnd();


    glFlush();
}

int main(int argc, char **argv)
{
    glutInit( &argc, argv );
    glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB );
    glutInitWindowSize( 600, 600 );
    glutCreateWindow( "OpenGL" );
    glutDisplayFunc( RenderScene );
    glutMainLoop();
    return 0;
}