/*---------------------------------------------------------------------------*
  Project:  Horizon
  File:     Util.cpp

  Copyright (C)2009-2012 Nintendo Co., Ltd.  All rights reserved.

  These coded instructions, statements, and computer programs contain
  proprietary information of Nintendo of America Inc. and/or Nintendo
  Company Ltd., and are protected by Federal copyright law.  They may
  not be disclosed to third parties or copied or duplicated in any form,
  in whole or in part, without the prior written consent of Nintendo.

  $Rev: 46365 $
 *---------------------------------------------------------------------------*/

/*
 *------------------------------------------------------------
 * Copyright(c) 2009-2010 by Digital Media Professionals Inc.
 * All rights reserved.
 *------------------------------------------------------------
 * This source code is the confidential and proprietary
 * of Digital Media Professionals Inc.
 *------------------------------------------------------------
 */
 
#include <math.h>

#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
#include "Util.h"
#include "Tga.h"
#include "Memory.h"

void loadTexture(const char * _name, unsigned _target, int _level, bool& _useAlpha, bool _is2D, int *_width, unsigned _forceformat)
{
    unsigned char* pixels;
    unsigned width, height, format, type, orientation;
    
    (void)_useAlpha;
    pixels = (unsigned char*)dmpLoadTGA(_name, &width, &height, &format, &type, &orientation);
    if (!pixels)
        return;
    
    switch (format)
    {
        case IMAGE_RGB:     format = GL_RGB;    break;
        case IMAGE_RGBA:    format = GL_RGBA;   break;
        default:
            if (pixels)
                free(pixels);
            return;
    }
    
    /* force to convert format */
    if (_forceformat != 0 && format != _forceformat)
    {
        unsigned i;
        unsigned char* newpixels = 0;
        
        switch (format)
        {
            case GL_RGB:
                switch (_forceformat)
                {
                    case GL_RGBA:
                        newpixels = (unsigned char*)malloc(width * height * 4);
                        if (!newpixels)
                        {
                            free(pixels);
                            return;
                        }
                        for (i = 0; i < width * height; i++)
                        {
                            newpixels[i * 4 + 0] = pixels[i * 3 + 0];
                            newpixels[i * 4 + 1] = pixels[i * 3 + 1];
                            newpixels[i * 4 + 2] = pixels[i * 3 + 2];
                            newpixels[i * 4 + 3] = 0xff;
                        }
                        break;
                }
                break;
            case GL_RGBA:
                switch (_forceformat)
                {
                    case GL_RGB:
                        newpixels = (unsigned char*)malloc(width * height * 3);
                        if (!newpixels)
                        {
                            free(pixels);
                            return;
                        }
                        for (i = 0; i < width * height; i++)
                        {
                            newpixels[i * 3 + 0] = pixels[i * 4 + 0];
                            newpixels[i * 3 + 1] = pixels[i * 4 + 1];
                            newpixels[i * 3 + 2] = pixels[i * 4 + 2];
                        }
                        break;
                }
                break;
        }
        
        if (newpixels)
        {
            format = _forceformat;
            free(pixels);
            pixels = newpixels;
        }
    }
    
    switch (type)
    {
        case IMAGE_UNSIGNED_BYTE:   type = GL_UNSIGNED_BYTE;    break;
        default:
            if (pixels)
                free(pixels);
            return;
    }
    
    if (_is2D)
        glTexImage2D(_target, _level, format, width, height, 0, format, type, pixels);
    else
        glTexImage1D(_target, _level, format, width, 0, format, type, pixels);
    
    if (pixels)
        free(pixels);
    
    if (_width)
        (*_width) = width;
}

float z_schlick(float r, float t, bool normalize)
{
    float ret ;
    ret = 1.f + (r - 1.f) * t * t ;
    ret *= ret ;
    if (!ret)
        return 1000.f ;
    if (normalize)
        ret = r * r / ret ;
    else
        ret = r / ret ;
    return ret ;
}

float a_schlick(float p, float w, bool normalize)
{
    float ret ;
    w *= w ;
    ret = p * p * (1.f - w) + w ;
    if (!ret)
        return 1000.f ;
    if (normalize)
        ret = p * sqrt(1.f / ret) ;
    else
        ret = sqrt(p / ret) ;
    return ret ;
}

float gaussian(float _c, float m)
{
    GLfloat a = acos(_c) ;
    return exp( - (a * a) / (m * m)) ;
}

float beckmann(float _c, float m)
{
    float tan2 ;
    if (!_c)
        return 0.f ;
    tan2 = (_c * _c - 1.f) / (_c * _c) ;
    return exp(tan2 / (m * m)) ;
}

float beckmann2(float _c, float m)
{
    if (!_c)
        return 0.f ;
    GLfloat tan2 ;
    GLfloat cos2 = _c * _c;
    tan2 = (cos2 - 1.f) / cos2 ;
    return exp(tan2 / (m * m)) / (cos2 * cos2) ;
}

float r_fresnel(float _c, float _m, float _r0, float _r1 )
{
    // we get Schlick's approximation of the Fresnel formula
    return _r1 + (_r0 - _r1) * pow(1.f - _c, _m) ;
}

float nk_fresnel(float _c, float _n, float _k)
{
    // we get Schlick's approximation of the Fresnel formula
    GLfloat r1, r0, m ;
    r1 = ((_n-1) * (_n-1) + _k * _k) / ((_n+1)*(_n+1) + _k*_k) ;
    r0 = 1.f ;
    m  = 5.0f ;
    return r_fresnel(_c, m, r0, r1) ;
}