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Integrate skylight model. Work in progress.
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castano committed May 22, 2012
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376 changes: 376 additions & 0 deletions extern/skylight/ArHosekSkyModel.c
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/*
This source is published under the following 3-clause BSD license.
Copyright (c) 2012, Lukas Hosek and Alexander Wilkie
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* 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.
* None of the names of the 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 HOLDERS 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.
*/

/* ============================================================================
This file is part of a sample implementation of the analytical skylight model
presented in the SIGGRAPH 2012 paper
"An Analytic Model for Full Spectral Sky-Dome Radiance"
by
Lukas Hosek and Alexander Wilkie
Charles University in Prague, Czech Republic
Version: 1.0, May 11th, 2012
Please visit http://cgg.mff.cuni.cz/projects/SkylightModelling/ to check if
an updated version of this code has been published!
============================================================================ */

/*
All instructions on how to use this code are to be found in the accompanying
header file.
*/

#include "ArHosekSkyModel.h"
#include "ArHosekSkyModelData.h"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

// Some macro definitions that occur elsewhere in ART, and that have to be
// replicated to make this a stand-alone module.

#ifndef NIL
#define NIL 0
#endif

#ifndef MATH_PI
#define MATH_PI 3.141593
#endif

#ifndef ALLOC
#define ALLOC(_struct) ((_struct *)malloc(sizeof(_struct)))
#endif

// internal definitions

typedef double *ArHosekSkyModel_Dataset;
typedef double *ArHosekSkyModel_Radiance_Dataset;

// internal functions

void ArHosekSkyModel_CookConfiguration(
ArHosekSkyModel_Dataset dataset,
ArHosekSkyModelConfiguration config,
double turbidity,
double albedo,
double solar_elevation
)
{
double * elev_matrix;

int int_turbidity = turbidity;
double turbidity_rem = turbidity - (double)int_turbidity;

solar_elevation = pow(solar_elevation / (MATH_PI / 2.0), (1.0 / 3.0));

// alb 0 low turb

elev_matrix = dataset + ( 9 * 6 * (int_turbidity-1) );


for( unsigned int i = 0; i < 9; ++i )
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] =
(1.0-albedo) * (1.0 - turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}

// alb 1 low turb
elev_matrix = dataset + (9*6*10 + 9*6*(int_turbidity-1));
for(unsigned int i = 0; i < 9; ++i)
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] +=
(albedo) * (1.0 - turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}

if(int_turbidity == 10)
return;

// alb 0 high turb
elev_matrix = dataset + (9*6*(int_turbidity));
for(unsigned int i = 0; i < 9; ++i)
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] +=
(1.0-albedo) * (turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}

// alb 1 high turb
elev_matrix = dataset + (9*6*10 + 9*6*(int_turbidity));
for(unsigned int i = 0; i < 9; ++i)
{
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
config[i] +=
(albedo) * (turbidity_rem)
* ( pow(1.0-solar_elevation, 5.0) * elev_matrix[i] +
5.0 * pow(1.0-solar_elevation, 4.0) * solar_elevation * elev_matrix[i+9] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[i+18] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[i+27] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[i+36] +
pow(solar_elevation, 5.0) * elev_matrix[i+45]);
}
}

double ArHosekSkyModel_CookRadianceConfiguration(
ArHosekSkyModel_Radiance_Dataset dataset,
double turbidity,
double albedo,
double solar_elevation
)
{
double* elev_matrix;

int int_turbidity = turbidity;
double turbidity_rem = turbidity - (double)int_turbidity;
double res;
solar_elevation = pow(solar_elevation / (M_PI / 2.0), (1.0 / 3.0));

// alb 0 low turb
elev_matrix = dataset + (6*(int_turbidity-1));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res = (1.0-albedo) * (1.0 - turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);

// alb 1 low turb
elev_matrix = dataset + (6*10 + 6*(int_turbidity-1));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res += (albedo) * (1.0 - turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);
if(int_turbidity == 10)
return res;

// alb 0 high turb
elev_matrix = dataset + (6*(int_turbidity));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res += (1.0-albedo) * (turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);

