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

C/C++ Source or Header | 1996-11-11 | 4.5 KB | 192 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 * This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;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 Unpublished -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.
 */

/* lookat.c - use input from the keyboard to control the viewpoint
 *
 *    F1 key        - print help information
 *    Left Arrow Key    - move the reference point to the left
 *    Right Arrow Key    - move the reference point to the right
 *    Up Arrow Key    - move the reference point up
 *    Down Arrow Key    - move the reference point down
 *    Escape key     - exit the program
 */

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <math.h>
#include <stdio.h>    /* for printf */

/*  Function Prototypes  */

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

void printHelp( char * );

/* Global Definitions */

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

/* Global Variables */

static GLdouble        xRef = 0.0, yRef = 0.0;

static char *progname;

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

    glutInit( &argc, argv );

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

    initgfx();

    glutKeyboardFunc( keyboard );
    glutSpecialFunc( specialkeys );
    glutReshapeFunc( reshape );
    glutDisplayFunc( drawScene );

    progname = argv[0];
    printHelp( progname );

    glutMainLoop();
}

void
printHelp( char *progname )
{
    fprintf(stdout, "\n%s - uses keyboard input to control the "
        "location of the reference point point\n\n"
        "F1 Key            - print Help information\n"
        "Left Arrow Key        - move reference point to the left\n"
        "Right Arrow Key    - move reference point to the right\n"
        "Up Arrow Key        - move reference point up\n"
        "Down Arrow Key        - move reference point down\n"
        "Escape Key        - exit the program\n\n",
        progname);
}

GLvoid
initgfx( GLvoid )
{
    glClearColor( 0.0, 0.0, 0.0, 1.0 );
    glShadeModel( GL_FLAT );
    glEnable( GL_DEPTH_TEST );
}

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, 1.0, 20.0 );
    glMatrixMode( GL_MODELVIEW );
}

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

GLvoid
specialkeys( GLint key, GLint x, GLint y )
{
    switch (key) {
    case GLUT_KEY_F1:    /* print Help */
        printHelp( progname );
        break;

    case GLUT_KEY_LEFT:    /* move reference point to the left */
        xRef -= 0.5;
        if (xRef < -4.0) xRef = -4.0;
        glutPostRedisplay();
         break;

    case GLUT_KEY_RIGHT:    /* move reference point to the right */
        xRef += 0.5;
        if (xRef > 4.0) xRef = 4.0;
        glutPostRedisplay();
        break;

    case GLUT_KEY_UP:    /* move reference point up */
        yRef += 0.5;
        if (yRef > 3.0) yRef = 3.0;
        glutPostRedisplay();
        break;

    case GLUT_KEY_DOWN:    /* move reference point down */
        yRef -= 0.5;
        if (yRef < -3.0) yRef = -3.0;
        glutPostRedisplay();
        break;
    }
}

GLvoid
drawScene( GLvoid )
{
    static GLfloat    upperArmColor[] = { 1.0, 0.0, 0.0 };
    static GLfloat    lowerArmColor[] = { 0.8, 0.5, 0.5 };

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    glPushMatrix();

        /* Move the reference point */
        gluLookAt( 0.0, 0.0, 8.0, xRef, yRef, 0.0, 0.0, 1.0, 0.0 );

        XYaxes();

        /* Draw the shoulder at the new origin */
        glTranslatef( 1.0, 0.0, 0.0 );
            glColor3fv( upperArmColor );
        WireBox( 2.0, 0.4, 1.0 );

        /* Draw the lower arm at the end of the upper arm and
          * rotate it 45 degrees */
        glTranslatef( 1.0, 0.0, 0.0 );
        glRotatef( 45.0, 0.0, 0.0, 1.0 );
        glTranslatef( 1.0, 0.0, 0.0 );
            glColor3fv( lowerArmColor );
        WireBox( 2.0, 0.4, 1.0 );
    glPopMatrix();

    glutSwapBuffers();
}