Browse Source

Integrate blackbody lighting with atmospheric scattering

master
C. J. Howard 3 years ago
parent
commit
272c871d15
10 changed files with 290 additions and 154 deletions
  1. +6
    -6
      src/ecs/components/atmosphere-component.hpp
  2. +15
    -0
      src/ecs/components/blackbody-component.hpp
  3. +158
    -121
      src/ecs/systems/astronomy-system.cpp
  4. +9
    -9
      src/ecs/systems/astronomy-system.hpp
  5. +3
    -4
      src/game/states/play-state.cpp
  6. +50
    -0
      src/physics/atmosphere.hpp
  7. +20
    -4
      src/physics/constants.hpp
  8. +2
    -2
      src/physics/light/photometry.hpp
  9. +24
    -8
      src/renderer/passes/sky-pass.cpp
  10. +3
    -0
      src/renderer/passes/sky-pass.hpp

+ 6
- 6
src/ecs/components/atmosphere-component.hpp View File

@ -27,19 +27,19 @@ namespace ecs {
/// Atmosphere
struct atmosphere_component
{
/// Radius of the outer atmosphere, in meters.
double exosphere_radius;
/// Altitude of the outer atmosphere, in meters.
double exosphere_altitude;
/// Rayleigh scale height
/// Rayleigh scale height, in meters.
double rayleigh_scale_height;
/// Mie scale height
/// Mie scale height, in meters.
double mie_scale_height;
/// Rayleigh scattering coefficients
/// (Dependent) Rayleigh scattering coefficients
double3 rayleigh_scattering_coefficients;
/// Mie scattering coefficients
/// (Dependent) Mie scattering coefficients
double3 mie_scattering_coefficients;
};

+ 15
- 0
src/ecs/components/blackbody-component.hpp View File

@ -27,6 +27,21 @@ struct blackbody_component
{
/// Effective temperature, in Kelvin.
double temperature;
/// 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;
};
} // namespace ecs

