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/**
* @file llatmosphere.cpp
* @brief LLAtmosphere integration impl
*
* $LicenseInfo:firstyear=2018&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2018, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#include "linden_common.h"
#include "llatmosphere.h"
#include "llfasttimer.h"
#include "llsys.h"
#include "llglheaders.h"
#include "llrender.h"
#include "llshadermgr.h"
#include "llglslshader.h"
LLAtmosphere* gAtmosphere = nullptr;
void LLAtmosphere::initClass()
{
if (!gAtmosphere)
{
gAtmosphere = new LLAtmosphere;
}
}
void LLAtmosphere::cleanupClass()
{
if(gAtmosphere)
{
delete gAtmosphere;
}
gAtmosphere = NULL;
}
LLAtmosphere::LLAtmosphere()
{
// Init libatmosphere model
m_config.num_scattering_orders = 4;
// Values from "Reference Solar Spectral Irradiance: ASTM G-173", ETR column
// (see http://rredc.nrel.gov/solar/spectra/am1.5/ASTMG173/ASTMG173.html),
// summed and averaged in each bin (e.g. the value for 360nm is the average
// of the ASTM G-173 values for all wavelengths between 360 and 370nm).
// Values in W.m^-2.
const int kLambdaMin = 360;
const int kLambdaMax = 830;
const double kSolarIrradiance[48] = {
1.11776, 1.14259, 1.01249, 1.14716, 1.72765, 1.73054, 1.6887, 1.61253,
1.91198, 2.03474, 2.02042, 2.02212, 1.93377, 1.95809, 1.91686, 1.8298,
1.8685, 1.8931, 1.85149, 1.8504, 1.8341, 1.8345, 1.8147, 1.78158, 1.7533,
1.6965, 1.68194, 1.64654, 1.6048, 1.52143, 1.55622, 1.5113, 1.474, 1.4482,
1.41018, 1.36775, 1.34188, 1.31429, 1.28303, 1.26758, 1.2367, 1.2082,
1.18737, 1.14683, 1.12362, 1.1058, 1.07124, 1.04992
};
// Values from http://www.iup.uni-bremen.de/gruppen/molspec/databases/
// referencespectra/o3spectra2011/index.html for 233K, summed and averaged in
// each bin (e.g. the value for 360nm is the average of the original values
// for all wavelengths between 360 and 370nm). Values in m^2.
const double kOzoneCrossSection[48] = {
1.18e-27, 2.182e-28, 2.818e-28, 6.636e-28, 1.527e-27, 2.763e-27, 5.52e-27,
8.451e-27, 1.582e-26, 2.316e-26, 3.669e-26, 4.924e-26, 7.752e-26, 9.016e-26,
1.48e-25, 1.602e-25, 2.139e-25, 2.755e-25, 3.091e-25, 3.5e-25, 4.266e-25,
4.672e-25, 4.398e-25, 4.701e-25, 5.019e-25, 4.305e-25, 3.74e-25, 3.215e-25,
2.662e-25, 2.238e-25, 1.852e-25, 1.473e-25, 1.209e-25, 9.423e-26, 7.455e-26,
6.566e-26, 5.105e-26, 4.15e-26, 4.228e-26, 3.237e-26, 2.451e-26, 2.801e-26,
2.534e-26, 1.624e-26, 1.465e-26, 2.078e-26, 1.383e-26, 7.105e-27
};
// From https://en.wikipedia.org/wiki/Dobson_unit, in molecules.m^-2.
const double kDobsonUnit = 2.687e20;
// Maximum number density of ozone molecules, in m^-3 (computed so at to get
// 300 Dobson units of ozone - for this we divide 300 DU by the integral of
// the ozone density profile defined below, which is equal to 15km).
const double kMaxOzoneNumberDensity = 300.0 * kDobsonUnit / 15000.0;
const double kSunAngularRadius = 0.00935 / 2.0;
const double kBottomRadius = 6360000.0;
const double kTopRadius = 6420000.0;
const double kRayleigh = 1.24062e-6;
const double kRayleighScaleHeight = 8000.0;
const double kMieScaleHeight = 1200.0;
const double kMieAngstromAlpha = 0.0;
const double kMieAngstromBeta = 5.328e-3;
const double kMieSingleScatteringAlbedo = 0.9;
const double kMiePhaseFunctionG = 0.8;
const double max_sun_zenith_angle = F_PI * 2.0 / 3.0;
atmosphere::DensityProfileLayer rayleigh_density(0.0, 1.0, -1.0 / kRayleighScaleHeight, 0.0, 0.0);
atmosphere::DensityProfileLayer mie_density(0.0, 1.0, -1.0 / kMieScaleHeight, 0.0, 0.0);
// Density profile increasing linearly from 0 to 1 between 10 and 25km, and
// decreasing linearly from 1 to 0 between 25 and 40km. This is an approximate
// profile from http://www.kln.ac.lk/science/Chemistry/Teaching_Resources/
// Documents/Introduction%20to%20atmospheric%20chemistry.pdf (page 10).
