www.pudn.com > openglbk.rar > movelight.c

/* 
 * Copyright (c) 1993-1999, 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 * Unpublished-- rights reserved under the copyright laws of the 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. 
 */ 
 
/* 
 *  movelight.c 
 *  This program demonstrates when to issue lighting and 
 *  transformation commands to render a model with a light 
 *  which is moved by a modeling transformation (rotate or 
 *  translate).  The light position is reset after the modeling 
 *  transformation is called.  The eye position does not change. 
 * 
 *  A sphere is drawn using a grey material characteristic. 
 *  A single light source illuminates the object. 
 * 
 *  Interaction:  pressing the left mouse button alters 
 *  the modeling transformation (x rotation) by 30 degrees. 
 *  The scene is then redrawn with the light in a new position. 
 */ 
#include  
#include  
 
static int spin = 0; 
 
/*  Initialize material property, light source, lighting model, 
 *  and depth buffer. 
 */ 
void init(void)  
{ 
   glClearColor (0.0, 0.0, 0.0, 0.0); 
   glShadeModel (GL_SMOOTH); 
   glEnable(GL_LIGHTING); 
   glEnable(GL_LIGHT0); 
   glEnable(GL_DEPTH_TEST); 
} 
 
/*  Here is where the light position is reset after the modeling 
 *  transformation (glRotated) is called.  This places the 
 *  light at a new position in world coordinates.  The cube 
 *  represents the position of the light. 
 */ 
void display(void) 
{ 
   GLfloat position[] = { 0.0, 0.0, 1.5, 1.0 }; 
 
   glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
   glPushMatrix (); 
   gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); 
 
   glPushMatrix (); 
   glRotated ((GLdouble) spin, 1.0, 0.0, 0.0); 
   glLightfv (GL_LIGHT0, GL_POSITION, position); 
 
   glTranslated (0.0, 0.0, 1.5); 
   glDisable (GL_LIGHTING); 
   glColor3f (0.0, 1.0, 1.0); 
   glutWireCube (0.1); 
   glEnable (GL_LIGHTING); 
   glPopMatrix (); 
 
   glutSolidTorus (0.275, 0.85, 8, 15); 
   glPopMatrix (); 
   glFlush (); 
} 
 
void reshape (int w, int h) 
{ 
   glViewport (0, 0, (GLsizei) w, (GLsizei) h); 
   glMatrixMode (GL_PROJECTION); 
   glLoadIdentity(); 
   gluPerspective(40.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0); 
   glMatrixMode(GL_MODELVIEW); 
   glLoadIdentity(); 
} 
 
void mouse(int button, int state, int x, int y) 
{ 
   switch (button) { 
      case GLUT_LEFT_BUTTON: 
         if (state == GLUT_DOWN) { 
            spin = (spin + 30) % 360; 
            glutPostRedisplay(); 
         } 
         break; 
      default: 
         break; 
   } 
} 
 
void keyboard(unsigned char key, int x, int y) 
{ 
   switch (key) { 
      case 27: 
         exit(0); 
         break; 
   } 
} 
 
int main(int argc, char** argv) 
{ 
   glutInit(&argc, argv); 
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); 
   glutInitWindowSize (500, 500);  
   glutInitWindowPosition (100, 100); 
   glutCreateWindow (argv[0]); 
   init (); 
   glutDisplayFunc(display);  
   glutReshapeFunc(reshape); 
   glutMouseFunc(mouse); 
   glutKeyboardFunc(keyboard); 
   glutMainLoop(); 
   return 0; 
}