/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 *               1993-1995 Microsoft Corporation
 *
 * ALL RIGHTS RESERVED
 *
 * Please refer to OpenGL/readme.txt for additional information
 *
 */

/*
 *  dof.c
 *  This program demonstrates use of the accumulation buffer to
 *  create an out-of-focus depth-of-field effect.  The teapots
 *  are drawn several times into the accumulation buffer.  The
 *  viewing volume is jittered, except at the focal point, where
 *  the viewing volume is at the same position, each time.  In
 *  this case, the gold teapot remains in focus.
 */
#include "glos.h"

#include <GL/gl.h>
#include <GL/glu.h>
#include <math.h>
#include <GL/glaux.h>
#include "jitter.h"

void myinit(void);
void accFrustum(GLdouble left, GLdouble right, GLdouble bottom,
    GLdouble top, GLdouble znear, GLdouble zfar, GLdouble pixdx, 
    GLdouble pixdy, GLdouble eyedx, GLdouble eyedy, GLdouble focus);
void accPerspective(GLdouble fovy, GLdouble aspect,
    GLdouble znear, GLdouble zfar, GLdouble pixdx, GLdouble pixdy, 
    GLdouble eyedx, GLdouble eyedy, GLdouble focus);
void renderTeapot (GLfloat x, GLfloat y, GLfloat z,
    GLfloat ambr, GLfloat ambg, GLfloat ambb, 
    GLfloat difr, GLfloat difg, GLfloat difb, 
    GLfloat specr, GLfloat specg, GLfloat specb, GLfloat shine);
void CALLBACK myReshape(GLsizei w, GLsizei h);
void CALLBACK display(void);

#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 znear, GLdouble zfar, 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*znear/focus);
    dy = -(pixdy*ywsize/(GLdouble) viewport[3] + eyedy*znear/focus);
    
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glFrustum (left + dx, right + dx, bottom + dy, top + dy, znear, zfar);
    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 znear, GLdouble zfar, GLdouble pixdx, GLdouble pixdy, 
    GLdouble eyedx, GLdouble eyedy, GLdouble focus)
{
    GLdouble fov2,left,right,bottom,top;

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

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

    right = top * aspect;
    left = -right;

    accFrustum (left, right, bottom, top, znear, zfar,
    pixdx, pixdy, eyedx, eyedy, focus);
}

void myinit(void)
{
    GLfloat ambient[] = { 0.0, 0.0, 0.0, 1.0 };
    GLfloat diffuse[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat specular[] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat position[] = { 0.0, 3.0, 3.0, 0.0 };
    
    GLfloat lmodel_ambient[] = { 0.2, 0.2, 0.2, 1.0 };
    GLfloat local_view[] = { 0.0 };

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);

    glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
    glLightfv(GL_LIGHT0, GL_POSITION, position);
    
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
    glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);

    glFrontFace (GL_CW);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glEnable(GL_AUTO_NORMAL);
    glEnable(GL_NORMALIZE);

    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();

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

void renderTeapot (GLfloat x, GLfloat y, GLfloat z, 
    GLfloat ambr, GLfloat ambg, GLfloat ambb, 
    GLfloat difr, GLfloat difg, GLfloat difb, 
    GLfloat specr, GLfloat specg, GLfloat specb, GLfloat shine)
{
    float mat[3];

    glPushMatrix();
    glTranslatef (x, y, z);
    mat[0] = ambr; mat[1] = ambg; mat[2] = ambb;    
    glMaterialfv (GL_FRONT, GL_AMBIENT, mat);
    mat[0] = difr; mat[1] = difg; mat[2] = difb;    
    glMaterialfv (GL_FRONT, GL_DIFFUSE, mat);
    mat[0] = specr; mat[1] = specg; mat[2] = specb;
    glMaterialfv (GL_FRONT, GL_SPECULAR, mat);
    glMaterialf (GL_FRONT, GL_SHININESS, shine*128.0);
    auxSolidTeapot(0.5);
    glPopMatrix();
}

/*  display() draws 5 teapots into the accumulation buffer 
 *  several times; each time with a jittered perspective.
 *  The focal point is at z = 5.0, so the gold teapot will 
 *  stay in focus.  The amount of jitter is adjusted by the
 *  magnitude of the accPerspective() jitter; in this example, 0.33.
 *  In this example, the teapots are drawn 8 times.  See jitter.h
 */
void CALLBACK display(void)
{
    int jitter;
    GLint viewport[4];

    glGetIntegerv (GL_VIEWPORT, viewport);
    glClear(GL_ACCUM_BUFFER_BIT);

    for (jitter = 0; jitter < 8; jitter++) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    accPerspective (45.0, 
        (GLdouble) viewport[2]/(GLdouble) viewport[3], 
        1.0, 15.0, 0.0, 0.0,
        0.33*j8[jitter].x, 0.33*j8[jitter].y, 5.0);
/*  ruby, gold, silver, emerald, and cyan teapots   */
    renderTeapot (-1.1, -0.5, -4.5, 0.1745, 0.01175, 0.01175,
        0.61424, 0.04136, 0.04136, 0.727811, 0.626959, 0.626959, 0.6);
    renderTeapot (-0.5, -0.5, -5.0, 0.24725, 0.1995, 0.0745,
        0.75164, 0.60648, 0.22648, 0.628281, 0.555802, 0.366065, 0.4);
    renderTeapot (0.2, -0.5, -5.5, 0.19225, 0.19225, 0.19225,
        0.50754, 0.50754, 0.50754, 0.508273, 0.508273, 0.508273, 0.4);
    renderTeapot (1.0, -0.5, -6.0, 0.0215, 0.1745, 0.0215, 
        0.07568, 0.61424, 0.07568, 0.633, 0.727811, 0.633, 0.6);
    renderTeapot (1.8, -0.5, -6.5, 0.0, 0.1, 0.06, 0.0, 0.50980392, 
        0.50980392, 0.50196078, 0.50196078, 0.50196078, .25);
    glAccum (GL_ACCUM, 0.125);
    }

    glAccum (GL_RETURN, 1.0);
    glFlush();
}

void CALLBACK myReshape(GLsizei w, GLsizei h)
{
    h = (h == 0) ? 1 : h;
    glViewport(0, 0, w, h);
}

/*  Main Loop
 *  Open window with initial window size, title bar, 
 *  RGBA display mode, depth buffer, and handle input events.
 */
int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB
            | AUX_ACCUM | AUX_DEPTH16);
    auxInitPosition (0, 0, 400, 400);
    auxInitWindow ("Depth-of-Field");
    myinit();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
    return(0);
}
