/*
 * Simple OpenGL test: the famous triangle.
 *
 * Compile as:
 *
 * gcc simple-opengl-test.c -o simple-opengl-test -Wall -ggdb -O0 -pthread -lm -lglut `pkg-config --cflags gl glu` `pkg-config --libs gl glu`
 *
 * Author: Alejandro Piñeiro Iglesias <apinheiro@igalia.com>
 *
 */

#include <stdio.h>

#define GL_GLEXT_PROTOTYPES

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

int width;
int height;
int window;
int fullscreen;

void
on_key_press (unsigned char key,
              int x, int y)
{
  glutDestroyWindow (window);
  exit (0);
}

void
scene_render (void)
{
  glBegin(GL_TRIANGLES);
  glColor3f(1.0f,0.0f,0.0f);
  glVertex3f(0, 0, -5);
  glColor3f(0.0f,1.0f,0.0f);
  glVertex3f(width, 0, -5);
  glColor3f(0.0f,0.0f,1.0f);
  glVertex3f(width/2, height, -5);
  glEnd();

  glutSwapBuffers();

  glutPostRedisplay();
}

static void
setup ()
{
  glClearColor (0.0, 0.0, 0.0, 1.0);
  glClear (GL_COLOR_BUFFER_BIT);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  glViewport (0, 0, width, height);
  glOrtho (0, width, 0, height, -100, 100);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

int
main(int argc,
     char *argv[])
{
  if (argc < 4) {
    printf ("Usage: ./simple-opengl-test width height full-screen\n");
    exit (0);
  }

  width = atoi (argv[1]);
  height = atoi (argv[2]);
  fullscreen = atoi (argv[3]);

  glutInit (&argc, argv);
  glutInitDisplayMode (GLUT_RGBA | GLUT_DOUBLE);
  glutInitWindowSize (width, height);
  window = glutCreateWindow (argv[0]);

  setup();

  glutDisplayFunc (scene_render);
  glutKeyboardFunc (on_key_press);

  printf ("GL_VERSION = %s\n", (char *) glGetString (GL_VERSION));

  if (fullscreen)
    glutFullScreen();
  glutMainLoop();

  return 0;
}