+ 158
- 121
src/ecs/systems/astronomy-system.cpp View File

@ -36,47 +36,64 @@
namespace ecs {
/**
* Calculates the optical depth between two points.
* Approximates the density of exponentially-distributed atmospheric particles between two points using the trapezoidal rule.
*
* @param start Start point.
* @param end End point.
* @param sample_count Number of samples to take between the start and end points.
* @param scale_height Scale height of the atmospheric particles to measure.
* @param a Start point.
* @param b End point.
* @param r Radius of the planet.
* @param sh Scale height of the atmospheric particles.
* @param n Number of samples.
*/
template <class T>
T transmittance(math::vector3<T> start, math::vector3<T> end, std::size_t sample_count, T scale_height)
T optical_depth(const math::vector3<T>& a, const math::vector3<T>& b, T r, T sh, std::size_t n)
{
const T inverse_scale_height = T(1) / -scale_height;
T inverse_sh = T(-1) / sh;
math::vector3<T> direction = end - start;
T distance = length(direction);
direction /= distance;
T h = math::length(b - a) / T(n);
// Calculate the distance between each sample point
T step_distance = distance / T(sample_count);
math::vector3<T> dy = (b - a) / T(n);
math::vector3<T> y = a + dy;
// Sum the atmospheric particle densities at each sample point
T total_density = 0.0;
math::vector3<T> sample_point = start;
for (std::size_t i = 0; i < sample_count; ++i)
T f_x = std::exp((length(a) - r) * inverse_sh);
T f_y = std::exp((length(y) - r) * inverse_sh);
T sum = (f_x + f_y);
for (std::size_t i = 1; i < n; ++i)
{
// Determine altitude of sample point
T altitude = length(sample_point);
// Calculate atmospheric particle density at sample altitude
T density = exp(altitude * inverse_scale_height);
// Add density to the total density
total_density += density;
// Advance to next sample point
sample_point += direction * step_distance;
f_x = f_y;
y += dy;
f_y = std::exp((length(y) - r) * inverse_sh);
sum += (f_x + f_y);
}
// Scale the total density by the step distance
return total_density * step_distance;
return sum / T(2) * h;
}
template <class T>
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_o = {0, 0, 0};
math::vector3<T> t = transmittance_r + transmittance_m + transmittance_o;
t.x = std::exp(-t.x);
t.y = std::exp(-t.y);
t.z = std::exp(-t.z);
return t;
}
double calc_beta_r(double wavelength, double ior, double density)
{
double wavelength2 = wavelength * wavelength;
double ior2m1 = ior * ior - 1.0;
double num = 8.0 * (math::pi<double> * math::pi<double> * math::pi<double>) * ior2m1 * ior2m1;
double den = 3.0 * density * (wavelength2 * wavelength2);
return num / den;
}
astronomy_system::astronomy_system(ecs::registry& registry):
entity_system(registry),
universal_time(0.0),
@ -86,7 +103,13 @@ astronomy_system::astronomy_system(ecs::registry& registry):
reference_body_axial_rotation(0.0),
sun_light(nullptr),
sky_pass(nullptr)
{}
{
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);
registry.on_construct<ecs::atmosphere_component>().connect<&astronomy_system::on_atmosphere_construct>(this);
registry.on_replace<ecs::atmosphere_component>().connect<&astronomy_system::on_atmosphere_replace>(this);
}
void astronomy_system::update(double t, double dt)
{
@ -130,59 +153,45 @@ void astronomy_system::update(double t, double dt)
transform.local.translation = math::type_cast<float>(r_topocentric);
});
// Get atmosphere component of reference body, if any
if (registry.has<ecs::atmosphere_component>(reference_body))
{
const ecs::atmosphere_component& atmosphere = registry.get<ecs::atmosphere_component>(reference_body);
}
if (sun_light != nullptr)
{
const math::vector3<double> sun_position_inertial = {0, 0, 0};
const math::vector3<double> sun_forward_inertial = math::normalize(reference_orbit.state.r - sun_position_inertial);
const math::vector3<double> sun_up_inertial = {0, 0, 1};
// Update blackbody lighting
registry.view<blackbody_component, orbit_component>().each(
[&](ecs::entity entity, auto& blackbody, auto& orbit)
{
// Calculate blackbody inertial basis
double3 blackbody_forward_inertial = math::normalize(reference_orbit.state.r - orbit.state.r);
double3 blackbody_up_inertial = {0, 0, 1};
// Transform sun position, forward, and up vectors into topocentric space
const math::vector3<double> sun_position_topocentric = inertial_to_topocentric * sun_position_inertial;
const math::vector3<double> sun_forward_topocentric = inertial_to_topocentric.rotation * sun_forward_inertial;
const math::vector3<double> sun_up_topocentric = inertial_to_topocentric.rotation * sun_up_inertial;
