/* 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 #include #include // 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]; }