hello.c

hello.c

contents ::

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

void display(void){
  /* clear all pixels */
  glClear(GL_COLOR_BUFFER_BIT);

  /* draw white polygon (rectangle) with corners at
   * (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0)
   */
  glColor3f(0.0, 0.0, 1.0);
  glBegin(GL_POLYGON);
      glVertex3f(0.25, 0.25, 0.0);
      glVertex3f(0.75, 0.25, 0.0);
      glVertex3f(0.75, 0.75, 0.0);
      glVertex3f(0.25, 0.75, 0.0);
  glEnd();

  /* don't wait!
   * start processing buffered openGL routines
   */
  glFlush();
}

void init(void){
  /* select clearing (background) color */
  glClearColor(1.0, 0.0, 0.0, 0.0);

  /* initialise viewing values */
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}

/*
* Declare initial window size, position, and display mode
* (single buffer and RGBA). Open window with "hello"
* in its title bar. Call initialization routines.
* Register callback function to display graphics.
* Enter main loop and process events.
*/
int main(int argc, char **argv){
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutInitWindowSize(250, 250);
  glutInitWindowPosition(100, 100);
  glutCreateWindow("hello");
  init();
  glutDisplayFunc(display);
  glutMainLoop();
  return 0;
}

James Little