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Add more blackbody-related functions, add functions related to refraction, improve blackbody and atmosphere-related calculations in the astronomy system

master
C. J. Howard 3 months ago
parent
commit
4459d51367
16 changed files with 313 additions and 113 deletions
  1. +2
    -2
      src/ecs/components/atmosphere-component.hpp
  2. +2
    -11
      src/ecs/components/blackbody-component.hpp
  3. +40
    -52
      src/ecs/systems/astronomy-system.cpp
  4. +3
    -0
      src/ecs/systems/astronomy-system.hpp
  5. +3
    -0
      src/ecs/systems/tool-system.cpp
  6. +5
    -4
      src/game/states/play-state.cpp
  7. +2
    -2
      src/math/quadrature.hpp
  8. +14
    -11
      src/physics/atmosphere.hpp
  9. +98
    -11
      src/physics/light/blackbody.hpp
  10. +1
    -0
      src/physics/light/light.hpp
  11. +3
    -2
      src/physics/light/phase.hpp
  12. +8
    -4
      src/physics/light/photometry.hpp
  13. +117
    -0
      src/physics/light/refraction.hpp
  14. +2
    -1
      src/renderer/passes/shadow-map-pass.cpp
  15. +10
    -10
      src/renderer/passes/sky-pass.cpp
  16. +3
    -3
      src/renderer/passes/sky-pass.hpp

+ 2
- 2
src/ecs/components/atmosphere-component.hpp View File

@ -45,8 +45,8 @@ struct atmosphere_component
/// Mie scale height, in meters.
double mie_scale_height;
/// Mie phase function asymmetry factor.
double mie_asymmetry;
/// Mie phase function anisotropy factor.
double mie_anisotropy;
/// (Dependent) Rayleigh scattering coefficients at sea level.
double3 rayleigh_scattering;

+ 2
- 11
src/ecs/components/blackbody-component.hpp View File

@ -31,17 +31,8 @@ struct blackbody_component
/// Blackbody radius, in meters.
double radius;
/// (Dependent) Blackbody radiant flux, in watts.
double radiant_flux;
/// (Dependent) Blackbody luminous flux, in lumens.
double luminous_flux;
/// (Dependent) Blackbody luminous intensity, in lumens per steradian.
double luminous_intensity;
/// (Dependent) ACEScg color
double3 color;
/// (Dependent) RGB luminous intensity, in candela.
double3 luminous_intensity;
};
} // namespace ecs

