progs/trivial/tri-z.c

   1 /*
   2  * Copyright (c) 1993-1997, Silicon Graphics, Inc.
   3  * ALL RIGHTS RESERVED
   4  * Permission to use, copy, modify, and distribute this software for
   5  * any purpose and without fee is hereby granted, provided that the above
   6  * copyright notice appear in all copies and that both the copyright notice
   7  * and this permission notice appear in supporting documentation, and that
   8  * the name of Silicon Graphics, Inc. not be used in advertising
   9  * or publicity pertaining to distribution of the software without specific,
  10  * written prior permission.
  11  *
  12  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
  13  * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  14  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  15  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  16  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  17  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
  18  * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
  19  * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
  20  * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
  21  * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
  22  * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
  23  * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
  24  *
  25  * US Government Users Restricted Rights
  26  * Use, duplication, or disclosure by the Government is subject to
  27  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  28  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  29  * clause at DFARS 252.227-7013 and/or in similar or successor
  30  * clauses in the FAR or the DOD or NASA FAR Supplement.
  31  * Unpublished-- rights reserved under the copyright laws of the
  32  * United States.  Contractor/manufacturer is Silicon Graphics,
  33  * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
  34  *
  35  * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
  36  */
  37
  38 #include <GL/glut.h>
  39 #include <stdlib.h>
  40 #include <stdio.h>
  41
  42 static int leftFirst = GL_TRUE;
  43
  44 static struct { GLenum func; const char *str; } funcs[] =
  45    {
  46       { GL_LESS, "GL_LESS" },
  47       { GL_LEQUAL, "GL_LEQUAL" },
  48       { GL_GREATER, "GL_GREATER" },
  49       { GL_GEQUAL, "GL_GEQUAL" },
  50       { GL_EQUAL, "GL_EQUAL" },
  51       { GL_NOTEQUAL, "GL_NOTEQUAL" },
  52       { GL_ALWAYS, "GL_ALWAYS" },
  53       { GL_NEVER, "GL_NEVER" },
  54    };
  55
  56 #define NUM_FUNCS (sizeof(funcs) / sizeof(funcs[0]))
  57
  58 static int curFunc = 0;
  59 static double clearVal = 1.0;
  60
  61
  62 static void usage(void)
  63 {
  64    printf("t - toggle rendering order of triangles\n");
  65    printf("c - toggle Z clear value between 0, 1\n");
  66    printf("f - cycle through depth test functions\n");
  67 }
  68
  69
  70 static void init(void)
  71 {
  72    glEnable(GL_DEPTH_TEST);
  73    glClearColor (1.0, 0.0, 0.0, 0.0);
  74 }
  75
  76 static void drawLeftTriangle(void)
  77 {
  78    /* draw yellow triangle on LHS of screen */
  79    glBegin (GL_TRIANGLES);
  80       glColor4f(1.0, 1.0, 0.0, 0.75);
  81       glVertex3f(0.1, 0.9, -1.0);
  82       glVertex3f(0.1, 0.1, -1.0);
  83       glVertex3f(0.8, 0.5,  1.0);
  84    glEnd();
  85 }
  86
  87 static void drawRightTriangle(void)
  88 {
  89    /* draw cyan triangle on RHS of screen */
  90    glBegin (GL_TRIANGLES);
  91       glColor4f(0.0, 1.0, 1.0, 0.75);
  92       glVertex3f(0.9, 0.9, 0.0);
  93       glVertex3f(0.2, 0.5, 0.0);
  94       glVertex3f(0.9, 0.1, 0.0);
  95    glEnd();
  96 }
  97
  98 void display(void)
  99 {
 100    printf("GL_CLEAR_DEPTH = %f  GL_DEPTH_FUNC = %s\n",
 101           clearVal, funcs[curFunc].str);
 102    glClearDepth(clearVal);
 103    glDepthFunc(funcs[curFunc].func);
 104
 105    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 106
 107    if (leftFirst) {
 108       drawLeftTriangle();
 109       drawRightTriangle();
 110    }
 111    else {
 112       drawRightTriangle();
 113       drawLeftTriangle();
 114    }
 115
 116    glFlush();
 117 }
 118
 119 void reshape(int w, int h)
 120 {
 121    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
 122    glMatrixMode(GL_PROJECTION);
 123    glLoadIdentity();
 124    if (w <= h)
 125       gluOrtho2D (0.0, 1.0, 0.0, 1.0*(GLfloat)h/(GLfloat)w);
 126    else
 127       gluOrtho2D (0.0, 1.0*(GLfloat)w/(GLfloat)h, 0.0, 1.0);
 128 }
 129
 130 /* ARGSUSED1 */
 131 void keyboard(unsigned char key, int x, int y)
 132 {
 133    switch (key) {
 134       case 'c':
 135       case 'C':
 136          clearVal = 1.0 - clearVal;
 137          glutPostRedisplay();
 138          break;
 139       case 'f':
 140       case 'F':
 141          curFunc = (curFunc + 1) % NUM_FUNCS;
 142          glutPostRedisplay();
 143          break;
 144       case 't':
 145       case 'T':
 146          leftFirst = !leftFirst;
 147          glutPostRedisplay();
 148          break;
 149       case 27:  /*  Escape key  */
 150          exit(0);
 151          break;
 152       default:
 153          break;
 154    }
 155 }
 156
 157 /*  Main Loop
 158  *  Open window with initial window size, title bar,
 159  *  RGBA display mode, and handle input events.
 160  */
 161 int main(int argc, char** argv)
 162 {
 163    glutInit(&argc, argv);
 164    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 165    glutInitWindowSize (200, 200);
 166    glutCreateWindow (argv[0]);
 167    glutReshapeFunc (reshape);
 168    glutKeyboardFunc (keyboard);
 169    glutDisplayFunc (display);
 170    init();
 171    usage();
 172    glutMainLoop();
 173    return 0;
 174 }