/**
 * Precomputed Atmospheric Scattering
 * Copyright (c) 2008 INRIA
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * Author: Eric Bruneton
 */

const float SUN_INTENSITY = 100.0;

const vec3 earthPos = vec3(0.0, 0.0, 6360010.0);

// ----------------------------------------------------------------------------
// PHYSICAL MODEL PARAMETERS
// ----------------------------------------------------------------------------

const float SCALE = 1000.0;

const float Rg = 6360.0 * SCALE;
const float Rt = 6420.0 * SCALE;
const float RL = 6421.0 * SCALE;

const float AVERAGE_GROUND_REFLECTANCE = 0.1;

// Rayleigh
const float HR = 8.0 * SCALE;
const vec3 betaR = vec3(5.8e-3, 1.35e-2, 3.31e-2) / SCALE;

// Mie
// DEFAULT
const float HM = 1.2 * SCALE;
const vec3 betaMSca = vec3(4e-3) / SCALE;
const vec3 betaMEx = betaMSca / 0.9;
const float mieG = 0.8;
// CLEAR SKY
/*const float HM = 1.2 * SCALE;
const vec3 betaMSca = vec3(20e-3) / SCALE;
const vec3 betaMEx = betaMSca / 0.9;
const float mieG = 0.76;*/
// PARTLY CLOUDY
/*const float HM = 3.0 * SCALE;
const vec3 betaMSca = vec3(3e-3) / SCALE;
const vec3 betaMEx = betaMSca / 0.9;
const float mieG = 0.65;*/

const float g = 9.81;

const float M_PI = 3.141592657;

// ----------------------------------------------------------------------------
// NUMERICAL INTEGRATION PARAMETERS
// ----------------------------------------------------------------------------

const int TRANSMITTANCE_INTEGRAL_SAMPLES = 500;
const int INSCATTER_INTEGRAL_SAMPLES = 50;
const int IRRADIANCE_INTEGRAL_SAMPLES = 32;
const int INSCATTER_SPHERICAL_INTEGRAL_SAMPLES = 16;

// ----------------------------------------------------------------------------
// PARAMETERIZATION OPTIONS
// ----------------------------------------------------------------------------

const int TRANSMITTANCE_W = 256;
const int TRANSMITTANCE_H = 64;

const int SKY_W = 64;
const int SKY_H = 16;

const int RES_R = 32;
const int RES_MU = 128;
const int RES_MU_S = 32;
const int RES_NU = 8;

#define TRANSMITTANCE_NON_LINEAR
#define INSCATTER_NON_LINEAR