+ 40
- 52
src/ecs/systems/astronomy-system.cpp View File

@ -30,7 +30,9 @@
#include "physics/light/blackbody.hpp"
#include "physics/light/photometry.hpp"
#include "physics/light/luminosity.hpp"
#include "physics/light/refraction.hpp"
#include "physics/atmosphere.hpp"
#include "math/quadrature.hpp"
#include "geom/cartesian.hpp"
#include <iostream>
@ -40,7 +42,7 @@ template
math::vector3<T> transmittance(T depth_r, T depth_m, T depth_o, const math::vector3<T>& beta_r, const math::vector3<T>& beta_m)
{
math::vector3<T> transmittance_r = beta_r * depth_r;
math::vector3<T> transmittance_m = beta_m * depth_m;
math::vector3<T> transmittance_m = beta_m * 1.1 * depth_m;
math::vector3<T> transmittance_o = {0, 0, 0};
math::vector3<T> t = transmittance_r + transmittance_m + transmittance_o;
@ -61,6 +63,10 @@ astronomy_system::astronomy_system(ecs::registry& registry):
sun_light(nullptr),
sky_pass(nullptr)
{
// RGB wavelengths determined by matching wavelengths to XYZ, transforming XYZ to ACEScg, then selecting the max wavelengths for R, G, and B.
rgb_wavelengths_nm = {602.224, 541.069, 448.143};
rgb_wavelengths_m = rgb_wavelengths_nm * 1e-9;
registry.on_construct<ecs::blackbody_component>().connect<&astronomy_system::on_blackbody_construct>(this);
registry.on_replace<ecs::blackbody_component>().connect<&astronomy_system::on_blackbody_replace>(this);
@ -128,13 +134,13 @@ void astronomy_system::update(double t, double dt)
// Calculate distance from observer to blackbody
double blackbody_distance = math::length(blackbody_position_topocentric);
// Calculate blackbody illuminance according to distance
double blackbody_illuminance = blackbody.luminous_intensity / (blackbody_distance * blackbody_distance);
// Calculate blackbody distance attenuation
double distance_attenuation = 1.0 / (blackbody_distance * blackbody_distance);
// Get blackbody color
double3 blackbody_color = blackbody.color;
// Init atmospheric transmittance
double3 atmospheric_transmittance = {1.0, 1.0, 1.0};
// Get atmosphere component of reference body, if any
// Get atmosphere component of reference body (if any)
if (this->registry.has<ecs::atmosphere_component>(reference_body))
{
const ecs::atmosphere_component& atmosphere = this->registry.get<ecs::atmosphere_component>(reference_body);
@ -159,10 +165,7 @@ void astronomy_system::update(double t, double dt)
double optical_depth_k = physics::atmosphere::optical_depth(sample_start, sample_end, earth_radius, atmosphere.mie_scale_height, 32);
double optical_depth_o = 0.0;
double3 attenuation = transmittance(optical_depth_r, optical_depth_k, optical_depth_o, atmosphere.rayleigh_scattering, atmosphere.mie_scattering);
// Attenuate blackbody color
blackbody_color *= attenuation;
atmospheric_transmittance = transmittance(optical_depth_r, optical_depth_k, optical_depth_o, atmosphere.rayleigh_scattering, atmosphere.mie_scattering);
}
}
@ -180,14 +183,14 @@ void astronomy_system::update(double t, double dt)
);
// Update blackbody light color and intensity
sun_light->set_color(math::type_cast<float>(blackbody_color));
sun_light->set_intensity(static_cast<float>(blackbody_illuminance));
sun_light->set_color(math::type_cast<float>(blackbody.luminous_intensity * atmospheric_transmittance));
sun_light->set_intensity(static_cast<float>(distance_attenuation));
// Upload blackbody params to sky pass
if (this->sky_pass)
{
this->sky_pass->set_sun_position(math::type_cast<float>(blackbody_position_topocentric));
this->sky_pass->set_sun_color(math::type_cast<float>(blackbody.color * blackbody_illuminance));
this->sky_pass->set_sun_color(math::type_cast<float>(blackbody.luminous_intensity * distance_attenuation));
double blackbody_angular_radius = std::asin((blackbody.radius * 2.0) / (blackbody_distance * 2.0));
this->sky_pass->set_sun_angular_radius(static_cast<float>(blackbody_angular_radius));
@ -219,7 +222,7 @@ void astronomy_system::update(double t, double dt)
sky_pass->set_scale_heights(atmosphere.rayleigh_scale_height, atmosphere.mie_scale_height);
sky_pass->set_scattering_coefficients(math::type_cast<float>(atmosphere.rayleigh_scattering), math::type_cast<float>(atmosphere.mie_scattering));
sky_pass->set_mie_asymmetry(atmosphere.mie_asymmetry);
sky_pass->set_mie_anisotropy(atmosphere.mie_anisotropy);
sky_pass->set_atmosphere_radii(earth_radius, earth_radius + atmosphere.exosphere_altitude);
}
}
@ -289,43 +292,31 @@ void astronomy_system::on_blackbody_construct(ecs::registry& registry, ecs::enti
