www.pudn.com > openglbk.rar > stencil.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 * Unpublished-- rights reserved under the copyright laws of the 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. 
 */ 
 
/* 
 *  stencil.c 
 *  This program demonstrates use of the stencil buffer for 
 *  masking nonrectangular regions.   
 *  Whenever the window is redrawn, a value of 1 is drawn  
 *  into a diamond-shaped region in the stencil buffer.   
 *  Elsewhere in the stencil buffer, the value is 0. 
 *  Then a blue sphere is drawn where the stencil value is 1, 
 *  and yellow torii are drawn where the stencil value is not 1. 
 */ 
#include  
#include  
 
#define YELLOWMAT   1 
#define BLUEMAT 2 
 
void init (void)  
{ 
   GLfloat yellow_diffuse[] = { 0.7, 0.7, 0.0, 1.0 }; 
   GLfloat yellow_specular[] = { 1.0, 1.0, 1.0, 1.0 }; 
 
   GLfloat blue_diffuse[] = { 0.1, 0.1, 0.7, 1.0 }; 
   GLfloat blue_specular[] = { 0.1, 1.0, 1.0, 1.0 }; 
 
   GLfloat position_one[] = { 1.0, 1.0, 1.0, 0.0 }; 
 
   glNewList(YELLOWMAT, GL_COMPILE); 
   glMaterialfv(GL_FRONT, GL_DIFFUSE, yellow_diffuse); 
   glMaterialfv(GL_FRONT, GL_SPECULAR, yellow_specular); 
   glMaterialf(GL_FRONT, GL_SHININESS, 64.0); 
   glEndList(); 
 
   glNewList(BLUEMAT, GL_COMPILE); 
   glMaterialfv(GL_FRONT, GL_DIFFUSE, blue_diffuse); 
   glMaterialfv(GL_FRONT, GL_SPECULAR, blue_specular); 
   glMaterialf(GL_FRONT, GL_SHININESS, 45.0); 
   glEndList(); 
 
   glLightfv(GL_LIGHT0, GL_POSITION, position_one); 
 
   glEnable(GL_LIGHT0); 
   glEnable(GL_LIGHTING); 
   glEnable(GL_DEPTH_TEST); 
 
   glClearStencil(0x0); 
   glEnable(GL_STENCIL_TEST); 
} 
 
/* Draw a sphere in a diamond-shaped section in the 
 * middle of a window with 2 torii. 
 */ 
void display(void) 
{ 
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
 
/* draw blue sphere where the stencil is 1 */ 
   glStencilFunc (GL_EQUAL, 0x1, 0x1); 
   glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP); 
   glCallList (BLUEMAT); 
   glutSolidSphere (0.5, 15, 15); 
 
/* draw the tori where the stencil is not 1 */ 
   glStencilFunc (GL_NOTEQUAL, 0x1, 0x1); 
   glPushMatrix(); 
      glRotatef (45.0, 0.0, 0.0, 1.0); 
      glRotatef (45.0, 0.0, 1.0, 0.0); 
      glCallList (YELLOWMAT); 
      glutSolidTorus (0.275, 0.85, 15, 15); 
      glPushMatrix(); 
         glRotatef (90.0, 1.0, 0.0, 0.0); 
         glutSolidTorus (0.275, 0.85, 15, 15); 
      glPopMatrix(); 
   glPopMatrix(); 
} 
 
/*  Whenever the window is reshaped, redefine the  
 *  coordinate system and redraw the stencil area. 
 */ 
void reshape(int w, int h) 
{ 
   glViewport(0, 0, (GLsizei) w, (GLsizei) h); 
 
/* create a diamond shaped stencil area */ 
   glMatrixMode(GL_PROJECTION); 
   glLoadIdentity(); 
   if (w <= h) 
      gluOrtho2D(-3.0, 3.0, -3.0*(GLfloat)h/(GLfloat)w, 
                 3.0*(GLfloat)h/(GLfloat)w); 
   else 
      gluOrtho2D(-3.0*(GLfloat)w/(GLfloat)h, 
                 3.0*(GLfloat)w/(GLfloat)h, -3.0, 3.0); 
   glMatrixMode(GL_MODELVIEW); 
   glLoadIdentity(); 
 
   glClear(GL_STENCIL_BUFFER_BIT); 
   glStencilFunc (GL_ALWAYS, 0x1, 0x1); 
   glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE); 
   glBegin(GL_QUADS); 
      glVertex2f (-1.0, 0.0); 
      glVertex2f (0.0, 1.0); 
      glVertex2f (1.0, 0.0); 
      glVertex2f (0.0, -1.0); 
   glEnd(); 
 
   glMatrixMode(GL_PROJECTION); 
   glLoadIdentity(); 
   gluPerspective(45.0, (GLfloat) w/(GLfloat) h, 3.0, 7.0); 
   glMatrixMode(GL_MODELVIEW); 
   glLoadIdentity(); 
   glTranslatef(0.0, 0.0, -5.0); 
} 
 
void keyboard(unsigned char key, int x, int y) 
{ 
   switch (key) { 
      case 27: 
         exit(0); 
         break; 
   } 
} 
 
/* Main Loop 
 * Be certain to request stencil bits. 
 */ 
int main(int argc, char** argv) 
{ 
   glutInit(&argc, argv); 
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB  
                        | GLUT_DEPTH | GLUT_STENCIL); 
   glutInitWindowSize (400, 400); 
   glutInitWindowPosition (100, 100); 
   glutCreateWindow (argv[0]); 
   init (); 
   glutReshapeFunc(reshape); 
   glutDisplayFunc(display); 
   glutKeyboardFunc(keyboard); 
   glutMainLoop(); 
   return 0; 
}