src/redbook/alpha3D.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  31  * Unpublished-- rights reserved under the copyright laws of the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 /*
  39  *  alpha3D.c
  40  *  This program demonstrates how to intermix opaque and
  41  *  alpha blended polygons in the same scene, by using
  42  *  glDepthMask.  Press the 'a' key to animate moving the
  43  *  transparent object through the opaque object.  Press
  44  *  the 'r' key to reset the scene.
  45  */
  46 #include <stdlib.h>
  47 #include <stdio.h>
  48 #include <GL/glut.h>
  49
  50 #define MAXZ 8.0
  51 #define MINZ -8.0
  52 #define ZINC 4.
  53
  54 static float solidZ = MAXZ;
  55 static float transparentZ = MINZ;
  56 static GLuint sphereList, cubeList;
  57
  58 static void init(void)
  59 {
  60    GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 0.15 };
  61    GLfloat mat_shininess[] = { 100.0 };
  62    GLfloat position[] = { 0.5, 0.5, 1.0, 0.0 };
  63
  64    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
  65    glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
  66    glLightfv(GL_LIGHT0, GL_POSITION, position);
  67
  68    glEnable(GL_LIGHTING);
  69    glEnable(GL_LIGHT0);
  70    glEnable(GL_DEPTH_TEST);
  71
  72    sphereList = glGenLists(1);
  73    glNewList(sphereList, GL_COMPILE);
  74       glutSolidSphere (0.4, 16, 16);
  75    glEndList();
  76
  77    cubeList = glGenLists(1);
  78    glNewList(cubeList, GL_COMPILE);
  79       glutSolidCube (0.6);
  80    glEndList();
  81 }
  82
  83 void display(void)
  84 {
  85    GLfloat mat_solid[] = { 0.75, 0.75, 0.0, 1.0 };
  86    GLfloat mat_zero[] = { 0.0, 0.0, 0.0, 1.0 };
  87    GLfloat mat_transparent[] = { 0.0, 0.8, 0.8, 0.6 };
  88    GLfloat mat_emission[] = { 0.0, 0.3, 0.3, 0.6 };
  89
  90    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  91
  92    glPushMatrix ();
  93       glTranslatef (-0.15, -0.15, solidZ);
  94       glMaterialfv(GL_FRONT, GL_EMISSION, mat_zero);
  95       glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_solid);
  96       glCallList (sphereList);
  97    glPopMatrix ();
  98
  99    glPushMatrix ();
 100       glTranslatef (0.15, 0.15, transparentZ);
 101       glRotatef (15.0, 1.0, 1.0, 0.0);
 102       glRotatef (30.0, 0.0, 1.0, 0.0);
 103       glMaterialfv(GL_FRONT, GL_EMISSION, mat_emission);
 104       glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_transparent);
 105       glEnable (GL_BLEND);
 106       glDepthMask (GL_FALSE);
 107       glBlendFunc (GL_SRC_ALPHA, GL_ONE);
 108       glCallList (cubeList);
 109       glDepthMask (GL_TRUE);
 110       glDisable (GL_BLEND);
 111    glPopMatrix ();
 112
 113    glutSwapBuffers();
 114 }
 115
 116 void reshape(int w, int h)
 117 {
 118    glViewport(0, 0, (GLint) w, (GLint) h);
 119    glMatrixMode(GL_PROJECTION);
 120    glLoadIdentity();
 121    if (w <= h)
 122       glOrtho (-1.5, 1.5, -1.5*(GLfloat)h/(GLfloat)w,
 123                1.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
 124    else
 125       glOrtho (-1.5*(GLfloat)w/(GLfloat)h,
 126                1.5*(GLfloat)w/(GLfloat)h, -1.5, 1.5, -10.0, 10.0);
 127    glMatrixMode(GL_MODELVIEW);
 128    glLoadIdentity();
 129 }
 130
 131 void animate(void)
 132 {
 133    static double t0 = -1.;
 134    if (solidZ <= MINZ || transparentZ >= MAXZ)
 135    {
 136       glutIdleFunc(NULL);
 137       t0 = -1.;
 138    }
 139    else {
 140       double t, dt;
 141       t = glutGet(GLUT_ELAPSED_TIME) / 1000.;
 142       if (t0 < 0.)
 143          t0 = t;
 144       dt = t - t0;
 145       t0 = t;
 146       solidZ -= ZINC*dt;
 147       transparentZ += ZINC*dt;
 148       glutPostRedisplay();
 149    }
 150 }
 151
 152 /* ARGSUSED1 */
 153 void keyboard(unsigned char key, int x, int y)
 154 {
 155    switch (key) {
 156       case 'a':
 157       case 'A':
 158          solidZ = MAXZ;
 159          transparentZ = MINZ;
 160          glutIdleFunc(animate);
 161          break;
 162       case 'r':
 163       case 'R':
 164          solidZ = MAXZ;
 165          transparentZ = MINZ;
 166          glutPostRedisplay();
 167          break;
 168       case 27:
 169         exit(0);
 170     }
 171 }
 172
 173 int main(int argc, char** argv)
 174 {
 175    glutInit(&argc, argv);
 176    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
 177    glutInitWindowSize(500, 500);
 178    glutCreateWindow(argv[0]);
 179    init();
 180    glutReshapeFunc(reshape);
 181    glutKeyboardFunc(keyboard);
 182    glutDisplayFunc(display);
 183    glutMainLoop();
 184    return 0;
 185 }