#include <GL/glut.h>

void display()
{
  glClear(GL_COLOR_BUFFER_BIT);
  glBegin(GL_TRIANGLES);
  glColor3f(1.0, 0.0, 0.0);
  glVertex2f(-1.0, -1.0);
  glColor3f(0.0, 1.0, 0.0);
  glVertex2f(0.0, 1.0);
  glColor3f(0.0, 0.0, 1.0);
  glVertex2f(1.0, 0.0);
  glEnd();
  glFlush();
}


int main(int argc, char *argv[])
{
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutCreateWindow("C GLUT program");
  glutDisplayFunc(display);
  glutMainLoop();
  return 0;
}