// Transform blackbody inertial position and basis into topocentric space
double3 blackbody_position_topocentric = inertial_to_topocentric * orbit.state.r;
double3 blackbody_forward_topocentric = inertial_to_topocentric.rotation * blackbody_forward_inertial;
double3 blackbody_up_topocentric = inertial_to_topocentric.rotation * blackbody_up_inertial;
// Update sun light transform
sun_light->set_translation(math::type_cast<float>(sun_position_topocentric));
sun_light->set_rotation
(
math::look_rotation
(
math::type_cast<float>(sun_forward_topocentric),
math::type_cast<float>(sun_up_topocentric)
)
);
// Calculate distance from observer to blackbody
const double meters_per_au = 1.496e+11;
double blackbody_distance = math::length(blackbody_position_topocentric) * meters_per_au;
// Convert sun topocentric Cartesian coordinates to spherical coordinates
math::vector3<double> sun_az_el = geom::cartesian::to_spherical(ezs_to_sez * sun_position_topocentric);
sun_az_el.z = math::pi<double> - sun_az_el.z;
// Calculate blackbody illuminance according to distance
double blackbody_illuminance = blackbody.luminous_intensity / (blackbody_distance * blackbody_distance);
//std::cout << "el: " << math::degrees(sun_az_el.y) << "; az: " << math::degrees(sun_az_el.z) << std::endl;
// Get blackbody color
double3 blackbody_color = blackbody.color;
// If the reference body has an atmosphere
if (registry.has<ecs::atmosphere_component>(reference_body))
// Get atmosphere component of reference body, if any
if (this->registry.has<ecs::atmosphere_component>(reference_body))
{
// Get the atmosphere component of the reference body
const auto& atmosphere = registry.get<ecs::atmosphere_component>(reference_body);
const ecs::atmosphere_component& atmosphere = this->registry.get<ecs::atmosphere_component>(reference_body);
const double meters_per_au = 1.496e+11;
const double earth_radius_au = 4.26352e-5;
const double earth_radius_m = earth_radius_au * meters_per_au;
const double observer_altitude_m = (observer_location[0] - earth_radius_au) * meters_per_au;
// Altitude of observer in meters
// Altitude of observer in meters
geom::ray<double> sample_ray;
sample_ray.origin = {0, observer_altitude_m, 0};
sample_ray.direction = math::normalize(sun_position_topocentric);
sample_ray.origin = {0, observer_location[0] * meters_per_au, 0};
sample_ray.direction = math::normalize(blackbody_position_topocentric);
geom::sphere<double> exosphere;
exosphere.center = {0, -earth_radius_m, 0};
exosphere.radius = atmosphere.exosphere_radius;
exosphere.center = {0, 0, 0};
exosphere.radius = earth_radius_m + atmosphere.exosphere_altitude;
auto intersection_result = geom::ray_sphere_intersection(sample_ray, exosphere);
@ -191,50 +200,44 @@ void astronomy_system::update(double t, double dt)
double3 sample_start = sample_ray.origin;
double3 sample_end = sample_ray.extrapolate(std::get<2>(intersection_result));
double transmittance_rayleigh = transmittance(sample_start, sample_end, 16, atmosphere.rayleigh_scale_height);
double transmittance_mie = transmittance(sample_start, sample_end, 16, atmosphere.mie_scale_height);
// Calculate attenuation due to atmospheric scattering
double3 scattering_attenuation =
atmosphere.rayleigh_scattering_coefficients * transmittance_rayleigh +
atmosphere.mie_scattering_coefficients * transmittance_mie;
scattering_attenuation.x = std::exp(-scattering_attenuation.x);
scattering_attenuation.y = std::exp(-scattering_attenuation.y);
scattering_attenuation.z = std::exp(-scattering_attenuation.z);
double scattering_mean = (scattering_attenuation.x + scattering_attenuation.y + scattering_attenuation.z) / 3.0;
const double sun_temperature = 5777.0;
const double sun_radius = 6.957e+8;
const double sun_surface_area = 4.0 * math::pi<double> * sun_radius * sun_radius;
// Calculate distance attenuation
double sun_distance_m = math::length(sun_position_topocentric) * meters_per_au;
double distance_attenuation = 1.0 / (sun_distance_m * sun_distance_m);
double sun_luminous_flux = blackbody_luminous_flux(sun_temperature, sun_radius);
double sun_luminous_intensity = sun_luminous_flux / (4.0 * math::pi<double>);
double sun_illuminance = sun_luminous_intensity / (sun_distance_m * sun_distance_m);
std::cout << "distance atten: " << distance_attenuation << std::endl;
std::cout << "scatter atten: " << scattering_attenuation << std::endl;
std::cout << "luminous flux: " << sun_luminous_flux << std::endl;
std::cout << "luminous intensity: " << sun_luminous_intensity << std::endl;