std::vector<atmosphere::DensityProfileLayer> ozone_density;
ozone_density.push_back(atmosphere::DensityProfileLayer(25000.0, 0.0, 0.0, 1.0 / 15000.0, -2.0 / 3.0));
ozone_density.push_back(atmosphere::DensityProfileLayer(0.0, 0.0, 0.0, -1.0 / 15000.0, 8.0 / 3.0));
std::vector<double> wavelengths;
std::vector<double> solar_irradiance;
std::vector<double> rayleigh_scattering;
std::vector<double> mie_scattering;
std::vector<double> mie_extinction;
std::vector<double> absorption_extinction;
std::vector<double> ground_albedo;
for (int l = kLambdaMin; l <= kLambdaMax; l += 10)
{
double lambda = static_cast<double>(l) * 1e-3; // micro-meters
double mie = kMieAngstromBeta / kMieScaleHeight * pow(lambda, -kMieAngstromAlpha);
wavelengths.push_back(l);
solar_irradiance.push_back(kSolarIrradiance[(l - kLambdaMin) / 10]);
rayleigh_scattering.push_back(kRayleigh * pow(lambda, -4));
mie_scattering.push_back(mie * kMieSingleScatteringAlbedo);
mie_extinction.push_back(mie);
absorption_extinction.push_back(kMaxOzoneNumberDensity * kOzoneCrossSection[(l - kLambdaMin) / 10]);
ground_albedo.push_back(0.1f);
}
m_model = new atmosphere::Model(
wavelengths,
solar_irradiance,
kSunAngularRadius,
kBottomRadius,
kTopRadius,
{rayleigh_density},
rayleigh_scattering,
{mie_density},
mie_scattering,
mie_extinction,
kMiePhaseFunctionG,
ozone_density,
absorption_extinction,
ground_albedo,
max_sun_zenith_angle,
1000.0,
15,
false,
true);
m_model->Init(m_config, m_textures);
m_transmittance = new LLGLTexture;
m_scattering = new LLGLTexture;
m_mie_scattering = new LLGLTexture;
m_transmittance->generateGLTexture();
m_transmittance->setAddressMode(LLTexUnit::eTextureAddressMode::TAM_CLAMP);
m_transmittance->setFilteringOption(LLTexUnit::eTextureFilterOptions::TFO_BILINEAR);
m_transmittance->setExplicitFormat(GL_RGB16F_ARB, GL_RGB, GL_FLOAT);
m_transmittance->setTexName(m_textures.transmittance_texture);
m_transmittance->setTarget(GL_TEXTURE_2D, LLTexUnit::TT_TEXTURE);
m_scattering->generateGLTexture();
m_scattering->setAddressMode(LLTexUnit::eTextureAddressMode::TAM_CLAMP);
m_scattering->setFilteringOption(LLTexUnit::eTextureFilterOptions::TFO_BILINEAR);
m_scattering->setExplicitFormat(GL_RGB16F_ARB, GL_RGB, GL_FLOAT);
m_scattering->setTexName(m_textures.transmittance_texture);
m_scattering->setTarget(GL_TEXTURE_3D, LLTexUnit::TT_TEXTURE_3D);
m_mie_scattering->generateGLTexture();
m_mie_scattering->setAddressMode(LLTexUnit::eTextureAddressMode::TAM_CLAMP);
m_mie_scattering->setFilteringOption(LLTexUnit::eTextureFilterOptions::TFO_BILINEAR);
m_mie_scattering->setExplicitFormat(GL_RGB16F_ARB, GL_RGB, GL_FLOAT);
m_mie_scattering->setTexName(m_textures.transmittance_texture);
m_mie_scattering->setTarget(GL_TEXTURE_3D, LLTexUnit::TT_TEXTURE_3D);
};
LLAtmosphere::~LLAtmosphere()
{
// Cease referencing textures from atmosphere::model from our LLGLTextures wrappers for same.
m_transmittance->setTexName(0);
m_scattering->setTexName(0);
m_mie_scattering->setTexName(0);
delete m_model;
m_model = nullptr;
}
LLGLTexture* LLAtmosphere::getTransmittance() const
{
return m_transmittance;
}
LLGLTexture* LLAtmosphere::getScattering() const
{
return m_scattering;
}
LLGLTexture* LLAtmosphere::getMieScattering() const
{
return m_mie_scattering;
}
GLuint LLAtmosphere::getAtmosphericShaderForLink() const
{
return m_model ? m_model->GetShader() : 0;
}
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