void astronomy_system::on_blackbody_replace(ecs::registry& registry, ecs::entity entity, ecs::blackbody_component& blackbody)
{
// Calculate surface area of spherical blackbody
const double surface_area = double(4) * math::pi<double> * blackbody.radius * blackbody.radius;
// Calculate radiant flux
blackbody.radiant_flux = physics::light::blackbody::radiant_flux(blackbody.temperature, surface_area);
// Calculate the surface area of a spherical blackbody
const double surface_area = 4.0 * math::pi<double> * blackbody.radius * blackbody.radius;
// Blackbody spectral power distribution function
auto spd = [blackbody](double x) -> double
// Construct a lambda function which calculates the blackbody's RGB luminous intensity of a given wavelength
auto rgb_luminous_intensity = [blackbody, surface_area](double wavelength_nm) -> double3
{
// Convert nanometers to meters
x *= double(1e-9);
// Convert wavelength from nanometers to meters
const double wavelength_m = wavelength_nm * 1e-9;
return physics::light::blackbody::spectral_radiance<double>(blackbody.temperature, x, physics::constants::speed_of_light<double>);
};
// Luminous efficiency function (photopic)
auto lef = [](double x) -> double
{
return physics::light::luminosity::photopic<double>(x);
// Calculate the spectral intensity of the wavelength
const double spectral_intensity = physics::light::blackbody::spectral_intensity<double>(blackbody.temperature, surface_area, wavelength_m);
// Calculate the ACEScg color of the wavelength using CIE color matching functions
double3 spectral_color = color::xyz::to_acescg(color::xyz::match(wavelength_nm));
// Scale the spectral color by spectral intensity
return spectral_color * spectral_intensity * 1e-9 * physics::light::max_luminous_efficacy<double>;
};
// Construct range of spectral sample points
std::vector<double> samples(10000);
std::iota(samples.begin(), samples.end(), 10);
// Calculate luminous efficiency
const double efficiency = physics::light::luminous_efficiency<double>(spd, lef, samples.begin(), samples.end());
// Construct a range of sample wavelengths in the visible spectrum
std::vector<double> samples(780 - 280);
std::iota(samples.begin(), samples.end(), 280);
// Convert radiant flux to luminous flux
blackbody.luminous_flux = physics::light::watts_to_lumens<double>(blackbody.radiant_flux, efficiency);
// Calculate luminous intensity from luminous flux
blackbody.luminous_intensity = blackbody.luminous_flux / (4.0 * math::pi<double>);
// Calculate blackbody color from temperature
double3 color_xyz = color::cct::to_xyz(blackbody.temperature);
blackbody.color = color::xyz::to_acescg(color_xyz);
// Integrate the blackbody RGB luminous intensity over wavelengths in the visible spectrum
blackbody.luminous_intensity = math::quadrature::simpson(rgb_luminous_intensity, samples.begin(), samples.end());
}
void astronomy_system::on_atmosphere_construct(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere)
@ -339,19 +330,16 @@ void astronomy_system::on_atmosphere_replace(ecs::registry& registry, ecs::entit
const double rayleigh_polarization = physics::atmosphere::polarization(atmosphere.index_of_refraction, atmosphere.rayleigh_density);
const double mie_polarization = physics::atmosphere::polarization(atmosphere.index_of_refraction, atmosphere.mie_density);
// ACEScg wavelengths determined by matching wavelengths to XYZ, transforming XYZ to ACEScg, then selecting the max wavelengths for R, G, and B.
const double3 acescg_wavelengths = {600.0e-9, 540.0e-9, 450.0e-9};
// Calculate Rayleigh scattering coefficients
atmosphere.rayleigh_scattering =
{
physics::atmosphere::scatter_rayleigh(acescg_wavelengths.x, atmosphere.rayleigh_density, rayleigh_polarization),
physics::atmosphere::scatter_rayleigh(acescg_wavelengths.y, atmosphere.rayleigh_density, rayleigh_polarization),
physics::atmosphere::scatter_rayleigh(acescg_wavelengths.z, atmosphere.rayleigh_density, rayleigh_polarization)
physics::atmosphere::scattering_rayleigh(rgb_wavelengths_m.x, atmosphere.rayleigh_density, rayleigh_polarization),
physics::atmosphere::scattering_rayleigh(rgb_wavelengths_m.y, atmosphere.rayleigh_density, rayleigh_polarization),
physics::atmosphere::scattering_rayleigh(rgb_wavelengths_m.z, atmosphere.rayleigh_density, rayleigh_polarization)
};
// Calculate Mie scattering coefficients
const double mie_scattering = physics::atmosphere::scatter_mie(atmosphere.mie_density, mie_polarization);
const double mie_scattering = physics::atmosphere::scattering_mie(atmosphere.mie_density, mie_polarization);
atmosphere.mie_scattering =
{
mie_scattering,