// alb 1 high turb
elev_matrix = dataset + (6*10 + 6*(int_turbidity));
//(1-t).^3* A1 + 3*(1-t).^2.*t * A2 + 3*(1-t) .* t .^ 2 * A3 + t.^3 * A4;
res += (albedo) * (turbidity_rem) *
( pow(1.0-solar_elevation, 5.0) * elev_matrix[0] +
5.0*pow(1.0-solar_elevation, 4.0)*solar_elevation * elev_matrix[1] +
10.0*pow(1.0-solar_elevation, 3.0)*pow(solar_elevation, 2.0) * elev_matrix[2] +
10.0*pow(1.0-solar_elevation, 2.0)*pow(solar_elevation, 3.0) * elev_matrix[3] +
5.0*(1.0-solar_elevation)*pow(solar_elevation, 4.0) * elev_matrix[4] +
pow(solar_elevation, 5.0) * elev_matrix[5]);
return res;
}

double ArHosekSkyModel_GetRadianceInternal(
ArHosekSkyModelConfiguration configuration,
double theta,
double gamma
)
{
const double expM = exp(configuration[4] * gamma);
const double rayM = cos(gamma)*cos(gamma);
const double mieM = (1.0 + cos(gamma)*cos(gamma)) / pow((1.0 + configuration[8]*configuration[8] - 2.0*configuration[8]*cos(gamma)), 1.5);
const double zenith = sqrt(cos(theta));

return (1.0 + configuration[0] * exp(configuration[1] / (cos(theta) + 0.01))) *
(configuration[2] + configuration[3] * expM + configuration[5] * rayM + configuration[6] * mieM + configuration[7] * zenith);
}

// spectral version

ArHosekSkyModelState * arhosekskymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
)
{
ArHosekSkyModelState * state = ALLOC(ArHosekSkyModelState);

for( unsigned int wl = 0; wl < 11; ++wl )
{
ArHosekSkyModel_CookConfiguration(
datasets[wl],
state->configs[wl],
turbidity,
albedo,
elevation
);

state->radiances[wl] =
ArHosekSkyModel_CookRadianceConfiguration(
datasetsRad[wl],
turbidity,
albedo,
elevation
);
}

return state;
}

void arhosekskymodelstate_free(
ArHosekSkyModelState * state
)
{
free(state);
}

double arhosekskymodel_radiance(
ArHosekSkyModelState * state,
double theta,
double gamma,
double wavelength
)
{
int low_wl = (wavelength - 320.0 ) / 40.0;

double interp = fmod((wavelength - 320.0 ) / 40.0, 1.0);

double val_low =
ArHosekSkyModel_GetRadianceInternal(
state->configs[low_wl],
theta,
gamma
)
* state->radiances[low_wl];

if(interp < 1e-6)
return val_low;

double result =
(1.0 - interp)
* val_low
+ interp
* ArHosekSkyModel_GetRadianceInternal(
state->configs[low_wl+1],
theta,
gamma
)
* state->radiances[low_wl+1];

return result;
}


// xyz version

ArHosekXYZSkyModelState * arhosek_xyz_skymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
)
{
ArHosekXYZSkyModelState * state = ALLOC(ArHosekXYZSkyModelState);

for( unsigned int channel = 0; channel < 3; ++channel )
{
ArHosekSkyModel_CookConfiguration(
datasetsXYZ[channel],
state->configs[channel],
turbidity,
albedo,
elevation
);

state->radiances[channel] =
ArHosekSkyModel_CookRadianceConfiguration(
datasetsXYZRad[channel],
turbidity,
albedo,
elevation
);
}

return state;
}

void arhosek_xyz_skymodelstate_free(
ArHosekXYZSkyModelState * state
)
{
free(state);
}

double arhosek_xyz_skymodel_radiance(
ArHosekXYZSkyModelState * state,
double theta,
double gamma,
int channel
)
{
return
ArHosekSkyModel_GetRadianceInternal(
state->configs[channel],
theta,
gamma
)
* state->radiances[channel];
}
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