OpenGLUT 0.6.3 development - OpenGLUT: fog.c File Reference
Keywords: OpenGLUT, FreeGLUT, OpenGL, GLUT, X11, Windows, Programming, Documentation, Download, Development, Sourceforge

OpenGLUT Documentation
Introduction | Documentation | Examples | Proposals | Authors | Copying | Todo | Bugs | Links

# fog.c File Reference

## Detailed Description

This program draws 5 red teapots, each at a different z distance from the eye, in different types of fog.

Pressing the left mouse button chooses between 3 types of fog: exponential, exponential squared, and linear.

In this program, there is a fixed density value, as well as fixed start and end values for the linear fog.

    /* Copyright (c) Mark J. Kilgard, 1994. */

    /*
     * (c) Copyright 1993, 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(TM) is a trademark of Silicon Graphics, Inc.
     */

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

    GLint fogMode;

    void
    selectFog(int mode)
    {
        switch(mode) {
        case GL_LINEAR:
            glFogf(GL_FOG_START, 1.0);
            glFogf(GL_FOG_END, 5.0);
        /* falls through */
        case GL_EXP2:
        case GL_EXP:
        glFogiv(GL_FOG_MODE, (int *) &mode);
        glutPostRedisplay();
        break;
        case 0:
        exit(0);
        }
    }

    /*  Initialize z-buffer, projection matrix, light source,
     *  and lighting model.  Do not specify a material property here.
     */
    void
    myinit(void)
    {
        GLfloat position[] =
        {0.0, 3.0, 3.0, 0.0};
        GLfloat local_view[] =
        {0.0};

        glEnable(GL_DEPTH_TEST);
        glDepthFunc(GL_LESS);

        glLightfv(GL_LIGHT0, GL_POSITION, position);
        glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);

        glFrontFace(GL_CW);
        glEnable(GL_LIGHTING);
        glEnable(GL_LIGHT0);
        glEnable(GL_AUTO_NORMAL);
        glEnable(GL_NORMALIZE);
        glEnable(GL_FOG);
        {
            GLfloat fogColor[4] =
            {0.5, 0.5, 0.5, 1.0};

            fogMode = GL_EXP;
            glFogi(GL_FOG_MODE, fogMode);
            glFogfv(GL_FOG_COLOR, fogColor);
            glFogf(GL_FOG_DENSITY, 0.35);
            glHint(GL_FOG_HINT, GL_DONT_CARE);
            glClearColor(0.5, 0.5, 0.5, 1.0);
        }
    }

    void
    renderRedTeapot(GLfloat x, GLfloat y, GLfloat z)
    {
        float mat[4];

        glPushMatrix();
        glTranslatef(x, y, z);
        mat[0] = 0.1745;
        mat[1] = 0.01175;
        mat[2] = 0.01175;
        mat[3] = 1.0;
        glMaterialfv(GL_FRONT, GL_AMBIENT, mat);
        mat[0] = 0.61424;
        mat[1] = 0.04136;
        mat[2] = 0.04136;
        glMaterialfv(GL_FRONT, GL_DIFFUSE, mat);
        mat[0] = 0.727811;
        mat[1] = 0.626959;
        mat[2] = 0.626959;
        glMaterialfv(GL_FRONT, GL_SPECULAR, mat);
        glMaterialf(GL_FRONT, GL_SHININESS, 0.6 * 128.0);
        glutSolidTeapot(1.0);
        glPopMatrix();
    }

    /*  display() draws 5 teapots at different z positions.
     */
    void
    display(void)
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        renderRedTeapot(-4.0, -0.5, -1.0);
        renderRedTeapot(-2.0, -0.5, -2.0);
        renderRedTeapot(0.0, -0.5, -3.0);
        renderRedTeapot(2.0, -0.5, -4.0);
        renderRedTeapot(4.0, -0.5, -5.0);
        glFlush();
    }

    void
    myReshape(int w, int h)
    {
        glViewport(0, 0, w, h);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        if (w <= (h * 3))
            glOrtho(-6.0, 6.0, -2.0 * ((GLfloat) h * 3) / (GLfloat) w,
                2.0 * ((GLfloat) h * 3) / (GLfloat) w, 0.0, 10.0);
        else
            glOrtho(-6.0 * (GLfloat) w / ((GLfloat) h * 3),
                6.0 * (GLfloat) w / ((GLfloat) h * 3), -2.0, 2.0, 0.0, 10.0);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
    }

    static void
    key(unsigned char k, int x, int y)
    {
      switch (k) {
      case 27:  /* Escape */
        exit(0);
        break;
      default:
        return;
      }
      glutPostRedisplay();
    }

    /*  Main Loop
     *  Open window with initial window size, title bar,
     *  RGBA display mode, depth buffer, and handle input events.
     */
    int
    main(int argc, char **argv)
    {
        glutInit(&argc, argv);
        glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
        glutInitWindowSize(450, 150);
        glutCreateWindow(argv[0]);
        myinit();
        glutReshapeFunc(myReshape);
        glutDisplayFunc(display);
        glutCreateMenu(selectFog);
        glutAddMenuEntry("Fog EXP", GL_EXP);
        glutAddMenuEntry("Fog EXP2", /*GL_EXP2*/ 0xffff);
        glutAddMenuEntry("Fog LINEAR", GL_LINEAR);
        glutAddMenuEntry("Quit", 0);
        glutAttachMenu(GLUT_RIGHT_BUTTON);
        glutKeyboardFunc(key);
        glutMainLoop();
        return 0;             /* ANSI C requires main to return int. */
    }

OpenGLUT Development @ Sourceforge
Homepage | Summary | Files | CVS | Forums | Lists | Bugs | RFE
Generated on Tue Oct 5 18:44:21 2004 for OpenGLUT by doxygen 1.3.8
The OpenGLUT project is hosted by sourceforge.net.