+ 3
- 0
src/ecs/systems/astronomy-system.hpp View File

@ -109,6 +109,9 @@ private:
physics::frame<double> inertial_to_topocentric;
physics::frame<double> sez_to_ezs;
physics::frame<double> ezs_to_sez;
double3 rgb_wavelengths_nm;
double3 rgb_wavelengths_m;
};
} // namespace ecs

+ 3
- 0
src/ecs/systems/tool-system.cpp View File

@ -292,6 +292,9 @@ void tool_system::set_active_tool(ecs::entity entity)
void tool_system::set_tool_active(bool active)
{
if (active_tool == entt::null)
return;
tool_active = active;
if (active)

+ 5
- 4
src/game/states/play-state.cpp View File

@ -130,15 +130,15 @@ void play_state_enter(game_context* ctx)
orbit.elements.ta = math::radians(100.46457166) - longitude_periapsis;
ecs::atmosphere_component atmosphere;
atmosphere.exosphere_altitude = 100e3;
atmosphere.exosphere_altitude = 65e3;
atmosphere.index_of_refraction = 1.0003;
atmosphere.index_of_refraction = 1.000293;
atmosphere.rayleigh_density = 2.545e25;
atmosphere.mie_density = 14.8875;
atmosphere.rayleigh_scale_height = 8000.0;
atmosphere.mie_scale_height = 1200.0;
atmosphere.mie_asymmetry = 0.8;
atmosphere.mie_anisotropy = 0.8;
ecs::transform_component transform;
transform.local = math::identity_transform<float>;
@ -230,7 +230,7 @@ void play_state_enter(game_context* ctx)
ecs::command::assign_render_layers(ecs_registry, ctx->twig_entity, 0);
// Activate brush tool
ctx->tool_system->set_active_tool(ctx->brush_entity);
//ctx->tool_system->set_active_tool(ctx->brush_entity);
// Create ant-hill
auto ant_hill_entity = ant_hill_archetype->create(ecs_registry);
@ -291,6 +291,7 @@ void play_state_enter(game_context* ctx)
// Setup camera
ctx->overworld_camera->look_at({0, 0, 1}, {0, 0, 0}, {0, 1, 0});
ctx->overworld_camera->set_exposure(-14.5f);
ctx->camera_system->set_camera(ctx->overworld_camera);
ctx->overworld_scene->update_tweens();

+ 2
- 2
src/math/quadrature.hpp View File

@ -63,7 +63,7 @@ typename std::invoke_result::val
typedef decltype(*last - *first) difference_type;
if (first == last)
return output_type(0);
return output_type{0};
output_type f_a = f(*first);
@ -102,7 +102,7 @@ typename std::invoke_result::val
typedef decltype(*last - *first) difference_type;
if (first == last)
return output_type(0);
return output_type{0};
output_type f_a = f(*first);