std::cout << "illuminance: " << sun_illuminance * scattering_mean << std::endl;
double optical_depth_r = optical_depth(sample_start, sample_end, earth_radius_m, atmosphere.rayleigh_scale_height, 32);
double optical_depth_k = optical_depth(sample_start, sample_end, earth_radius_m, atmosphere.mie_scale_height, 32);
double optical_depth_o = 0.0;
// Calculate sun color
double3 color_xyz = color::cct::to_xyz(sun_temperature);
double3 color_acescg = color::xyz::to_acescg(color_xyz);
double3 attenuation = transmittance(optical_depth_r, optical_depth_k, optical_depth_o, atmosphere.rayleigh_scattering_coefficients, atmosphere.mie_scattering_coefficients);
sun_light->set_color(math::type_cast<float>(color_acescg * scattering_attenuation));
sun_light->set_intensity(sun_illuminance);
// Attenuate blackbody color
blackbody_color *= attenuation;
}
}
}
if (sun_light != nullptr)
{
// Update blackbody light transform
sun_light->set_translation(math::type_cast<float>(blackbody_position_topocentric));
sun_light->set_rotation
(
math::look_rotation
(
math::type_cast<float>(blackbody_forward_topocentric),
math::type_cast<float>(blackbody_up_topocentric)
)
);
// 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));
// Pass blackbody params to sky pas
if (this->sky_pass)
{
this->sky_pass->set_sun_object(sun_light);
this->sky_pass->set_sun_color(math::type_cast<float>(blackbody.color * blackbody_illuminance));
}
}
});
// Update sky pass topocentric frame
if (sky_pass != nullptr)
{
sky_pass->set_topocentric_frame
@ -245,8 +248,6 @@ void astronomy_system::update(double t, double dt)
math::type_cast<float>(inertial_to_topocentric.rotation)
}
);
sky_pass->set_sun_object(sun_light);
}
}
@ -307,15 +308,26 @@ void astronomy_system::set_sky_pass(::sky_pass* pass)
this->sky_pass = pass;
}
double astronomy_system::blackbody_luminous_flux(double t, double r)
void astronomy_system::on_blackbody_construct(ecs::registry& registry, ecs::entity entity, ecs::blackbody_component& blackbody)
{
on_blackbody_replace(registry, entity, blackbody);
}
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);
// Blackbody spectral power distribution function
auto spd = [t](double x) -> double
auto spd = [blackbody](double x) -> double
{
// Convert nanometers to meters
x *= double(1e-9);
return physics::light::blackbody::spectral_radiance<double>(t, x, physics::constants::speed_of_light<double>);
return physics::light::blackbody::spectral_radiance<double>(blackbody.temperature, x, physics::constants::speed_of_light<double>);
};
// Luminous efficiency function (photopic)
@ -331,16 +343,41 @@ double astronomy_system::blackbody_luminous_flux(double t, double r)
// Calculate luminous efficiency
const double efficiency = physics::light::luminous_efficiency<double>(spd, lef, samples.begin(), samples.end());
// Calculate surface area of spherical blackbody
const double a = double(4) * math::pi<double> * r * r;
// Convert radiant flux to luminous flux
blackbody.luminous_flux = physics::light::watts_to_lumens<double>(blackbody.radiant_flux, efficiency);
// Calculate radiant flux
const double radiant_flux = physics::light::blackbody::radiant_flux(t, a);
// Calculate luminous intensity from luminous flux
blackbody.luminous_intensity = blackbody.luminous_flux / (4.0 * math::pi<double>);
// Convert radiant flux to luminous flux
const double luminous_flux = physics::light::watts_to_lumens<double>(radiant_flux, efficiency);
// Calculate blackbody color from temperature
double3 color_xyz = color::cct::to_xyz(blackbody.temperature);
blackbody.color = color::xyz::to_acescg(color_xyz);
}
void astronomy_system::on_atmosphere_construct(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere)
{
on_atmosphere_replace(registry, entity, atmosphere);
}
void astronomy_system::on_atmosphere_replace(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere)
{
// 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_nm = {600.0, 540.0, 450.0};
const double3 acescg_wavelengths_m = acescg_wavelengths_nm * 1.0e-9;
// Calculate Rayleigh scattering coefficients
const double air_ior = 1.0003;
const double molecular_density = 2.545e25;
double3 beta_r;
atmosphere.rayleigh_scattering_coefficients =
{
calc_beta_r(acescg_wavelengths_m.x, air_ior, molecular_density),
calc_beta_r(acescg_wavelengths_m.y, air_ior, molecular_density),
calc_beta_r(acescg_wavelengths_m.z, air_ior, molecular_density)
};
return luminous_flux;
// Calculate Mie scattering coefficients
atmosphere.mie_scattering_coefficients = {2.0e-6, 2.0e-6, 2.0e-6};
}
} // namespace ecs

