SGI Developer Toolbox 6.1/SGI Developer Toolbox 6.1 - Disc 1.iso/toolbox/src/tutorials/custEducation/opengl1/examples/adv_lighting/twoSide.c

C/C++ Source or Header | 1996-11-11 | 4.6 KB | 216 lines

/* Copyright 1993, 1996, 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 * This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;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 Unpublished -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.
 */

/* twoSide.c - demonstrates two-sided lighting model and ambient
 *        lighting; it renders a rotating cylinder which as different
 *        material properties for the front and back sides of a cylinder.
 *
 *    <l> key            - toggle LIGHT0 on / off
 *    Escape key        - exit the program
 */
#include <math.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdio.h>

/*  Function Prototypes  */

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

GLvoid  toggleLight( GLvoid );

void resetView( GLvoid );
void polarView( GLfloat, GLfloat, GLfloat, GLfloat );
void printHelp( char * );

/* Global Definitions */

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

/* Global Variables */

static GLfloat        spin = 0.0;

static GLdouble        fovy, near, far;
static GLfloat        distance, twistAngle, incAngle, azimAngle;

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

    glutInit( &argc, argv );

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

    initgfx();

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

    printHelp( argv[0] );

    glutMainLoop();
}

void
printHelp( char *progname )
{
    fprintf(stdout, "\n%s - demonstrate two sided lighting\n\n"
        "Escape key        - exit the program\n"
        "<l> key        - toggle LIGHT0 on / off\n\n",
        progname);
}

GLvoid
initgfx( GLvoid )
{
    GLfloat mat_ambient[] = { 0.25, 0.05, 0.4, 1.0 };
    GLfloat mat_diffuse[] = { 0.5, 0.1, 0.8, 1.0 };
    GLfloat mat_diffuse_back[] = { 1.0, 1.0, 0.0, 1.0 };

    GLfloat lmodel_ambient[] = { 0.8, 0.8, 0.8, 1.0 };
    GLfloat two_side = 1.0;

    glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
    glMaterialfv(GL_BACK, GL_DIFFUSE, mat_diffuse_back);

    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
    glLightModelf(GL_LIGHT_MODEL_TWO_SIDE, two_side);

    glEnable(GL_LIGHTING);
    glEnable( GL_LIGHT0 );

    glClearColor( 0.0, 0.0, 0.0, 1.0 );
    glEnable( GL_DEPTH_TEST );

    fovy = 60.0;    /* field of view in Y */
    near = 3.0;    /* Near clipping plane location */
    far  = 12.0;    /* Far clipping plane location */

    resetView();
}

void
animate()
{
    spin = fmodf(spin + 1.0, 360.0);
    glutPostRedisplay();
}

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

GLvoid
keyboard( char key, int x, int y )
{

    switch (key) {
    case 'l':
        toggleLight();
        break;
    case KEY_ESC:
        exit(0);
    }
}


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

    glViewport( 0, 0, width, height );

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    aspect = (GLdouble) width / (GLdouble) height;
    gluPerspective( fovy, aspect, near, far );
    glMatrixMode( GL_MODELVIEW );
}

GLvoid
toggleLight( GLvoid )
{
    static GLboolean lightOn = GL_TRUE;

    lightOn = !lightOn;
    if ( lightOn )
        glEnable( GL_LIGHT0 );
    else
        glDisable( GL_LIGHT0 );
}

void
resetView()
{
    distance = 8.0;
    incAngle = 30.0;
    azimAngle = 0.0;
}

void
polarView( GLfloat distance, GLfloat azimuth, GLfloat incidence,
            GLfloat twist)
{
    glTranslatef( 0.0, 0.0, -distance);
    glRotatef( -twist, 0.0, 0.0, 1.0);
    glRotatef( -incidence, 1.0, 0.0, 0.0);
    glRotatef( -azimuth, 0.0, 0.0, 1.0);
}

GLvoid
drawScene( GLvoid )
{

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    glPushMatrix();

        polarView( distance, azimAngle, incAngle, 0 );

        glPushMatrix();
            glRotatef( spin, 1.0, 1.0, 0.0 );
            SolidCylinder( 1.0, 2.0 );
        glPopMatrix();

    glPopMatrix();

    glutSwapBuffers();
}