+ 14
- 11
src/physics/atmosphere.hpp View File

@ -46,19 +46,20 @@ T density(T d0, T z, T sh)
}
/**
* Calculates a particle polarization factor used in computing scattering coefficients.
* Calculates a particle polarizability factor used in computing scattering coefficients.
*
* @param ior Atmospheric index of refraction.
* @param density Molecular density.
* @return Polarization factor.
*
* @see Elek, Oskar. (2009). Rendering Parametrizable Planetary Atmospheres with Multiple Scattering in Real-Time.
* @see Real-Time Spectral Scattering in Large-Scale Natural Participating Media.
*/
template <class T>
T polarization(T ior, T density)
{
const T ior2 = ior * ior;
const T num = T(2) * math::pi<T> * math::pi<T> * ((ior2 - T(1.0)) * (ior2 - T(1.0)));
const T ior2m1 = ior * ior - T(1.0);
const T num = T(2) * math::pi<T> * math::pi<T> * ior2m1 * ior2m1;
const T den = T(3) * density * density;
return num / den;
}
@ -73,9 +74,10 @@ T polarization(T ior, T density)
* @see atmosphere::polarization
*
* @see Elek, Oskar. (2009). Rendering Parametrizable Planetary Atmospheres with Multiple Scattering in Real-Time.
* @see Real-Time Spectral Scattering in Large-Scale Natural Participating Media.
*/
template <class T>
T scatter_rayleigh(T wavelength, T density, T polarization)
T scattering_rayleigh(T wavelength, T density, T polarization)
{
const T wavelength2 = wavelength * wavelength;
return T(4) * math::pi<T> * density / (wavelength2 * wavelength2) * polarization;
@ -90,24 +92,25 @@ T scatter_rayleigh(T wavelength, T density, T polarization)
* @see atmosphere::polarization
*
* @see Elek, Oskar. (2009). Rendering Parametrizable Planetary Atmospheres with Multiple Scattering in Real-Time.
* @see Real-Time Spectral Scattering in Large-Scale Natural Participating Media.
*/
template <class T>
T scatter_mie(T density, T polarization)
T scattering_mie(T density, T polarization)
{
return T(4) * math::pi<T> * density * polarization;
}
/**
* Calculates an extinction coefficient given a scattering coefficient and an absorbtion coefficient.
* Calculates attenuation due to extinction (absorption + out-scattering).
*
* @param s Scattering coefficient.
* @param a Absorbtion coefficient.
* @return Extinction coefficient.
* @param ec Extinction coefficient (absorption coefficient + scattering coefficient).
* @param s Scale factor.
* @return Attenuation factor.
*/
template <class T>
T extinction(T s, T a)
T extinction(T ec, T s)
{
return s + a;
return std::exp(-(ec * s));
}
/**

