/*
 * License Applicability. Except to the extent portions of this file are
 * made subject to an alternative license as permitted in the SGI Free
 * Software License B, Version 1.1 (the "License"), the contents of this
 * file are subject only to the provisions of the License. You may not use
 * this file except in compliance with the License. You may obtain a copy
 * of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
 * Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
 * 
 * http://oss.sgi.com/projects/FreeB
 * 
 * Note that, as provided in the License, the Software is distributed on an
 * "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
 * DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
 * CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
 * PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
 * 
 * Original Code. The Original Code is: OpenGL Sample Implementation,
 * Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
 * Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
 * Copyright in any portions created by third parties is as indicated
 * elsewhere herein. All Rights Reserved.
 * 
 * Additional Notice Provisions: The application programming interfaces
 * established by SGI in conjunction with the Original Code are The
 * OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
 * April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
 * 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
 * Window System(R) (Version 1.3), released October 19, 1998. This software
 * was created using the OpenGL(R) version 1.2.1 Sample Implementation
 * published by SGI, but has not been independently verified as being
 * compliant with the OpenGL(R) version 1.2.1 Specification.
 *
 */

/*
 *  fog.c
 *  This program draws 5 red spheres, each at a different 
 *  z distance from the eye, in different types of fog.  
 *  Pressing the f key chooses between 3 types of 
 *  fog:  exponential, exponential squared, and linear.  
 *  In this program, there is a fixed density value, as well 
 *  as fixed start and end values for the linear fog.
 */
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include "ug.h"

static GLint fogMode;

/*  Initialize depth buffer, fog, light source, 
 *  material property, and lighting model.
 */
static void init(void)
{
   GLfloat position[] = { 0.5, 0.5, 3.0, 0.0 };

   glEnable(GL_DEPTH_TEST);

   glLightfv(GL_LIGHT0, GL_POSITION, position);
   glEnable(GL_LIGHTING);
   glEnable(GL_LIGHT0);
   {
      GLfloat mat[3] = {0.1745, 0.01175, 0.01175};	
      glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, mat);
      mat[0] = 0.61424; mat[1] = 0.04136; mat[2] = 0.04136;	
      glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, mat);
      mat[0] = 0.727811; mat[1] = 0.626959; mat[2] = 0.626959;
      glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, mat);
      glMaterialf (GL_FRONT_AND_BACK, GL_SHININESS, 0.6*128.0);
   }

   glEnable(GL_FOG);
   {
      GLfloat fogColor[4] = {0.5, 0.5, 0.5, 1.0};

      fogMode = GL_EXP;
      glFogx (GL_FOG_MODE, fogMode);
      glFogfv (GL_FOG_COLOR, fogColor);
      glFogf (GL_FOG_DENSITY, 0.35);
      glHint (GL_FOG_HINT, GL_DONT_CARE);
      glFogf (GL_FOG_START, 1.0);
      glFogf (GL_FOG_END, 5.0);
   }
   glClearColor(0.5, 0.5, 0.5, 1.0);  /* fog color */
}

static void renderSphere (GLfloat x, GLfloat y, GLfloat z)
{
   glPushMatrix();
   glTranslatef (x, y, z);
   ugSolidSpheref(0.4, 32, 32);
   glPopMatrix();
}

/* display() draws 5 spheres at different z positions.
 */
static void display(UGWindow uwin)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   renderSphere (-2., -0.5, -1.0);
   renderSphere (-1., -0.5, -2.0);
   renderSphere (0., -0.5, -3.0);
   renderSphere (1., -0.5, -4.0);
   renderSphere (2., -0.5, -5.0);
   glFlush();
   ugSwapBuffers(uwin);
}

static void reshape(UGWindow uwin, int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   if (w <= h)
      glOrthof(-2.5, 2.5, -2.5*(GLfloat)h/(GLfloat)w,
         2.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
   else
      glOrthof(-2.5*(GLfloat)w/(GLfloat)h,
         2.5*(GLfloat)w/(GLfloat)h, -2.5, 2.5, -10.0, 10.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity ();
}

static void keyboard(UGWindow uwin, int key, int x, int y)
{
   switch (key) {
      case 'f':
      case 'F':
         if (fogMode == GL_EXP) {
	    fogMode = GL_EXP2;
	    printf ("Fog mode is GL_EXP2\n");
         }
         else if (fogMode == GL_EXP2) {
            fogMode = GL_LINEAR;
            printf ("Fog mode is GL_LINEAR\n");
         }
         else if (fogMode == GL_LINEAR) {
            fogMode = GL_EXP;
            printf ("Fog mode is GL_EXP\n");
         }
         glFogx(GL_FOG_MODE, fogMode);
         ugPostRedisplay(uwin);
         break;
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}


/*  Main Loop
 *  Open window with initial window size, title bar, 
 *  RGBA display mode, depth buffer, and handle input events.
 */
#ifdef FTK_AS_PLUGIN
#include "ftk_app_demo.h"
FTK_HIDE int FTK_MAIN(int argc, char* argv[]);
FtkApp* ftk_app_demo_fog_create()
{
	return ftk_app_demo_create(_("fog"), ftk_main);
}
#else
#define FTK_HIDE extern
#endif /*FTK_AS_PLUGIN*/

FTK_HIDE int FTK_MAIN(int argc, char* argv[])
{
   UGCtx ug = ugInit();
   UGWindow uwin = ugCreateWindow (ug, "UG_DEPTH", "fog", 500, 500, 100, 100);
   init();
   ugDisplayFunc(uwin, display); 
   ugReshapeFunc(uwin, reshape);
   ugKeyboardFunc(uwin, keyboard);
#ifndef FTK_AS_PLUGIN
   ugMainLoop(ug);
#endif
   return 0;
}