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34 * Unpublished-- rights reserved under the copyright laws of the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
47/*
48 * !!! NOTE !!!
49 *
50 * This demo is poorly written.  The stencil buffer should be
51 * redrawn in display(), not in the myReshape() function.
52 * The reason is if the window gets "damaged" then the stencil buffer
53 * contents will be in an undefined state (myReshape is not called when
54 * a window is damaged and needs to be redrawn).  If the stencil buffer
55 * contents are undefined, the results of display() are unpredictable.
56 *
57 * -Brian
58 */
59
60
61#include <stdlib.h>
62#include "glut_wrap.h"
63
64#define YELLOWMAT   1
65#define BLUEMAT 2
66
67static void myinit (void)
68{
69    GLfloat yellow_diffuse[] = { 0.7, 0.7, 0.0, 1.0 };
70    GLfloat yellow_specular[] = { 1.0, 1.0, 1.0, 1.0 };
71
72    GLfloat blue_diffuse[] = { 0.1, 0.1, 0.7, 1.0 };
73    GLfloat blue_specular[] = { 0.1, 1.0, 1.0, 1.0 };
74
75    GLfloat position_one[] = { 1.0, 1.0, 1.0, 0.0 };
76
77    glNewList(YELLOWMAT, GL_COMPILE);
78    glMaterialfv(GL_FRONT, GL_DIFFUSE, yellow_diffuse);
79    glMaterialfv(GL_FRONT, GL_SPECULAR, yellow_specular);
80    glMaterialf(GL_FRONT, GL_SHININESS, 64.0);
81    glEndList();
82
83    glNewList(BLUEMAT, GL_COMPILE);
84    glMaterialfv(GL_FRONT, GL_DIFFUSE, blue_diffuse);
85    glMaterialfv(GL_FRONT, GL_SPECULAR, blue_specular);
86    glMaterialf(GL_FRONT, GL_SHININESS, 45.0);
87    glEndList();
88
89    glLightfv(GL_LIGHT0, GL_POSITION, position_one);
90
91    glEnable(GL_LIGHT0);
92    glEnable(GL_LIGHTING);
93    glDepthFunc(GL_LESS);
94    glEnable(GL_DEPTH_TEST);
95
96    glClearStencil(0x0);
97    glEnable(GL_STENCIL_TEST);
98
99}
100
101/*  Draw a sphere in a diamond-shaped section in the
102 *  middle of a window with 2 tori.
103 */
104static void display(void)
105{
106    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
107
108    glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP);
109
110/* draw blue sphere where the stencil is 1 */
111    glStencilFunc (GL_EQUAL, 0x1, 0x1);
112    glCallList (BLUEMAT);
113    glutSolidSphere (0.5, 15, 15);
114
115/* draw the tori where the stencil is not 1 */
116    glStencilFunc (GL_NOTEQUAL, 0x1, 0x1);
117    glPushMatrix();
118	glRotatef (45.0, 0.0, 0.0, 1.0);
119	glRotatef (45.0, 0.0, 1.0, 0.0);
120	glCallList (YELLOWMAT);
121	glutSolidTorus (0.275, 0.85, 15, 15);
122	glPushMatrix();
123	    glRotatef (90.0, 1.0, 0.0, 0.0);
124	    glutSolidTorus (0.275, 0.85, 15, 15);
125	glPopMatrix();
126    glPopMatrix();
127
128    glFlush();
129    glutSwapBuffers();
130}
131
132/*  Whenever the window is reshaped, redefine the
133 *  coordinate system and redraw the stencil area.
134 */
135static void myReshape(int w, int h)
136{
137    glViewport(0, 0, w, h);
138
139    glClear(GL_STENCIL_BUFFER_BIT);
140/* create a diamond shaped stencil area */
141    glMatrixMode(GL_PROJECTION);
142    glLoadIdentity();
143    glOrtho(-3.0, 3.0, -3.0, 3.0, -1.0, 1.0);
144    glMatrixMode(GL_MODELVIEW);
145    glLoadIdentity();
146
147    glStencilFunc (GL_ALWAYS, 0x1, 0x1);
148    glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE);
149    glBegin(GL_QUADS);
150	glVertex3f (-1.0, 0.0, 0.0);
151	glVertex3f (0.0, 1.0, 0.0);
152	glVertex3f (1.0, 0.0, 0.0);
153	glVertex3f (0.0, -1.0, 0.0);
154    glEnd();
155
156    glMatrixMode(GL_PROJECTION);
157    glLoadIdentity();
158    gluPerspective(45.0, (GLfloat) w/(GLfloat) h, 3.0, 7.0);
159    glMatrixMode(GL_MODELVIEW);
160    glLoadIdentity();
161    glTranslatef(0.0, 0.0, -5.0);
162}
163
164static void
165key(unsigned char k, int x, int y)
166{
167  switch (k) {
168  case 27:  /* Escape */
169    exit(0);
170    break;
171  default:
172    return;
173  }
174  glutPostRedisplay();
175}
176
177/*  Main Loop
178 *  Open window with initial window size, title bar,
179 *  RGBA display mode, and handle input events.
180 */
181int main(int argc, char** argv)
182{
183    glutInit(&argc, argv);
184    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH | GLUT_STENCIL);
185    glutInitWindowSize (400, 400);
186    glutCreateWindow (argv[0]);
187    myinit ();
188    glutReshapeFunc (myReshape);
189    glutDisplayFunc(display);
190    glutKeyboardFunc(key);
191    glutMainLoop();
192    return 0;             /* ANSI C requires main to return int. */
193}
194