+ 98
- 11
src/physics/light/blackbody.hpp View File

@ -22,13 +22,14 @@
#include "math/constants.hpp"
#include "physics/constants.hpp"
#include "physics/planck.hpp"
namespace physics {
namespace light {
/**
* Blackbody radiation functions.
*
* @see https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
*/
namespace blackbody {
@ -37,9 +38,6 @@ namespace blackbody {
*
* @param t Temperature of the blackbody, in kelvin.
* @return Radiant exitance of the blackbody, in watt per square meter.
*
* @see https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
* @see https://en.wikipedia.org/wiki/Radiant_exitance
*/
template <class T>
T radiant_exitance(T t);
@ -49,25 +47,66 @@ T radiant_exitance(T t);
*
* @param t Temperature of the blackbody, in kelvin.
* @param a Surface area of the blackbody, in square meters.
* @return Radiant power of the blackbody, in watts.
*
* @see https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
* @return Radiant flux of the blackbody, in watt.
*/
template <class T>
T radiant_flux(T t, T a);
/**
* Calculates the spectral radiance of a blackbody at a given wavelength.
* Calculates the radiant intensity of a blackbody.
*
* @param t Temperature of the blackbody, in kelvin.
* @param a Surface area of the blackbody, in square meters.
* @return Radiant intensity of the blackbody, in watt per steradian.
*/
template <class T>
T radiant_intensity(T t, T a);
/**
* Calculates the spectral exitance of a blackbody for the given wavelength.
*
* @param t Temperature of the blackbody, in kelvin.
* @param lambda Wavelength of light, in meters.
* @param c Speed of light in medium.
* @return Spectral radiance, in watt per steradian per square meter per meter.
* @return Spectral exitance, in watt per square meter, per meter.
*/
template <class T>
T spectral_exitance(T t, T lambda, T c = constants::speed_of_light<T>);
/**
* Calculates the spectral flux of a blackbody for the given wavelength.
*
* @param t Temperature of the blackbody, in kelvin.
* @param a Surface area of the blackbody, in square meters.
* @param lambda Wavelength of light, in meters.
* @param c Speed of light in medium.
* @return Spectral flux of the blackbody, in watt per meter.
*/
template <class T>
T spectral_flux(T t, T a, T lambda, T c = constants::speed_of_light<T>);
/**
* Calculates the spectral intensity of a blackbody for the given wavelength.
*
* @param t Temperature of the blackbody, in kelvin.
* @param a Surface area of the blackbody, in square meters.
* @param lambda Wavelength of light, in meters.
* @param c Speed of light in medium.
* @return Spectral intensity of the blackbody for the given wavelength, in watt per steradian per meter.
*/
template <class T>
T spectral_intensity(T t, T a, T lambda, T c = constants::speed_of_light<T>);
/**
* Calculates the spectral radiance of a blackbody for the given wavelength.
*
* @see physics::planck::wavelength
* @param t Temperature of the blackbody, in kelvin.
* @param lambda Wavelength of light, in meters.
* @param c Speed of light in medium.
* @return Spectral radiance, in watt per steradian per square meter per meter.
*/
template <class T>
constexpr auto spectral_radiance = planck::wavelength<T>;
T spectral_radiance(T t, T lambda, T c = constants::speed_of_light<T>);
template <class T>
T radiant_exitance(T t)
@ -82,6 +121,54 @@ T radiant_flux(T t, T a)
return a * radiant_exitance(t);
}
template <class T>
T radiant_intensity(T t, T a)
{
return radiant_flux(t, a) / (T(4) * math::pi<T>);
}
template <class T>
T spectral_exitance(T t, T lambda, T c)
{
const T hc = constants::planck<T> * c;
const T lambda2 = lambda * lambda;
// First radiation constant (c1)
const T c1 = T(2) * math::pi<T> * hc * c;
// Second radiation constant (c2)
const T c2 = hc / constants::boltzmann<T>;
return (c1 / (lambda2 * lambda2 * lambda)) / std::expm1(c2 / (lambda * t));
}
template <class T>
T spectral_flux(T t, T a, T lambda, T c)
{
return a * spectral_exitance(t, lambda, c);
}
template <class T>
T spectral_intensity(T t, T a, T lambda, T c)
{
return spectral_flux(t, a, lambda, c) / (T(4) * math::pi<T>);
}
template <class T>
T spectral_radiance(T t, T lambda, T c)
{
const T hc = constants::planck<T> * c;
const T lambda2 = lambda * lambda;
// First radiation constant (c1L)
const T c1l = T(2) * hc * c;
// Second radiation constant (c2)
const T c2 = hc / constants::boltzmann<T>;
return (c1l / (lambda2 * lambda2 * lambda)) / std::expm1(c2 / (lambda * t));
}
} // namespace blackbody
} // namespace light

+ 1
- 0
src/physics/light/light.hpp View File

@ -31,5 +31,6 @@ namespace light {}
#include "luminosity.hpp"
#include "phase.hpp"
#include "photometry.hpp"
#include "refraction.hpp"
#endif // ANTKEEPER_PHYSICS_LIGHT_HPP

+ 3
- 2
src/physics/light/phase.hpp View File

@ -69,7 +69,7 @@ T rayleigh(T mu);
template <class T>
T cornette_shanks(T mu, T g)
{
const T k = T(3) / (T(8) * math::pi<T>);
static const T k = T(3) / (T(8) * math::pi<T>);
const T gg = g * g;
const T num = (T(1) - gg) * (T(1) + mu * mu);
const T den = (T(2) + gg) * std::pow(T(1) + gg - T(2) * g * mu, T(1.5));
@ -86,7 +86,8 @@ T henyey_greenstein(T mu, T g)
template <class T>
T rayleigh(T mu)
{
return (T(1) + mu * mu) * (T(3) / (T(16) * math::pi<T>));
static const T k = T(3) / (T(16) * math::pi<T>);
return k * (1.0 + mu * mu);
}
} // namespace phase