+ 9
- 9
src/ecs/systems/astronomy-system.hpp View File

@ -26,11 +26,13 @@
#include "utility/fundamental-types.hpp"
#include "physics/frame.hpp"
#include "renderer/passes/sky-pass.hpp"
#include "ecs/components/blackbody-component.hpp"
#include "ecs/components/atmosphere-component.hpp"
namespace ecs {
/**
* Calculates apparent properties of celestial bodies relative to an observer (magnitude, angular radius, horizontal coordinates) and modifies their model component and/or light component to render them accordingly.
* Calculates apparent properties of celestial bodies relative to an observer.
*/
class astronomy_system:
public entity_system
@ -86,14 +88,12 @@ public:
void set_sky_pass(sky_pass* pass);
private:
/**
* Calculates the luminous flux of a spherical blackbody in vacuum using the CIE 1931 standard observer photopic luminosity function.
*
* @param t Temperature of the blackbody, in kelvin.
* @param r Radius of the blackbody, in meters.
* @return Luminous flux, in lumens.
*/
static double blackbody_luminous_flux(double t, double r);
void on_blackbody_construct(ecs::registry& registry, ecs::entity entity, ecs::blackbody_component& blackbody);
void on_blackbody_replace(ecs::registry& registry, ecs::entity entity, ecs::blackbody_component& blackbody);
void on_atmosphere_construct(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere);
void on_atmosphere_replace(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere);
double universal_time;
double time_scale;

+ 3
- 4
src/game/states/play-state.cpp View File

@ -114,7 +114,8 @@ void play_state_enter(game_context* ctx)
orbit.elements.ta = math::radians(0.0);
ecs::blackbody_component blackbody;
blackbody.temperature = 5772.0;
blackbody.temperature = 5777.0;
blackbody.radius = 6.957e+8;
ecs::transform_component transform;
transform.local = math::identity_transform<float>;
@ -139,11 +140,9 @@ void play_state_enter(game_context* ctx)
const double earth_radius_m = 6378e3;
ecs::atmosphere_component atmosphere;
atmosphere.exosphere_radius = earth_radius_m + 100e3;
atmosphere.exosphere_altitude = 80e3;
atmosphere.rayleigh_scale_height = 8000.0;
atmosphere.mie_scale_height = 1200.0;
atmosphere.rayleigh_scattering_coefficients = {5.8e-6, 1.35e-5, 3.31e-5};
atmosphere.mie_scattering_coefficients = {2e-6, 2e-6, 2e-6};
ecs::transform_component transform;
transform.local = math::identity_transform<float>;

+ 50
- 0
src/physics/atmosphere.hpp View File

@ -0,0 +1,50 @@
/*
* 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_ATMOSPHERE_HPP
#define ANTKEEPER_PHYSICS_ATMOSPHERE_HPP
#include "physics/constants.hpp"
#include <cmath>
namespace physics {
/// Atmosphere-related functions.
namespace atmosphere {
/**
* Calculates the density of exponentially-distributed atmospheric particles at a given altitude.
*
* @param d0 Density at sea level.
* @param z Height above sea level.
* @param sh Scale height of the particle type.
* @return Particle density at altitude.
*
* @see https://en.wikipedia.org/wiki/Scale_height
*/
T density(T d0, T z, T sh)
{
return d0 * std::exp(-z / sh);
}
} // namespace atmosphere
} // namespace physics
#endif // ANTKEEPER_PHYSICS_ATMOSPHERE_HPP

