progs/samples/stencil.c

   1 /*
   2  * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and
   5  * its documentation for any purpose is hereby granted without fee, provided
   6  * that (i) the above copyright notices and this permission notice appear in
   7  * all copies of the software and related documentation, and (ii) the name of
   8  * Silicon Graphics may not be used in any advertising or
   9  * publicity relating to the software without the specific, prior written
  10  * permission of Silicon Graphics.
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
  13  * ANY KIND,
  14  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  15  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  16  *
  17  * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
  18  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  20  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  21  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  22  * OF THIS SOFTWARE.
  23  */
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <math.h>
  29 #include <GL/glut.h>
  30
  31
  32 static void Init(void)
  33 {
  34    glShadeModel(GL_FLAT);
  35     glClearColor(0.0, 0.0, 0.0, 0.0);
  36
  37     glClearStencil(0);
  38     glStencilMask(1);
  39     glEnable(GL_STENCIL_TEST);
  40 }
  41
  42 static void Reshape(int width, int height)
  43 {
  44
  45     glViewport(0, 0, (GLint)width, (GLint)height);
  46
  47     glMatrixMode(GL_PROJECTION);
  48     glLoadIdentity();
  49     glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
  50     glMatrixMode(GL_MODELVIEW);
  51 }
  52
  53 static void Key(unsigned char key, int x, int y)
  54 {
  55
  56     switch (key) {
  57       case 27:
  58         exit(1);
  59     }
  60 }
  61
  62 static void Draw(void)
  63 {
  64
  65     glClear(GL_COLOR_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
  66
  67     glStencilFunc(GL_ALWAYS, 1, 1);
  68     glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
  69
  70     glColor3ub(200, 0, 0);
  71     glBegin(GL_POLYGON);
  72         glVertex3i(-4, -4, 0);
  73         glVertex3i( 4, -4, 0);
  74         glVertex3i( 0,  4, 0);
  75     glEnd();
  76
  77     glStencilFunc(GL_EQUAL, 1, 1);
  78     glStencilOp(GL_INCR, GL_KEEP, GL_DECR);
  79
  80     glColor3ub(0, 200, 0);
  81     glBegin(GL_POLYGON);
  82         glVertex3i(3, 3, 0);
  83         glVertex3i(-3, 3, 0);
  84         glVertex3i(-3, -3, 0);
  85         glVertex3i(3, -3, 0);
  86     glEnd();
  87
  88     glStencilFunc(GL_EQUAL, 1, 1);
  89     glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
  90
  91     glColor3ub(0, 0, 200);
  92     glBegin(GL_POLYGON);
  93         glVertex3i(3, 3, 0);
  94         glVertex3i(-3, 3, 0);
  95         glVertex3i(-3, -3, 0);
  96         glVertex3i(3, -3, 0);
  97     glEnd();
  98
  99     glFlush();
 100 }
 101
 102 static GLenum Args(int argc, char **argv)
 103 {
 104     GLint i;
 105
 106
 107     for (i = 1; i < argc; i++) {
 108         if (strcmp(argv[i], "-dr") == 0) {
 109         } else {
 110             printf("%s (Bad option).\n", argv[i]);
 111             return GL_FALSE;
 112         }
 113     }
 114     return GL_TRUE;
 115 }
 116
 117 int main(int argc, char **argv)
 118 {
 119     GLenum type;
 120
 121     glutInit(&argc, argv);
 122
 123     if (Args(argc, argv) == GL_FALSE) {
 124         exit(1);
 125     }
 126
 127     glutInitWindowPosition(0, 0); glutInitWindowSize( 300, 300);
 128
 129     type = GLUT_RGB | GLUT_SINGLE | GLUT_STENCIL;
 130     glutInitDisplayMode(type);
 131
 132     if (glutCreateWindow("Stencil Test") == GL_FALSE) {
 133         exit(1);
 134     }
 135
 136     Init();
 137
 138     glutReshapeFunc(Reshape);
 139     glutKeyboardFunc(Key);
 140     glutDisplayFunc(Draw);
 141     glutMainLoop();
 142         return 0;
 143 }