+ 8
- 4
src/physics/light/photometry.hpp View File

@ -26,6 +26,10 @@
namespace physics {
namespace light {
/// Maximum luminous efficacy of an ideal monochromatic source, in lumen per watt.
template <class T>
constexpr T max_luminous_efficacy = T(683.002);
/**
* Calculates the luminous efficiency of a light source.
*
@ -60,20 +64,20 @@ T luminous_efficiency(UnaryOp1 spd, UnaryOp2 lef, InputIt first, InputIt last)
template <class T>
T luminous_efficacy(T efficiency)
{
return T(683.002) * efficiency;
return max_luminous_efficacy<T> * efficiency;
}
/**
* Converts watts (radiant flux) to lumens (luminous flux).
*
* @param radient_flux Radiance flux, in watts.
* @param radiant_flux Radiant flux, in watts.
* @param efficiency Luminous efficiency, on `[0, 1]`.
* @return Luminous flux, in lumens.
*/
template <class T>
T watts_to_lumens(T radient_flux, T efficiency)
T watts_to_lumens(T radiant_flux, T efficiency)
{
return radient_flux * luminous_efficacy(efficiency);
return radiant_flux * luminous_efficacy(efficiency);
}
} // namespace light

+ 117
- 0
src/physics/light/refraction.hpp View File

@ -0,0 +1,117 @@
/*
* Copyright (C) 2021 Christopher J. Howard
*
* This file is part of Antkeeper source code.
*
* Antkeeper source code is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Antkeeper source code 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef ANTKEEPER_PHYSICS_LIGHT_REFRACTION_HPP
#define ANTKEEPER_PHYSICS_LIGHT_REFRACTION_HPP
namespace physics {
namespace light {
/// Index of refraction formulas.
namespace ior {
/**
* Two-term form of Cauchy's transmission equation.
*
* @param lambda Wavelength of light, in micrometers.
* @param a First coefficient of the medium.
* @param b Second coefficient of the medium.
* @return Refractive index.
*
* @see https://en.wikipedia.org/wiki/Cauchy%27s_equation
*/
template <class T>
T cauchy(T lambda, T a, T b)
{
return a + b / (lambda * lambda);
}
/**
* Three-term form of Cauchy's transmission equation.
*
* @param lambda Wavelength of light, in micrometers.
* @param a First coefficient.
* @param b Second coefficient.
* @param c Third coefficient.
* @return Refractive index.
*
* @see https://en.wikipedia.org/wiki/Cauchy%27s_equation
*/
template <class T>
T cauchy(T lambda, T a, T b, T c)
{
const T lambda2 = lambda * lambda;
return a + b / lambda2 + c / (lambda2 * lambda2);
}
/**
* Two-term form of the Sellmeier equation.
*
* @param lambda Wavelength of light, in micrometers.
* @param b1 B1 coefficient.
* @param c1 C1 coefficient.
* @param b2 B2 coefficient.
* @param c2 C2 coefficient.
* @return Refractive index.
*
* @see https://en.wikipedia.org/wiki/Sellmeier_equation
*/
template <class T>
T sellmeier(T lambda, T b1, T c1, T b2, T c2)
{
const T lambda2 = lambda * lambda;
const T t1 = (b1 * lambda2) / (lambda2 - c1);
const T t2 = (b2 * lambda2) / (lambda2 - c2);
return std::sqrt(T(1) + t1 + t2);
}
/**
* Three-term form of the Sellmeier equation.
*
* @param lambda Wavelength of light, in micrometers.
* @param b1 B1 coefficient.
* @param c1 C1 coefficient.
* @param b2 B2 coefficient.
* @param c2 C2 coefficient.
* @param b3 B3 coefficient.
* @param c3 C3 coefficient.
* @return Refractive index.
*
* @see https://en.wikipedia.org/wiki/Sellmeier_equation
*/
template <class T>
T sellmeier(T lambda, T b1, T c1, T b2, T c2, T b3, T c3)
{
const T lambda2 = lambda * lambda;
const T t1 = (b1 * lambda2) / (lambda2 - c1);
const T t2 = (b2 * lambda2) / (lambda2 - c2);
const T t3 = (b3 * lambda2) / (lambda2 - c3);
return std::sqrt(T(1) + t1 + t2 + t3);
}
} // namespace ior
} // namespace light
} // namespace physics
#endif // ANTKEEPER_PHYSICS_LIGHT_REFRACTION_HPP

