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

C/C++ Source or Header | 1996-11-11 | 4.5 KB | 195 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 * This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;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 Unpublished -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.
 */

/*  blur.c
 *  This program demonstrates using the accumulation buffer for
 *  effects like motion blur.
 *
 *    Escape key               - exit the 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  printHelp( char * );

/* Global Definitions */

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

/* Global Variables */

static GLfloat        incAngle, azimAngle, distance;
static GLint        xStart, yStart;

static GLfloat        spin = 0.0;

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

    glutInit( &argc, argv );

    width = glutGet( GLUT_SCREEN_WIDTH );
    height = glutGet( GLUT_SCREEN_HEIGHT );
    glutInitWindowPosition( width/4, height/4 );
    glutInitWindowSize( width/4, height/4 );
    glutInitDisplayMode( GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE|GLUT_ACCUM );
    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 - motion blurring using the accumulation buffer\n\n"
        "Expect it to run very slowly on systems without \n"
        "a hardware accumulation buffer.\n\n"
        "Escape key        - exit the program\n\n",
        progname);
}

GLvoid
initgfx( void )
{
    static GLfloat mat_ambient[] = { 0.25, 0.05, 0.4, 1.0 };
    static GLfloat mat_diffuse[] = { 0.5, 0.1, 0.8, 1.0 };
    static GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
        static GLfloat mat_shininess[] = { 10.0 };

    static GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 };
    static GLfloat lmodel_ambient[] = { 0.2, 0.2, 0.2, 1.0 };

    glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
    glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);

    glLightfv(GL_LIGHT0, GL_POSITION, light_position);
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);

    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);

    glClearColor( 0.0, 0.0, 0.0, 1.0 );

    glClearAccum( 0.0, 0.0, 0.0, 0.0 );
    glClear( GL_ACCUM_BUFFER_BIT );

    glEnable( GL_DEPTH_TEST );
    glEnable( GL_CULL_FACE );

    distance = 4.5;
    incAngle = 25.0;
    azimAngle = 0.0;
}

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, 7.0 );
    glMatrixMode( GL_MODELVIEW );

    glClear( GL_ACCUM_BUFFER_BIT );
}

GLvoid
animate( GLvoid )
{
    spin = fmodf( spin + 10.0, 360.0 );    /* update spin */
    glutPostRedisplay();            /* Tell GLUT to redraw */
}

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

GLvoid
drawScene( GLvoid )
{
    static GLfloat decayFactor = 0.5;

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    glPushMatrix();

        glTranslatef( 0.0, 0.0, -distance);
        glRotatef( incAngle, 1.0, 0.0, 0.0 );
        glRotatef( azimAngle, 0.0, 0.0, 1.0 );

        glPushMatrix();
            glAccum( GL_MULT, decayFactor );
            glRotatef( spin, 0.0, 1.0, 0.0 );
            glTranslatef( 1.0, 0.0, 0.0 );
            glutSolidSphere( 0.5, 15, 15 );
            glAccum( GL_ACCUM, (1.0-decayFactor) );
            glAccum( GL_RETURN, 1.0 );
        glPopMatrix();

    glPopMatrix();

    glutSwapBuffers();
}