OpenGLUT 0.6.3 development - OpenGLUT: alpha3D.c File Reference
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# alpha3D.c File Reference

## Detailed Description

This program demonstrates how to intermix opaque and alpha blended polygons in the same scene, by using glDepthMask.

Press the 'a' key to animate moving the transparent object through the opaque object.

Press the 'r' key to reset the scene.

    /*
     * Copyright (c) 1993-1997, Silicon Graphics, Inc.
     * ALL RIGHTS RESERVED
     * Permission to use, copy, modify, and distribute this software for
     * any purpose and without fee is hereby granted, provided that the above
     * copyright notice appear in all copies and that both the copyright notice
     * and this permission notice appear in supporting documentation, and that
     * the name of Silicon Graphics, Inc. not be used in advertising
     * or publicity pertaining to distribution of the software without specific,
     * written prior permission.
     *
     * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
     * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
     * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
     * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
     * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
     * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
     * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
     * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
     * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
     * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
     * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
     * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
     *
     * US Government Users Restricted Rights
     * Use, duplication, or disclosure by the Government is subject to
     * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
     * (c)(1)(ii) of the Rights in Technical Data and Computer Software
     * clause at DFARS 252.227-7013 and/or in similar or successor
     * clauses in the FAR or the DOD or NASA FAR Supplement.
     * Unpublished-- rights reserved under the copyright laws of the
     * United States.  Contractor/manufacturer is Silicon Graphics,
     * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
     *
     * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
     */

    #include <GL/openglut.h>
    #include <stdlib.h>
    #include <stdio.h>

    #define MAXZ 8.0
    #define MINZ -8.0
    #define ZINC 0.4

    static float solidZ = MAXZ;
    static float transparentZ = MINZ;
    static GLuint sphereList, cubeList;

    static void init(void)
    {
       GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 0.15 };
       GLfloat mat_shininess[] = { 100.0 };
       GLfloat position[] = { 0.5, 0.5, 1.0, 0.0 };

       glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
       glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
       glLightfv(GL_LIGHT0, GL_POSITION, position);

       glEnable(GL_LIGHTING);
       glEnable(GL_LIGHT0);
       glEnable(GL_DEPTH_TEST);

       sphereList = glGenLists(1);
       glNewList(sphereList, GL_COMPILE);
          glutSolidSphere (0.4, 16, 16);
       glEndList();

       cubeList = glGenLists(1);
       glNewList(cubeList, GL_COMPILE);
          glutSolidCube (0.6);
       glEndList();
    }

    void display(void)
    {
       GLfloat mat_solid[] = { 0.75, 0.75, 0.0, 1.0 };
       GLfloat mat_zero[] = { 0.0, 0.0, 0.0, 1.0 };
       GLfloat mat_transparent[] = { 0.0, 0.8, 0.8, 0.6 };
       GLfloat mat_emission[] = { 0.0, 0.3, 0.3, 0.6 };

       glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

       glPushMatrix ();
          glTranslatef (-0.15, -0.15, solidZ);
          glMaterialfv(GL_FRONT, GL_EMISSION, mat_zero);
          glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_solid);
          glCallList (sphereList);
       glPopMatrix ();

       glPushMatrix ();
          glTranslatef (0.15, 0.15, transparentZ);
          glRotatef (15.0, 1.0, 1.0, 0.0);
          glRotatef (30.0, 0.0, 1.0, 0.0);
          glMaterialfv(GL_FRONT, GL_EMISSION, mat_emission);
          glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_transparent);
          glEnable (GL_BLEND);
          glDepthMask (GL_FALSE);
          glBlendFunc (GL_SRC_ALPHA, GL_ONE);
          glCallList (cubeList);
          glDepthMask (GL_TRUE);
          glDisable (GL_BLEND);
       glPopMatrix ();

       glutSwapBuffers();
    }

    void reshape(int w, int h)
    {
       glViewport(0, 0, (GLint) w, (GLint) h);
       glMatrixMode(GL_PROJECTION);
       glLoadIdentity();
       if (w <= h)
          glOrtho (-1.5, 1.5, -1.5*(GLfloat)h/(GLfloat)w,
                   1.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
       else
          glOrtho (-1.5*(GLfloat)w/(GLfloat)h,
                   1.5*(GLfloat)w/(GLfloat)h, -1.5, 1.5, -10.0, 10.0);
       glMatrixMode(GL_MODELVIEW);
       glLoadIdentity();
    }

    void animate(void)
    {
       if (solidZ <= MINZ || transparentZ >= MAXZ)
          glutIdleFunc(NULL);
       else {
          solidZ -= ZINC;
          transparentZ += ZINC;
          glutPostRedisplay();
       }
    }

    /* ARGSUSED1 */
    void keyboard(unsigned char key, int x, int y)
    {
       switch (key) {
          case 'a':
          case 'A':
             solidZ = MAXZ;
             transparentZ = MINZ;
             glutIdleFunc(animate);
             break;
          case 'r':
          case 'R':
             solidZ = MAXZ;
             transparentZ = MINZ;
             glutPostRedisplay();
             break;
          case 27:
            exit(0);
        }
    }

    int main(int argc, char** argv)
    {
       glutInit(&argc, argv);
       glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
       glutInitWindowSize(500, 500);
       glutCreateWindow(argv[0]);
       init();
       glutReshapeFunc(reshape);
       glutKeyboardFunc(keyboard);
       glutDisplayFunc(display);
       glutMainLoop();
       return 0;
    }

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