/*
 * MainAntiAlias - demonstration of full-screen anti-aliasing. Derived from 
 * accpersp.c example from the Red Book, but simplified to only deal with
 * anti-aliasing. Silicon Graphics original copyright statement below.
 * 
 * (c) Copyright 1993, 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 * Unpublished-- rights reserved under the copyright laws of the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(TM) is a trademark of Silicon Graphics, Inc.
 */

#include <GL/glut.h>
#include <stdlib.h>
#include <math.h>
#include "jitter.h"

#ifdef WIN32
#define near zNear
#define far zFar
#endif

#define PI_ 3.14159265358979323846

int doAntialias=1;

/* jitteredFrustum()
 * The first 6 arguments are identical to the glFrustum() call. 
 * pixdx and pixdy are anti-alias jitter in pixels. 
 */

void jitteredFrustum(GLdouble left, GLdouble right, GLdouble bottom, 
   GLdouble top, GLdouble near, GLdouble far, GLdouble pixdx, 
   GLdouble pixdy) {

   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]);
   dy = -(pixdy*ywsize/(GLdouble) viewport[3]);
	
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glFrustum (left + dx, right + dx, bottom + dy, top + dy, near, far);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

/* jitteredPerspective()
 * 
 * The first 4 arguments are identical to the gluPerspective() call.
 * pixdx and pixdy are anti-alias jitter in pixels. 
 */

void jitteredPerspective(GLdouble fovy, GLdouble aspect, 
   GLdouble near, GLdouble far, GLdouble pixdx, GLdouble pixdy) {

	GLdouble fov2,left,right,bottom,top;

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

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

   right = top * aspect;
   left = -right;

   jitteredFrustum (left, right, bottom, top, near, far,
               pixdx, pixdy);
}

/*  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 teapot1_diffuse[] = { 0.7, 0.7, 0.0, 1.0 };
   GLfloat teapot2_diffuse[] = { 0.0, 0.7, 0.7, 1.0 };
   GLfloat teapot3_diffuse[] = { 0.7, 0.0, 0.7, 1.0 };
    
   glPushMatrix ();
   glTranslatef (0.0, 0.0, -5.0); 

   glPushMatrix ();
   glTranslatef (-0.80, 0.35, 0.0); 
   glRotatef (90.0, 1.0, 0.0, 0.0);
   glMaterialfv(GL_FRONT, GL_DIFFUSE, teapot1_diffuse);
   glutSolidTeapot(1.0);
   glPopMatrix ();

   glPushMatrix ();
   glTranslatef (0.0, -0.50, 0.0); 
   glRotatef (270.0, 0.0, 0.0, 1.0);
   glMaterialfv(GL_FRONT, GL_DIFFUSE, teapot2_diffuse);
   glutSolidTeapot(1.0);
   glPopMatrix ();

   glPushMatrix ();
   glTranslatef (0.75, 0.60, 0.0); 
   glMaterialfv(GL_FRONT, GL_DIFFUSE, teapot3_diffuse);
   glutSolidTeapot(1.0);
   glPopMatrix ();

   glPopMatrix ();
}

#define ACSIZE	8

void display(void)
{
	GLint viewport[4];
	int jitter;
	
	glGetIntegerv (GL_VIEWPORT, viewport);
	
	if (doAntialias) {	
		glClear(GL_ACCUM_BUFFER_BIT);
		for (jitter = 0; jitter < ACSIZE; jitter++) {
			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
			jitteredPerspective (50.0, 
				(GLdouble) viewport[2]/(GLdouble) viewport[3], 
				1.0, 15.0, j8[jitter].x, j8[jitter].y);
			displayObjects ();
			glAccum(GL_ACCUM, 1.0/ACSIZE);
		}
		glAccum (GL_RETURN, 1.0);
	}
	else {
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		gluPerspective(50.0, 
			(GLdouble) viewport[2]/(GLdouble) viewport[3], 
			1.0, 15.0);
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
		displayObjects ();
	}
	glFlush();
	glutSwapBuffers();
}

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

void keyboard(unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
         exit(0);
         break;
	  case 'a':
		  doAntialias = 1 - doAntialias;
		  break;
   }
  glutPostRedisplay();
}

void menu(int item)
{

  switch (item) {

  case 1:
		  doAntialias = 1 - doAntialias;
		  break;
  }
  glutPostRedisplay();
}


/*  
 *  Main Loop
 *  Be certain you request an accumulation buffer.
 */

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB
                        | GLUT_ACCUM | GLUT_DEPTH);
   glutInitWindowSize (200, 200);
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init();
   glutReshapeFunc(reshape);
   glutDisplayFunc(display);
   glutKeyboardFunc(keyboard);
   glutCreateMenu(menu);
   glutAddMenuEntry("Toggle full screen anti-aliasing", 1);
   glutAttachMenu(GLUT_RIGHT_BUTTON);
   glutMainLoop();
   return 0;
}