blender/intern/cycles/render/sky_model.cpp

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/*
This source is published under the following 3-clause BSD license.
Copyright (c) 2012 - 2013, 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 and
solar radiance models presented in the SIGGRAPH 2012 paper
"An Analytic Model for Full Spectral Sky-Dome Radiance"
and the 2013 IEEE CG&A paper
"Adding a Solar Radiance Function to the Hosek Skylight Model"
both by
Lukas Hosek and Alexander Wilkie
Charles University in Prague, Czech Republic
Version: 1.4a, February 22nd, 2013
Version history:
1.4a February 22nd, 2013
Removed unnecessary and counter-intuitive solar radius parameters
from the interface of the colourspace sky dome initialisation functions.
1.4 February 11th, 2013
Fixed a bug which caused the relative brightness of the solar disc
and the sky dome to be off by a factor of about 6. The sun was too
bright: this affected both normal and alien sun scenarios. The
coefficients of the solar radiance function were changed to fix this.
1.3 January 21st, 2013 (not released to the public)
Added support for solar discs that are not exactly the same size as
the terrestrial sun. Also added support for suns with a different
emission spectrum ("Alien World" functionality).
1.2a December 18th, 2012
Fixed a mistake and some inaccuracies in the solar radiance function
explanations found in ArHosekSkyModel.h. The actual source code is
unchanged compared to version 1.2.
1.2 December 17th, 2012
Native RGB data and a solar radiance function that matches the turbidity
conditions were added.
1.1 September 2012
The coefficients of the spectral model are now scaled so that the output
is given in physical units: W / (m^-2 * sr * nm). Also, the output of the
XYZ model is now no longer scaled to the range [0...1]. Instead, it is
the result of a simple conversion from spectral data via the CIE 2 degree
standard observer matching functions. Therefore, after multiplication
with 683 lm / W, the Y channel now corresponds to luminance in lm.
1.0 May 11th, 2012
Initial release.
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 in the accompanying header file.
*/
#include "sky_model.h"
#include "sky_model_data.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
CCL_NAMESPACE_BEGIN
// Some macro definitions that occur elsewhere in ART, and that have to be
// replicated to make this a stand-alone module.
#ifndef MATH_PI
#define MATH_PI 3.141592653589793
#endif
#ifndef MATH_DEG_TO_RAD
#define MATH_DEG_TO_RAD ( MATH_PI / 180.0 )
#endif
#ifndef DEGREES
#define DEGREES * MATH_DEG_TO_RAD
#endif
#ifndef TERRESTRIAL_SOLAR_RADIUS
#define TERRESTRIAL_SOLAR_RADIUS ( ( 0.51 DEGREES ) / 2.0 )
#endif
#ifndef ALLOC
#define ALLOC(_struct) ((_struct *)malloc(sizeof(_struct)))
#endif
// internal definitions
typedef double *ArHosekSkyModel_Dataset;
typedef double *ArHosekSkyModel_Radiance_Dataset;
// internal functions
static void ArHosekSkyModel_CookConfiguration(
ArHosekSkyModel_Dataset dataset,
ArHosekSkyModelConfiguration config,
double turbidity,
double albedo,
double solar_elevation
)
{
double * elev_matrix;
int int_turbidity = (int)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]);
}
}
static double ArHosekSkyModel_CookRadianceConfiguration(
ArHosekSkyModel_Radiance_Dataset dataset,
double turbidity,
double albedo,
double solar_elevation
)
{
double* elev_matrix;
int int_turbidity = (int)turbidity;
double turbidity_rem = turbidity - (double)int_turbidity;
double res;
solar_elevation = pow(solar_elevation / (MATH_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;
}
static 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);
}
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;
if ( low_wl < 0 || low_wl >= 11 )
return 0.0f;
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]
* state->emission_correction_factor_sky[low_wl];
if ( interp < 1e-6 )
return val_low;
double result = ( 1.0 - interp ) * val_low;
if ( low_wl+1 < 11 )
{
result +=
interp
* ArHosekSkyModel_GetRadianceInternal(
state->configs[low_wl+1],
theta,
gamma
)
* state->radiances[low_wl+1]
* state->emission_correction_factor_sky[low_wl+1];
}
return result;
}
// xyz and rgb versions
ArHosekSkyModelState * arhosek_xyz_skymodelstate_alloc_init(
const double turbidity,
const double albedo,
const double elevation
)
{
ArHosekSkyModelState * state = ALLOC(ArHosekSkyModelState);
state->solar_radius = TERRESTRIAL_SOLAR_RADIUS;
state->turbidity = turbidity;
state->albedo = albedo;
state->elevation = elevation;
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;
}
CCL_NAMESPACE_END