progs/trivial/tri-cull.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 <string.h>
  27 #include <stdlib.h>
  28 #include <GL/glut.h>
  29
  30 static GLenum doubleBuffer;
  31 static GLint cullmode = 0;
  32
  33 static void cull(void)
  34 {
  35    cullmode = (cullmode + 1) % 4;
  36    if (cullmode == 0) {
  37       glCullFace(GL_FRONT);
  38       glEnable(GL_CULL_FACE);
  39       printf("cull GL_FRONT\n");
  40    }
  41    else if (cullmode == 1) {
  42       glCullFace(GL_BACK);
  43       glEnable(GL_CULL_FACE);
  44       printf("cull GL_BACK\n");
  45    }
  46    else if (cullmode == 2) {
  47       glCullFace(GL_FRONT_AND_BACK);
  48       glEnable(GL_CULL_FACE);
  49       printf("cull GL_FRONT_AND_BACK\n");
  50    }
  51    else {
  52       glDisable(GL_CULL_FACE);
  53       printf("cull none\n");
  54    }
  55 }
  56
  57 static void Init(void)
  58 {
  59    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
  60    fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
  61    fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
  62    glClearColor(0.0, 0.0, 1.0, 0.0);
  63    cull();
  64 }
  65
  66 static void Reshape(int width, int height)
  67 {
  68     glViewport(0, 0, (GLint)width, (GLint)height);
  69
  70     glMatrixMode(GL_PROJECTION);
  71     glLoadIdentity();
  72     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  73     glMatrixMode(GL_MODELVIEW);
  74 }
  75
  76 static void Key(unsigned char key, int x, int y)
  77 {
  78    switch (key) {
  79     case 27:
  80        exit(1);
  81    case 'c':
  82       cull();
  83       break;
  84    default:
  85       return;
  86    }
  87    glutPostRedisplay();
  88 }
  89
  90 static void Draw(void)
  91 {
  92    glClear(GL_COLOR_BUFFER_BIT);
  93
  94    glBegin(GL_TRIANGLES);
  95    /* back-facing */
  96    glColor3f(0,0,.7);
  97    glVertex3f(-0.1, -0.9, -30.0);
  98    glColor3f(.8,0,0);
  99    glVertex3f(-0.1,  0.9, -30.0);
 100    glColor3f(0,.9,0);
 101    glVertex3f(-0.9,  0.0, -30.0);
 102
 103    /* front-facing */
 104    glColor3f(0,0,.7);
 105    glVertex3f( 0.1, -0.9, -30.0);
 106    glColor3f(.8,0,0);
 107    glVertex3f( 0.1,  0.9, -30.0);
 108    glColor3f(0,.9,0);
 109    glVertex3f( 0.9,  0.0, -30.0);
 110
 111    glEnd();
 112
 113    glFlush();
 114
 115    if (doubleBuffer) {
 116       glutSwapBuffers();
 117    }
 118 }
 119
 120 static GLenum Args(int argc, char **argv)
 121 {
 122     GLint i;
 123
 124     doubleBuffer = GL_FALSE;
 125
 126     for (i = 1; i < argc; i++) {
 127         if (strcmp(argv[i], "-sb") == 0) {
 128             doubleBuffer = GL_FALSE;
 129         } else if (strcmp(argv[i], "-db") == 0) {
 130             doubleBuffer = GL_TRUE;
 131         } else {
 132             fprintf(stderr, "%s (Bad option).\n", argv[i]);
 133             return GL_FALSE;
 134         }
 135     }
 136     return GL_TRUE;
 137 }
 138
 139 int main(int argc, char **argv)
 140 {
 141     GLenum type;
 142
 143     glutInit(&argc, argv);
 144
 145     if (Args(argc, argv) == GL_FALSE) {
 146         exit(1);
 147     }
 148
 149     glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
 150
 151     type = GLUT_RGB | GLUT_ALPHA;
 152     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 153     glutInitDisplayMode(type);
 154
 155     if (glutCreateWindow("First Tri") == GL_FALSE) {
 156         exit(1);
 157     }
 158
 159     Init();
 160
 161     glutReshapeFunc(Reshape);
 162     glutKeyboardFunc(Key);
 163     glutDisplayFunc(Draw);
 164     glutMainLoop();
 165     return 0;
 166 }