progs/redbook/stencil.c

   1
   2 /* Copyright (c) Mark J. Kilgard, 1994. */
   3
   4 /*
   5  * (c) Copyright 1993, Silicon Graphics, Inc.
   6  * ALL RIGHTS RESERVED
   7  * Permission to use, copy, modify, and distribute this software for
   8  * any purpose and without fee is hereby granted, provided that the above
   9  * copyright notice appear in all copies and that both the copyright notice
  10  * and this permission notice appear in supporting documentation, and that
  11  * the name of Silicon Graphics, Inc. not be used in advertising
  12  * or publicity pertaining to distribution of the software without specific,
  13  * written prior permission.
  14  *
  15  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
  16  * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  18  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  19  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  20  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
  21  * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
  22  * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
  23  * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
  24  * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
  25  * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
  26  * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
  27  *
  28  * US Government Users Restricted Rights
  29  * Use, duplication, or disclosure by the Government is subject to
  30  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  31  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  32  * clause at DFARS 252.227-7013 and/or in similar or successor
  33  * clauses in the FAR or the DOD or NASA FAR Supplement.
  34  * Unpublished-- rights reserved under the copyright laws of the
  35  * United States.  Contractor/manufacturer is Silicon Graphics,
  36  * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
  37  *
  38  * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
  39  */
  40 /*  stencil.c
  41  *  This program draws two rotated tori in a window.
  42  *  A diamond in the center of the window masks out part
  43  *  of the scene.  Within this mask, a different model
  44  *  (a sphere) is drawn in a different color.
  45  */
  46 #include <stdlib.h>
  47 #include <GL/glut.h>
  48
  49 #define YELLOWMAT   1
  50 #define BLUEMAT 2
  51
  52 void myinit (void)
  53 {
  54     GLfloat yellow_diffuse[] = { 0.7, 0.7, 0.0, 1.0 };
  55     GLfloat yellow_specular[] = { 1.0, 1.0, 1.0, 1.0 };
  56
  57     GLfloat blue_diffuse[] = { 0.1, 0.1, 0.7, 1.0 };
  58     GLfloat blue_specular[] = { 0.1, 1.0, 1.0, 1.0 };
  59
  60     GLfloat position_one[] = { 1.0, 1.0, 1.0, 0.0 };
  61
  62     glNewList(YELLOWMAT, GL_COMPILE);
  63     glMaterialfv(GL_FRONT, GL_DIFFUSE, yellow_diffuse);
  64     glMaterialfv(GL_FRONT, GL_SPECULAR, yellow_specular);
  65     glMaterialf(GL_FRONT, GL_SHININESS, 64.0);
  66     glEndList();
  67
  68     glNewList(BLUEMAT, GL_COMPILE);
  69     glMaterialfv(GL_FRONT, GL_DIFFUSE, blue_diffuse);
  70     glMaterialfv(GL_FRONT, GL_SPECULAR, blue_specular);
  71     glMaterialf(GL_FRONT, GL_SHININESS, 45.0);
  72     glEndList();
  73
  74     glLightfv(GL_LIGHT0, GL_POSITION, position_one);
  75
  76     glEnable(GL_LIGHT0);
  77     glEnable(GL_LIGHTING);
  78     glDepthFunc(GL_LESS);
  79     glEnable(GL_DEPTH_TEST);
  80
  81     glClearStencil(0x0);
  82     glEnable(GL_STENCIL_TEST);
  83
  84 }
  85
  86 /*  Draw a sphere in a diamond-shaped section in the
  87  *  middle of a window with 2 tori.
  88  */
  89 void display(void)
  90 {
  91     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  92
  93 /* draw blue sphere where the stencil is 1 */
  94     glStencilFunc (GL_EQUAL, 0x1, 0x1);
  95     glCallList (BLUEMAT);
  96     glutSolidSphere (0.5, 15, 15);
  97
  98 /* draw the tori where the stencil is not 1 */
  99     glStencilFunc (GL_NOTEQUAL, 0x1, 0x1);
 100     glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP);
 101     glPushMatrix();
 102         glRotatef (45.0, 0.0, 0.0, 1.0);
 103         glRotatef (45.0, 0.0, 1.0, 0.0);
 104         glCallList (YELLOWMAT);
 105         glutSolidTorus (0.275, 0.85, 15, 15);
 106         glPushMatrix();
 107             glRotatef (90.0, 1.0, 0.0, 0.0);
 108             glutSolidTorus (0.275, 0.85, 15, 15);
 109         glPopMatrix();
 110     glPopMatrix();
 111
 112     glFlush();
 113 }
 114
 115 /*  Whenever the window is reshaped, redefine the
 116  *  coordinate system and redraw the stencil area.
 117  */
 118 void myReshape(int w, int h)
 119 {
 120     glViewport(0, 0, w, h);
 121
 122     glClear(GL_STENCIL_BUFFER_BIT);
 123 /* create a diamond shaped stencil area */
 124     glMatrixMode(GL_PROJECTION);
 125     glLoadIdentity();
 126     glOrtho(-3.0, 3.0, -3.0, 3.0, -1.0, 1.0);
 127     glMatrixMode(GL_MODELVIEW);
 128     glLoadIdentity();
 129
 130     glStencilFunc (GL_ALWAYS, 0x1, 0x1);
 131     glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE);
 132     glBegin(GL_QUADS);
 133         glVertex3f (-1.0, 0.0, 0.0);
 134         glVertex3f (0.0, 1.0, 0.0);
 135         glVertex3f (1.0, 0.0, 0.0);
 136         glVertex3f (0.0, -1.0, 0.0);
 137     glEnd();
 138
 139     glMatrixMode(GL_PROJECTION);
 140     glLoadIdentity();
 141     gluPerspective(45.0, (GLfloat) w/(GLfloat) h, 3.0, 7.0);
 142     glMatrixMode(GL_MODELVIEW);
 143     glLoadIdentity();
 144     glTranslatef(0.0, 0.0, -5.0);
 145 }
 146
 147 /*  Main Loop
 148  *  Open window with initial window size, title bar,
 149  *  RGBA display mode, and handle input events.
 150  */
 151 int main(int argc, char** argv)
 152 {
 153     glutInit(&argc, argv);
 154     glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH | GLUT_STENCIL);
 155     glutInitWindowSize (400, 400);
 156     glutCreateWindow (argv[0]);
 157     myinit ();
 158     glutReshapeFunc (myReshape);
 159     glutDisplayFunc(display);
 160     glutMainLoop();
 161     return 0;             /* ANSI C requires main to return int. */
 162 }