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OpenGL Screencast 1 - Hello World (Glut)

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I’ve spent a good bit of time recently doing quite a bit of C and OpenGL and I figured this would be a good time to post some OpenGL screencasts. This first screencast is an introduction to OpenGL 2.1 and GLUT.

The code is available to download on Github

Download the screencast, 51.7 MB .mov

Watch the Screencast

YouTube

Resources

Great tutorials

Other libraries (than GLUT)

Code

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

/*  OpenGL with prototypes for glext */
#define GL_GLEXT_PROTOTYPES
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

/*  Globals */
double dim=2; /* dimension of orthogonal box */
char *windowName = "Hello OpenGL";

/*
 *  Display the scene
 */
void display()
{
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();

  /* draw something */
  glBegin(GL_POLYGON);
  glColor3f(1.0,0.0,0.0);
  glVertex2f(0.0,0.5);
  glColor3f(0.0,1.0,0.0);
  glVertex2f(0.5,-0.5);
  glColor3f(0.0,0.0,1.0);
  glVertex2f(-0.5,-0.5);
  glEnd();

  glFlush();
  glutSwapBuffers();
}

/*
 *  GLUT calls this routine when the window is resized
 */
void reshape(int width,int height)
{
  double w2h = (height>0) ? (double)width/height:1;
  glViewport(0,0,width,height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-dim*w2h,+dim*w2h,-dim,+dim,-dim,+dim);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

/*
 *  Start up GLUT and tell it what to do
 */
int main(int argc,char* argv[])
{
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
  glutInitWindowSize(500,500);
  glutCreateWindow(windowName);
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutMainLoop();
  return 0;
}

Questions? E-mail me: this domain AT gmail DOT com