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  31  * Unpublished-- rights reserved under the copyright laws of the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 static float minZ = 0.0;
  61 static float maxZ = 1.0;
  62
  63 static void usage(void)
  64 {
  65    printf("t   - toggle rendering order of triangles\n");
  66    printf("c   - toggle Z clear value between 0, 1\n");
  67    printf("f   - cycle through depth test functions\n");
  68    printf("n/N - decrease/increase depthrange minZ\n");
  69    printf("x/X - decrease/increase depthrange maxZ\n");
  70    printf("spc - reset\n");
  71    printf("z   - set to reverse-direction (ztrick) mode\n");
  72    fflush(stdout);
  73 }
  74
  75
  76 static void init(void)
  77 {
  78    glEnable(GL_DEPTH_TEST);
  79    glClearColor (1.0, 0.0, 0.0, 0.0);
  80 }
  81
  82 static void drawLeftTriangle(void)
  83 {
  84    /* draw yellow triangle on LHS of screen */
  85    glBegin (GL_TRIANGLES);
  86       glColor4f(1.0, 1.0, 0.0, 0.75);
  87       glVertex3f(0.1, 0.9, -1.0);
  88       glVertex3f(0.1, 0.1, -1.0);
  89       glVertex3f(0.8, 0.5,  1.0);
  90    glEnd();
  91 }
  92
  93 static void drawRightTriangle(void)
  94 {
  95    /* draw cyan triangle on RHS of screen */
  96    glBegin (GL_TRIANGLES);
  97       glColor4f(0.0, 1.0, 1.0, 0.75);
  98       glVertex3f(0.9, 0.9, 0.0);
  99       glVertex3f(0.2, 0.5, 0.0);
 100       glVertex3f(0.9, 0.1, 0.0);
 101    glEnd();
 102 }
 103
 104 static void display(void)
 105 {
 106    printf("GL_CLEAR_DEPTH = %.2f,  GL_DEPTH_FUNC = %s,  DepthRange(%.1f, %.1f)\n",
 107           clearVal, funcs[curFunc].str, minZ, maxZ);
 108    fflush(stdout);
 109    glClearDepth(clearVal);
 110    glDepthRange(minZ, maxZ);
 111    glDepthFunc(funcs[curFunc].func);
 112
 113    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 114
 115    if (leftFirst) {
 116       drawLeftTriangle();
 117       drawRightTriangle();
 118    }
 119    else {
 120       drawRightTriangle();
 121       drawLeftTriangle();
 122    }
 123
 124    glFlush();
 125 }
 126
 127 static void reshape(int w, int h)
 128 {
 129    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
 130    glMatrixMode(GL_PROJECTION);
 131    glLoadIdentity();
 132    if (w <= h)
 133       gluOrtho2D (0.0, 1.0, 0.0, 1.0*(GLfloat)h/(GLfloat)w);
 134    else
 135       gluOrtho2D (0.0, 1.0*(GLfloat)w/(GLfloat)h, 0.0, 1.0);
 136 }
 137
 138 /* ARGSUSED1 */
 139 static void keyboard(unsigned char key, int x, int y)
 140 {
 141    switch (key) {
 142       case 'n':
 143          minZ -= .1;
 144          break;
 145       case 'N':
 146          minZ += .1;
 147          break;
 148       case 'x':
 149          maxZ -= .1;
 150          break;
 151       case 'X':
 152          maxZ += .1;
 153          break;
 154       case 'c':
 155       case 'C':
 156          clearVal = 1.0 - clearVal;
 157          break;
 158       case 'f':
 159       case 'F':
 160          curFunc = (curFunc + 1) % NUM_FUNCS;
 161          break;
 162       case 't':
 163       case 'T':
 164          leftFirst = !leftFirst;
 165          break;
 166       case ' ':
 167          curFunc = 0;
 168          clearVal = 1.0;
 169          minZ = 0.0;
 170          maxZ = 1.0;
 171          break;
 172       case 'z':
 173          curFunc = 2;
 174          clearVal = 0.0;
 175          minZ = 1.0;
 176          maxZ = 0.0;
 177          break;
 178       case 27:  /*  Escape key  */
 179          exit(0);
 180          break;
 181       default:
 182          return;
 183    }
 184    glutPostRedisplay();
 185 }
 186
 187 /*  Main Loop
 188  *  Open window with initial window size, title bar,
 189  *  RGBA display mode, and handle input events.
 190  */
 191 int main(int argc, char** argv)
 192 {
 193    glutInit(&argc, argv);
 194    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 195    glutInitWindowSize (200, 200);
 196    glutCreateWindow (argv[0]);
 197    glutReshapeFunc (reshape);
 198    glutKeyboardFunc (keyboard);
 199    glutDisplayFunc (display);
 200    init();
 201    usage();
 202    glutMainLoop();
 203    return 0;
 204 }