SGI Developer Toolbox 6.1/SGI Developer Toolbox 6.1 - Disc 1.iso/toolbox/src/tutorials/custEducation/opengl2/examples/clipplanes/cutout.c

C/C++ Source or Header | 1996-11-11 | 4.7 KB | 201 lines

/*
 * Copyright 1993, 1995, Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;
 * the contents of this file may not be disclosed to third parties, copied or
 * duplicated in any form, in whole or in part, without the prior written
 * permission of Silicon Graphics, Inc.
 *
 * RESTRICTED RIGHTS LEGEND:
 * Use, duplication or disclosure by the Government is subject to restrictions
 * as set forth in subdivision (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, DOD or NASA FAR Supplement. Unpublished -
 * rights reserved under the Copyright Laws of the United States.
 */

/* cutout.c
 *     This program demonstrates how to use multiple
 *     clipping planes to cut a hole out of an object.
 *
 *     ESCAPE key    - exits program
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include <math.h>
#include <stdio.h>

/* Function Prototypes */

GLvoid  initgfx( GLvoid );
GLvoid  drawScene( GLvoid );
GLvoid  reshape( GLsizei, GLsizei );
GLvoid  animate( GLvoid );
GLvoid  visibility( GLint );
GLvoid  keyboard( GLubyte, GLint, GLint );

GLvoid  drawTorusRing( GLboolean );

void printHelp( char * );

/* Global Definitions */

#define KEY_ESC    27    /* ascii value for the escape key */

/* Global Variables */

static GLfloat angle = 0.0;

GLvoid
main( int argc, char *argv[] )
{
    GLsizei  width, height, winSize;

    glutInit( &argc, argv );

    width = glutGet(GLUT_SCREEN_WIDTH);
    height = glutGet(GLUT_SCREEN_HEIGHT);
    winSize = ( width < height ) ? width : height;
    glutInitWindowPosition( winSize/4, winSize/4 );
    glutInitWindowSize( winSize/2, winSize/2 );
    glutInitDisplayMode( GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE );
    glutCreateWindow( argv[0] );

    initgfx();

    glutKeyboardFunc( keyboard );
    glutReshapeFunc( reshape );
    glutIdleFunc( animate );
    glutVisibilityFunc( visibility );
    glutDisplayFunc( drawScene );

    printHelp( argv[0] );
    glutMainLoop();
}

GLvoid
printHelp( char *progname )
{
    fprintf(stdout, "\n%s - demonstrates how to use multiple "
        "clipping planes\nto create a cutout in a sphere.\n\n"
        "Escape key    - exit the program \n\n",
        progname );
}

void
initgfx( void )
{
    GLfloat front_diffuse[] = { 1.0, 0.1, 0.1, 1.0};
    GLfloat back_diffuse[] = { 0.1, 1.0, 0.1, 1.0};
    GLfloat mat_specular[] = { 0.8, 0.8, 0.8, 1.0 };
    GLfloat mat_shininess[] = { 40.0 };

    glMaterialfv(GL_FRONT, GL_DIFFUSE, front_diffuse);
    glMaterialfv(GL_BACK, GL_DIFFUSE, back_diffuse);

    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, mat_specular);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, mat_shininess);

    glLightModelf(GL_LIGHT_MODEL_TWO_SIDE, 1.0);

    glEnable( GL_LIGHTING );
    glEnable( GL_LIGHT0 );

    glClearColor( 0, 0, 0, 1 );
    glEnable( GL_DEPTH_TEST );
}

GLvoid
keyboard( GLubyte key, GLint x, GLint y )
{
    switch (key) {
    case KEY_ESC:    /* Exit whenever the Escape key is pressed */
        exit(0);
    }
}

GLvoid
reshape( GLsizei width, GLsizei height )
{
    GLdouble    aspect;

    glViewport( 0, 0, width, height );

    aspect = (GLdouble) width / (GLdouble) height;

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    gluPerspective( 45.0, aspect, 3.0, 13.0 );
    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();
    glTranslatef( 0.0, 0.0, -8.0 );
}

GLvoid
animate( GLvoid )
{
    /* update the current angle */
    angle = fmodf( (angle - 1.0), 360.0 );

    /* Tell GLUT to redraw the scene */
    glutPostRedisplay();
}

GLvoid
visibility( int state )
{
    if (state == GLUT_VISIBLE) {
        glutIdleFunc( animate );
    } else {
        glutIdleFunc( NULL );
    }
}

GLvoid
drawScene( GLvoid )
{
    /* clips away all but right hand wedge when enabled */
    GLdouble right[4] = { 1.0, 0.0, 0.0, -0.5 };
    /* clips away all but left hand wedge when enabled */
    GLdouble left[4]  = { -1.0, 0.0, 0.0, -0.5 };
    GLdouble bottom[4] = { 0.0, 1.0, 0.0, -0.5 };
    GLdouble top[4]  = { 0.0, -1.0, 0.0, -0.5 };

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    glPushMatrix();
        glRotatef( angle, 0.0, 1.0, 0.0 );

        /* define clipping planes fixed in scene */
        glClipPlane (GL_CLIP_PLANE0, left);
        glClipPlane (GL_CLIP_PLANE1, right);
        glClipPlane (GL_CLIP_PLANE2, top);
        glClipPlane (GL_CLIP_PLANE3, bottom);

        /* clip parts of the solid sphere */
        glEnable( GL_CLIP_PLANE0 );
            glutSolidSphere(1.5, 15, 15);
        glDisable( GL_CLIP_PLANE0 );

        glEnable( GL_CLIP_PLANE1 );
            glutSolidSphere(1.5, 15, 15);
        glDisable( GL_CLIP_PLANE1 );

        glEnable( GL_CLIP_PLANE2 );
            glutSolidSphere(1.5, 15, 15);
        glDisable( GL_CLIP_PLANE2 );

        glEnable( GL_CLIP_PLANE3 );
            glutSolidSphere(1.5, 15, 15);
        glDisable( GL_CLIP_PLANE3 );

        glutSolidSphere(0.3, 15, 15);

    glPopMatrix();

    glutSwapBuffers();
}