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Nanook

OpenGL basic gluLookAt questions..

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Nanook    537
The source below is just a sample code that I got to play around with.. the gluLookAt function is put in the reshape function.. but is the reshape function loaded when the program runs aswell? what if I want to have a button that changes the view by calling gluLookAt, wouldnt this view be changed if I resized the window?
/*
 * Copyright (c) 1993-1997, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED
 * Permission to use, copy, modify, and distribute this software for
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation, and that
 * the name of Silicon Graphics, Inc. not be used in advertising
 * or publicity pertaining to distribution of the software without specific,
 * written prior permission.
 *
 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
 * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * US Government Users Restricted Rights
 * Use, duplication, or disclosure by the Government is subject to
 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
 * clause at DFARS 252.227-7013 and/or in similar or successor
 * clauses in the FAR or the DOD or NASA FAR Supplement.
 * Unpublished-- rights reserved under the copyright laws of the
 * United States.  Contractor/manufacturer is Silicon Graphics,
 * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
 *
 * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
 */

/*
 *  planet.c
 *  This program shows how to composite modeling transformations
 *  to draw translated and rotated models.
 *  Interaction:  pressing the d D and y Y keys (day and year)
 *  alters the rotation of the planet around the sun.
 *  ESC key exits
 *
 *  modified smr may 03 - animate with stop s and Start S
 *  modified smr april 08 to test for single buffer and translates
 */
#include <stdio.h>
#include <GL/glut.h>
#include <stdlib.h>

static int year = 0, day = 0;

void init(void)
{
   glClearColor (0.0, 0.0, 0.0, 0.0);

   glEnable(GL_DEPTH_TEST); // comment this out and see what happens.

}

void animate(void){
  day = (day + 5) % 360;
  year = (year + 1) % 360;
  glutPostRedisplay();
}

void display(void)
{
   glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   glPushMatrix();
	glColor3f (1.0, 1.0, 1.0);
	glutSolidSphere(1.0, 20, 16);   /* draw sun */

	glRotatef ((GLfloat) year, 0.0, 1.0, 0.0);
	glTranslatef (-2.0, 0.0, 0.0); // try -2 on the x and note starting point of planet
	glRotatef ((GLfloat) day, 0.0, 1.0, 0.0);

	glColor3f (1.0, 1.0, 0.0);
	glutWireSphere(0.2, 10, 8);    /* draw smaller planet */
   glPopMatrix();

   glutSwapBuffers();
   glFlush();
}

void reshape (int w, int h)
{
   glViewport (0, 0, (GLsizei) w, (GLsizei) h);

   glMatrixMode (GL_PROJECTION);
   glLoadIdentity ();
   gluPerspective(60.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);

   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
   //glTranslatef (0.0, 0.0, -3.0); // try the lookat or this. try values of 1.0 as well
}

void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 'd':
         day = (day + 10) % 360;
         glutPostRedisplay();
         break;
      case 'D':
         day = (day - 10) % 360;
         glutPostRedisplay();
         break;
      case 'y':
         year = (year + 5) % 360;
         glutPostRedisplay();
         break;
      case 'Y':
         year = (year - 5) % 360;
         glutPostRedisplay();
         break;
      case 's':
      	glutIdleFunc(NULL);
         break;
      case 'S':
      	glutIdleFunc(animate);
         break;
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
   //glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize (500, 500);
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0;
}


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