progs/trivial/tri-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 }
  35
  36 static void Reshape(int width, int height)
  37 {
  38
  39     glViewport(0, 0, (GLint)width, (GLint)height);
  40
  41     glMatrixMode(GL_PROJECTION);
  42     glLoadIdentity();
  43     glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
  44     glMatrixMode(GL_MODELVIEW);
  45 }
  46
  47 static void Key(unsigned char key, int x, int y)
  48 {
  49
  50     switch (key) {
  51       case 27:
  52         printf("Exiting...\n");
  53         exit(1);
  54       case 'r':
  55         printf("Redisplaying...\n");
  56         glutPostRedisplay();
  57         break;
  58       default:
  59         printf("No such key '%c'...\n", key);
  60         break;
  61     }
  62 }
  63
  64 static void Draw(void)
  65 {
  66    glShadeModel(GL_FLAT);
  67
  68    {
  69       glClearColor(0.0, 0.0, 0.0, 0.0);
  70       glClearStencil(0);
  71       glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
  72    }
  73
  74
  75    glStencilMask(1);
  76    glEnable(GL_STENCIL_TEST);
  77    glStencilFunc(GL_ALWAYS, 1, 1);
  78    glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
  79
  80    glColor3ub(200, 0, 0);
  81    glBegin(GL_POLYGON);
  82    glVertex3i(-4, -4, 0);
  83    glVertex3i( 4, -4, 0);
  84    glVertex3i( 0,  4, 0);
  85    glEnd();
  86
  87 #if 1
  88    glStencilFunc(GL_EQUAL, 1, 1);
  89    glStencilOp(GL_INCR, GL_KEEP, GL_DECR);
  90
  91    glColor3ub(0, 200, 0);
  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 #endif
  99
 100 #if 1
 101    glStencilFunc(GL_EQUAL, 1, 1);
 102    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 103
 104    glColor3ub(0, 0, 200);
 105    glBegin(GL_POLYGON);
 106    glVertex3f(2.5, 2.5, 0);
 107    glVertex3f(-2.5, 2.5, 0);
 108    glVertex3f(-2.5, -2.5, 0);
 109    glVertex3f(2.5, -2.5, 0);
 110    glEnd();
 111 #endif
 112
 113    glFlush();
 114 }
 115
 116 static GLenum Args(int argc, char **argv)
 117 {
 118     GLint i;
 119
 120
 121     for (i = 1; i < argc; i++) {
 122         if (strcmp(argv[i], "-dr") == 0) {
 123         } else {
 124             printf("%s (Bad option).\n", argv[i]);
 125             return GL_FALSE;
 126         }
 127     }
 128     return GL_TRUE;
 129 }
 130
 131 int main(int argc, char **argv)
 132 {
 133     GLenum type;
 134
 135     glutInit(&argc, argv);
 136
 137     if (Args(argc, argv) == GL_FALSE) {
 138         exit(1);
 139     }
 140
 141     glutInitWindowPosition(0, 0);
 142     glutInitWindowSize( 300, 300);
 143
 144     type = GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH | GLUT_STENCIL;
 145     glutInitDisplayMode(type);
 146
 147     if (glutCreateWindow("Stencil Test") == GL_FALSE) {
 148         exit(1);
 149     }
 150
 151     Init();
 152
 153     glutReshapeFunc(Reshape);
 154     glutKeyboardFunc(Key);
 155     glutDisplayFunc(Draw);
 156     glutMainLoop();
 157         return 0;
 158 }