+ 2
- 1
src/renderer/passes/shadow-map-pass.cpp View File

@ -103,7 +103,8 @@ void shadow_map_pass::render(render_context* context) const
glDepthMask(GL_TRUE);
// Disable face culling
glDisable(GL_CULL_FACE);
glEnable(GL_CULL_FACE);
glCullFace(GL_FRONT);
// For half-z buffer
//glDepthRange(-1.0f, 1.0f);

+ 10
- 10
src/renderer/passes/sky-pass.cpp View File

@ -122,14 +122,14 @@ sky_pass::sky_pass(gl::rasterizer* rasterizer, const gl::framebuffer* framebuffe
// Transform XYZ color to ACEScg colorspace
double3 color_acescg = color::xyz::to_acescg(color_xyz);
// Convert apparent magnitude to irradiance W/m2
double vmag_lux = astro::vmag_to_lux(vmag);
// Convert apparent magnitude to irradiance (W/m^2)
double vmag_irradiance = std::pow(10.0, 0.4 * (-vmag - 19.0 + 0.4));
// Convert irradiance to illuminance (using luminous efficiency of sun)
double illuminance = physics::light::watts_to_lumens<double>(vmag_lux, 0.13);
// Convert irradiance to illuminance
double vmag_illuminance = vmag_irradiance * (683.0 * 0.14);
// Scale color by illuminance
double3 scaled_color = color_acescg * illuminance;
double3 scaled_color = color_acescg * vmag_illuminance;
// Build vertex
*(star_vertex++) = static_cast<float>(position_inertial.x);
@ -244,8 +244,8 @@ void sky_pass::render(render_context* context) const
rayleigh_scattering_input->upload(rayleigh_scattering);
if (mie_scattering_input)
mie_scattering_input->upload(mie_scattering);
if (mie_asymmetry_input)
mie_asymmetry_input->upload(mie_asymmetry);
if (mie_anisotropy_input)
mie_anisotropy_input->upload(mie_anisotropy);
if (atmosphere_radii_input)
atmosphere_radii_input->upload(atmosphere_radii);
@ -351,7 +351,7 @@ void sky_pass::set_sky_model(const model* model)
scale_height_rm_input = sky_shader_program->get_input("scale_height_rm");
rayleigh_scattering_input = sky_shader_program->get_input("rayleigh_scattering");
mie_scattering_input = sky_shader_program->get_input("mie_scattering");
mie_asymmetry_input = sky_shader_program->get_input("mie_asymmetry");
mie_anisotropy_input = sky_shader_program->get_input("mie_anisotropy");
atmosphere_radii_input = sky_shader_program->get_input("atmosphere_radii");
}
}
@ -449,9 +449,9 @@ void sky_pass::set_scattering_coefficients(const float3& r, const float3& m)
mie_scattering = m;
}
void sky_pass::set_mie_asymmetry(float g)
void sky_pass::set_mie_anisotropy(float g)
{
mie_asymmetry = {g, g * g};
mie_anisotropy = {g, g * g};
}
void sky_pass::set_atmosphere_radii(float inner, float outer)

+ 3
- 3
src/renderer/passes/sky-pass.hpp View File

@ -64,7 +64,7 @@ public:
void set_observer_altitude(float altitude);
void set_scale_heights(float rayleigh, float mie);
void set_scattering_coefficients(const float3& r, const float3& m);
void set_mie_asymmetry(float g);
void set_mie_anisotropy(float g);
void set_atmosphere_radii(float inner, float outer);
private:
@ -84,7 +84,7 @@ private:
const gl::shader_input* scale_height_rm_input;
const gl::shader_input* rayleigh_scattering_input;
const gl::shader_input* mie_scattering_input;
const gl::shader_input* mie_asymmetry_input;
const gl::shader_input* mie_anisotropy_input;
const gl::shader_input* atmosphere_radii_input;
gl::shader_program* moon_shader_program;
@ -132,7 +132,7 @@ private:
float2 scale_height_rm;
float3 rayleigh_scattering;
float3 mie_scattering;
float2 mie_asymmetry;
float2 mie_anisotropy;
float3 atmosphere_radii;
};

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