#include <GL/gl.h>
#include <GL/glut.h>


/* Called when window needs to be redrawn */
void redraw()
{
    glClear(GL_COLOR_BUFFER_BIT); /* clear screen to black */
    /* just draw a boring red triangle */
    glBegin(GL_TRIANGLES);
    glColor3f(1.f, 0.f, 0.f);
    glVertex2f(-.5f, -.5f);
    glVertex2f( .5f, -.5f);
    glVertex2f( 0.f, .5f);
    glEnd();
    glFlush();
}

/* Parse arguments, and set up interface between OpenGL and window system */
main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitWindowSize(512, 512);
    glutInitDisplayMode(GLUT_RGBA);
    (void)glutCreateWindow("simple program");
    glutDisplayFunc(redraw);
    glutMainLoop();
}