+ 20
- 4
src/physics/constants.hpp View File

@ -25,18 +25,34 @@ namespace physics {
/// Physical constants
namespace constants {
/**
* Avogadro number (N).
*
* @see https://physics.nist.gov/cgi-bin/cuu/Value?na
*/
template <class T>
constexpr T avogadro = T(6.02214076e+23);
/**
* Boltzmann constant (k), in joule per kelvin.
*
* @see https://physics.nist.gov/cgi-bin/cuu/Value?k|search_for=universal_in!
* @see https://physics.nist.gov/cgi-bin/cuu/Value?k
*/
template <class T>
constexpr T boltzmann = T(1.380649e-23);
/**
* Molar gas constant (R), in joule per kelvin per mole.
*
* @see https://en.wikipedia.org/wiki/Gas_constant
*/
template <class T>
constexpr T gas = T(8.31446261815324);
/**
* Gravitational constant (G), in cubic meter per second squared per kilogram.
*
* @see https://physics.nist.gov/cgi-bin/cuu/Value?G|search_for=universal_in!
* @see https://physics.nist.gov/cgi-bin/cuu/Value?G
*/
template <class T>
constexpr T gravitational = T(6.67430e-11);
@ -44,7 +60,7 @@ constexpr T gravitational = T(6.67430e-11);
/**
* Planck constant (h), in joule per hertz.
*
* @see https://physics.nist.gov/cgi-bin/cuu/Value?h|search_for=universal_in!
* @see https://physics.nist.gov/cgi-bin/cuu/Value?h
*/
template <class T>
constexpr T planck = T(6.62607015e-34);
@ -60,7 +76,7 @@ constexpr T stefan_boltzmann = T(5.670374419184429453970996731889230875840122970
/**
* Speed of light in vacuum (c), in meters per second.
*
* @see https://physics.nist.gov/cgi-bin/cuu/Value?c|search_for=universal_in!
* @see https://physics.nist.gov/cgi-bin/cuu/Value?c
*/
template <class T>
constexpr T speed_of_light = T(299792458);

+ 2
- 2
src/physics/light/photometry.hpp View File

@ -45,8 +45,8 @@ T luminous_efficiency(UnaryOp1 spd, UnaryOp2 lef, InputIt first, InputIt last)
return spd(x) * lef(x);
};
const T num = math::quadrature::trapezoid(spd_lef, first, last);
const T den = math::quadrature::trapezoid(spd, first, last);
const T num = math::quadrature::simpson(spd_lef, first, last);
const T den = math::quadrature::simpson(spd, first, last);
return num / den;
}

