OpenGLUT 0.6.3 development - OpenGLUT: accpersp.c File Reference
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# accpersp.c File Reference

## Detailed Description

Use the accumulation buffer to do full-scene antialiasing on a scene with perspective projection, using the special routines accFrustum() and accPerspective().

    /*
     * Copyright (c) 1993-1997, 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     * Unpublished-- rights reserved under the copyright laws of the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(R) is a registered trademark of Silicon Graphics, Inc.
     */

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

    #include "jitter.h"

    #define PI_ 3.14159265358979323846

    /* accFrustum()
     * The first 6 arguments are identical to the glFrustum() call.
     *
     * pixdx and pixdy are anti-alias jitter in pixels.
     * Set both equal to 0.0 for no anti-alias jitter.
     * eyedx and eyedy are depth-of field jitter in pixels.
     * Set both equal to 0.0 for no depth of field effects.
     *
     * focus is distance from eye to plane in focus.
     * focus must be greater than, but not equal to 0.0.
     *
     * Note that accFrustum() calls glTranslatef().  You will
     * probably want to insure that your ModelView matrix has been
     * initialized to identity before calling accFrustum().
     */
    void accFrustum(GLdouble left, GLdouble right, GLdouble bottom,
       GLdouble top, GLdouble nnear, GLdouble ffar, GLdouble pixdx,
       GLdouble pixdy, GLdouble eyedx, GLdouble eyedy, GLdouble focus)
    {
       GLdouble xwsize, ywsize;
       GLdouble dx, dy;
       GLint viewport[4];

       glGetIntegerv (GL_VIEWPORT, viewport);

       xwsize = right - left;
       ywsize = top - bottom;

       dx = -(pixdx*xwsize/(GLdouble) viewport[2] + eyedx*nnear/focus);
       dy = -(pixdy*ywsize/(GLdouble) viewport[3] + eyedy*nnear/focus);

       glMatrixMode(GL_PROJECTION);
       glLoadIdentity();
       glFrustum (left + dx, right + dx, bottom + dy, top + dy, nnear, ffar);
       glMatrixMode(GL_MODELVIEW);
       glLoadIdentity();
       glTranslatef (-eyedx, -eyedy, 0.0);
    }

    /* accPerspective()
     *
     * The first 4 arguments are identical to the gluPerspective() call.
     * pixdx and pixdy are anti-alias jitter in pixels.
     * Set both equal to 0.0 for no anti-alias jitter.
     * eyedx and eyedy are depth-of field jitter in pixels.
     * Set both equal to 0.0 for no depth of field effects.
     *
     * focus is distance from eye to plane in focus.
     * focus must be greater than, but not equal to 0.0.
     *
     * Note that accPerspective() calls accFrustum().
     */
    void accPerspective(GLdouble fovy, GLdouble aspect,
       GLdouble nnear, GLdouble ffar, GLdouble pixdx, GLdouble pixdy,
       GLdouble eyedx, GLdouble eyedy, GLdouble focus)
    {
       GLdouble fov2,left,right,bottom,top;

       fov2 = ((fovy*PI_) / 180.0) / 2.0;

       top = nnear / (cos(fov2) / sin(fov2));
       bottom = -top;

       right = top * aspect;
       left = -right;

       accFrustum (left, right, bottom, top, nnear, ffar,
                   pixdx, pixdy, eyedx, eyedy, focus);
    }

    /*  Initialize lighting and other values.
     */
    void init(void)
    {
       GLfloat mat_ambient[] = { 1.0, 1.0, 1.0, 1.0 };
       GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
       GLfloat light_position[] = { 0.0, 0.0, 10.0, 1.0 };
       GLfloat lm_ambient[] = { 0.2, 0.2, 0.2, 1.0 };

       glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
       glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
       glMaterialf(GL_FRONT, GL_SHININESS, 50.0);
       glLightfv(GL_LIGHT0, GL_POSITION, light_position);
       glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lm_ambient);

       glEnable(GL_LIGHTING);
       glEnable(GL_LIGHT0);
       glEnable(GL_DEPTH_TEST);
       glShadeModel (GL_FLAT);

       glClearColor(0.0, 0.0, 0.0, 0.0);
       glClearAccum(0.0, 0.0, 0.0, 0.0);
    }

    void displayObjects(void)
    {
       GLfloat torus_diffuse[] = { 0.7, 0.7, 0.0, 1.0 };
       GLfloat cube_diffuse[] = { 0.0, 0.7, 0.7, 1.0 };
       GLfloat sphere_diffuse[] = { 0.7, 0.0, 0.7, 1.0 };
       GLfloat octa_diffuse[] = { 0.7, 0.4, 0.4, 1.0 };

       glPushMatrix ();
       glTranslatef (0.0, 0.0, -5.0);
       glRotatef (30.0, 1.0, 0.0, 0.0);

       glPushMatrix ();
       glTranslatef (-0.80, 0.35, 0.0);
       glRotatef (100.0, 1.0, 0.0, 0.0);
       glMaterialfv(GL_FRONT, GL_DIFFUSE, torus_diffuse);
       glutSolidTorus (0.275, 0.85, 16, 16);
       glPopMatrix ();

       glPushMatrix ();
       glTranslatef (-0.75, -0.50, 0.0);
       glRotatef (45.0, 0.0, 0.0, 1.0);
       glRotatef (45.0, 1.0, 0.0, 0.0);
       glMaterialfv(GL_FRONT, GL_DIFFUSE, cube_diffuse);
       glutSolidCube (1.5);
       glPopMatrix ();

       glPushMatrix ();
       glTranslatef (0.75, 0.60, 0.0);
       glRotatef (30.0, 1.0, 0.0, 0.0);
       glMaterialfv(GL_FRONT, GL_DIFFUSE, sphere_diffuse);
       glutSolidSphere (1.0, 16, 16);
       glPopMatrix ();

       glPushMatrix ();
       glTranslatef (0.70, -0.90, 0.25);
       glMaterialfv(GL_FRONT, GL_DIFFUSE, octa_diffuse);
       glutSolidOctahedron ();
       glPopMatrix ();

       glPopMatrix ();
    }

    #define ACSIZE  8

    void display(void)
    {
       GLint viewport[4];
       int jitter;

       glGetIntegerv (GL_VIEWPORT, viewport);

       glClear(GL_ACCUM_BUFFER_BIT);
       for (jitter = 0; jitter < ACSIZE; jitter++) {
          glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
          accPerspective (50.0,
             (GLdouble) viewport[2]/(GLdouble) viewport[3],
             1.0, 15.0, j8[jitter].x, j8[jitter].y, 0.0, 0.0, 1.0);
          displayObjects ();
          glAccum(GL_ACCUM, 1.0/ACSIZE);
       }
       glAccum (GL_RETURN, 1.0);
       glFlush();
    }

    void reshape(int w, int h)
    {
       glViewport(0, 0, (GLsizei) w, (GLsizei) h);
    }

    /* ARGSUSED1 */
    void keyboard(unsigned char key, int x, int y)
    {
       switch (key) {
          case 27:
             exit(0);
             break;
       }
    }

    /*  Main Loop
     *  Be certain you request an accumulation buffer.
     */
    int main(int argc, char** argv)
    {
       glutInit(&argc, argv);
       glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB
                            | GLUT_ACCUM | GLUT_DEPTH);
       glutInitWindowSize (250, 250);
       glutInitWindowPosition (100, 100);
       glutCreateWindow (argv[0]);
       init();
       glutReshapeFunc(reshape);
       glutDisplayFunc(display);
       glutKeyboardFunc(keyboard);
       glutMainLoop();
       return 0;
    }

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