+ 24
- 8
src/renderer/passes/sky-pass.cpp View File

@ -43,6 +43,7 @@
#include "geom/cartesian.hpp"
#include "geom/spherical.hpp"
#include "physics/orbit/orbit.hpp"
#include "physics/light/photometry.hpp"
#include <cmath>
#include <stdexcept>
#include <glad/glad.h>
@ -68,6 +69,7 @@ sky_pass::sky_pass(gl::rasterizer* rasterizer, const gl::framebuffer* framebuffe
julian_day_tween(0.0, math::lerp<float, float>),
horizon_color_tween(float3{0.0f, 0.0f, 0.0f}, math::lerp<float3, float>),
zenith_color_tween(float3{1.0f, 1.0f, 1.0f}, math::lerp<float3, float>),
sun_color_tween(float3{1.0f, 1.0f, 1.0f}, math::lerp<float3, float>),
topocentric_frame_translation({0, 0, 0}, math::lerp<float3, float>),
topocentric_frame_rotation(math::quaternion<float>::identity(), math::nlerp<float>),
sun_object(nullptr)
@ -122,17 +124,17 @@ sky_pass::sky_pass(gl::rasterizer* rasterizer, const gl::framebuffer* framebuffe
// Calculate XYZ color from color temperature
double3 color_xyz = color::cct::to_xyz(cct);
// Transform XYZ from (assumed) D65 illuminant to ACES illuminant.
//color_xyz = color::xyz::cat::d65_to_aces(color_xyz);
// Transform XYZ color to ACEScg colorspace
double3 color_acescg = color::xyz::to_acescg(color_xyz);
// Convert apparent magnitude to lux
// Convert apparent magnitude to irradiance W/m2
double vmag_lux = astro::vmag_to_lux(vmag);
// Normalized color luminance and scale by apparent magnitude
double3 scaled_color = color_acescg * vmag_lux;
// Convert irradiance to illuminance (using luminous efficiency of sun)
double illuminance = physics::light::watts_to_lumens<double>(vmag_lux, 0.13);
// Scale color by illuminance
double3 scaled_color = color_acescg * illuminance;
// Build vertex
*(star_vertex++) = static_cast<float>(position_inertial.x);
@ -204,6 +206,8 @@ void sky_pass::render(render_context* context) const
float julian_day = julian_day_tween.interpolate(context->alpha);
float3 horizon_color = horizon_color_tween.interpolate(context->alpha);
float3 zenith_color = zenith_color_tween.interpolate(context->alpha);
float3 sun_color = sun_color_tween.interpolate(context->alpha);
// Construct tweened inertial to topocentric frame
physics::frame<float> topocentric_frame =
@ -233,6 +237,8 @@ void sky_pass::render(render_context* context) const
horizon_color_input->upload(horizon_color);
if (zenith_color_input)
zenith_color_input->upload(zenith_color);
if (sun_color_input)
sun_color_input->upload(sun_color);
if (mouse_input)
mouse_input->upload(mouse_position);
if (resolution_input)
@ -267,11 +273,14 @@ void sky_pass::render(render_context* context) const
rasterizer->draw_arrays(*sky_model_vao, sky_model_drawing_mode, sky_model_start_index, sky_model_index_count);
}
glEnable(GL_BLEND);
//glBlendFunc(GL_SRC_ALPHA, GL_ONE);
glBlendFunc(GL_ONE, GL_ONE);
// Draw moon model
if (moon_position.y >= -moon_angular_radius)
{
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);
float moon_distance = (clip_near + clip_far) * 0.5f;
float moon_radius = moon_angular_radius * moon_distance;
@ -370,6 +379,7 @@ void sky_pass::set_sky_model(const model* model)
model_view_projection_input = sky_shader_program->get_input("model_view_projection");
horizon_color_input = sky_shader_program->get_input("horizon_color");
zenith_color_input = sky_shader_program->get_input("zenith_color");
sun_color_input = sky_shader_program->get_input("sun_color");
mouse_input = sky_shader_program->get_input("mouse");
resolution_input = sky_shader_program->get_input("resolution");
time_input = sky_shader_program->get_input("time");
@ -437,6 +447,7 @@ void sky_pass::update_tweens()
zenith_color_tween.update();
topocentric_frame_translation.update();
topocentric_frame_rotation.update();
sun_color_tween.update();
}
void sky_pass::set_time_of_day(float time)
@ -503,6 +514,11 @@ void sky_pass::set_zenith_color(const float3& color)
zenith_color_tween[1] = color;
}
void sky_pass::set_sun_color(const float3& color)
{
sun_color_tween[1] = color;
}
void sky_pass::handle_event(const mouse_moved_event& event)
{
mouse_position = {static_cast<float>(event.x), static_cast<float>(event.y)};

+ 3
- 0
src/renderer/passes/sky-pass.hpp View File

@ -55,6 +55,7 @@ public:
void set_sky_model(const model* model);
void set_horizon_color(const float3& color);
void set_zenith_color(const float3& color);
void set_sun_color(const float3& color);
void set_time_of_day(float time);
void set_blue_noise_map(const gl::texture_2d* texture);
void set_sky_gradient(const gl::texture_2d* texture, const gl::texture_2d* texture2);
@ -91,6 +92,7 @@ private:
const gl::shader_input* sky_gradient_input;
const gl::shader_input* sky_gradient2_input;
const gl::shader_input* exposure_input;
const gl::shader_input* sun_color_input;
gl::shader_program* moon_shader_program;
const gl::shader_input* moon_model_view_projection_input;
@ -133,6 +135,7 @@ private:
tween<float> julian_day_tween;
tween<float3> horizon_color_tween;
tween<float3> zenith_color_tween;
tween<float3> sun_color_tween;
tween<float3> topocentric_frame_translation;
tween<math::quaternion<float>> topocentric_frame_rotation;

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