Separate atmospheric scattering-related functions out of astronomy system and into new atmosphere system

CMakeLists.txt

@@ -1,5 +1,6 @@
 cmake_minimum_required(VERSION 3.7)
 
+
 option(VERSION_STRING "Project version string" "0.0.0")
 
 project(antkeeper VERSION ${VERSION_STRING} LANGUAGES CXX)

src/ecs/systems/astronomy-system.cpp

@@ -59,14 +59,7 @@ astronomy_system::astronomy_system(ecs::registry& registry):
 	reference_atmosphere(nullptr),
 	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::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)
 {
@@ -93,8 +86,8 @@ void astronomy_system::update(double t, double dt)
 	inertial_to_topocentric = inertial_to_bcbf * bcbf_to_topocentric;
 	
 	// Set the transform component translations of orbiting bodies to their topocentric positions
-	registry.view<orbit_component, transform_component>().each(
-	[&](ecs::entity entity, const auto& orbit, auto& transform)
+	registry.view<celestial_body_component, orbit_component, transform_component>().each(
+	[&](ecs::entity entity, const auto& celestial_body, const auto& orbit, auto& transform)
 	{
 		// Transform Cartesian position vector (r) from inertial space to topocentric space
 		const math::vector3<double> r_topocentric = inertial_to_topocentric * orbit.state.r;
@@ -276,33 +269,4 @@ void astronomy_system::set_sky_pass(::sky_pass* pass)
 	this->sky_pass = pass;
 }
 
-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)
-{
-	// Calculate polarization factors
-	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);
-	
-	// Calculate Rayleigh scattering coefficients
-	atmosphere.rayleigh_scattering =
-	{
-		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::scattering_mie(atmosphere.mie_density, mie_polarization);
-	atmosphere.mie_scattering = 
-	{
-		mie_scattering,
-		mie_scattering,
-		mie_scattering
-	};
-}
-
 } // namespace ecs

src/ecs/systems/astronomy-system.hpp

@@ -82,15 +82,9 @@ public:
 	void set_sky_pass(sky_pass* pass);
 	
 private:
-	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;
 	
-	double3 rgb_wavelengths_nm;
-	double3 rgb_wavelengths_m;
-	
 	ecs::entity reference_entity;
 	const ecs::orbit_component* reference_orbit;
 	const ecs::celestial_body_component* reference_body;

src/ecs/systems/atmosphere-system.cpp

@@ -0,0 +1,80 @@
+/*
+ * 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/>.
+ */
+
+#include "ecs/systems/atmosphere-system.hpp"
+#include "physics/atmosphere.hpp"
+
+namespace ecs {
+
+atmosphere_system::atmosphere_system(ecs::registry& registry):
+	entity_system(registry)
+{
+	// 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::atmosphere_component>().connect<&atmosphere_system::on_atmosphere_construct>(this);
+	registry.on_replace<ecs::atmosphere_component>().connect<&atmosphere_system::on_atmosphere_replace>(this);
+}
+
+void atmosphere_system::update(double t, double dt)
+{}
+
+void atmosphere_system::update_coefficients(ecs::entity entity)
+{
+	// Abort if entity has no atmosphere component
+	if (!registry.has<atmosphere_component>(entity))
+		return;
+	
+	// Get atmosphere component of the entity
+	atmosphere_component& atmosphere = registry.get<atmosphere_component>(entity);
+	
+	// Calculate polarization factors
+	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);
+	
+	// Calculate Rayleigh scattering coefficients
+	atmosphere.rayleigh_scattering =
+	{
+		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::scattering_mie(atmosphere.mie_density, mie_polarization);
+	atmosphere.mie_scattering = 
+	{
+		mie_scattering,
+		mie_scattering,
+		mie_scattering
+	};
+}
+
+void atmosphere_system::on_atmosphere_construct(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere)
+{
+	update_coefficients(entity);
+}
+
+void atmosphere_system::on_atmosphere_replace(ecs::registry& registry, ecs::entity entity, ecs::atmosphere_component& atmosphere)
+{
+	update_coefficients(entity);
+}
+
+} // namespace ecs

src/ecs/systems/atmosphere-system.hpp

@@ -0,0 +1,53 @@
+/*
+ * 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_ECS_ATMOSPHERE_SYSTEM_HPP
+#define ANTKEEPER_ECS_ATMOSPHERE_SYSTEM_HPP
+
+#include "entity-system.hpp"
+#include "ecs/entity.hpp"
+#include "utility/fundamental-types.hpp"
+#include "ecs/components/atmosphere-component.hpp"
+
+namespace ecs {
+
+/**
+ * Updates variables related to atmospheric scattering.
+ */
+class atmosphere_system:
+	public entity_system
+{
+public:
+	atmosphere_system(ecs::registry& registry);
+	
+	virtual void update(double t, double dt);
+	
+private:
+	void update_coefficients(ecs::entity entity);
+	
+	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);
+	
+	double3 rgb_wavelengths_nm;
+	double3 rgb_wavelengths_m;
+};
+
+} // namespace ecs
+
+#endif // ANTKEEPER_ECS_ATMOSPHERE_SYSTEM_HPP

src/game/bootloader.cpp

@@ -75,6 +75,7 @@
 #include "ecs/systems/painting-system.hpp"
 #include "ecs/systems/astronomy-system.hpp"
 #include "ecs/systems/blackbody-system.hpp"
+#include "ecs/systems/atmosphere-system.hpp"
 #include "ecs/systems/orbit-system.hpp"
 #include "ecs/components/marker-component.hpp"
 #include "ecs/commands.hpp"
@@ -864,6 +865,9 @@ void setup_systems(game_context* ctx)
 	// Setup blackbody system
 	ctx->blackbody_system = new ecs::blackbody_system(*ctx->ecs_registry);
 	
+	// Setup atmosphere system
+	ctx->atmosphere_system = new ecs::atmosphere_system(*ctx->ecs_registry);
+	
 	// Setup astronomy system
 	ctx->astronomy_system = new ecs::astronomy_system(*ctx->ecs_registry);
 	
@@ -1260,6 +1264,7 @@ void setup_callbacks(game_context* ctx)
 			
 			ctx->orbit_system->update(t, dt);
 			ctx->blackbody_system->update(t, dt);
+			ctx->atmosphere_system->update(t, dt);
 			ctx->astronomy_system->update(t, dt);
 			ctx->spatial_system->update(t, dt);
 			ctx->constraint_system->update(t, dt);

src/game/game-context.hpp

@@ -84,6 +84,7 @@ namespace ecs
 	class painting_system;
 	class astronomy_system;
 	class blackbody_system;
+	class atmosphere_system;
 	class orbit_system;
 	class behavior_system;
 	class collision_system;
@@ -249,6 +250,7 @@ struct game_context
 	ecs::tracking_system* tracking_system;
 	ecs::painting_system* painting_system;
 	ecs::blackbody_system* blackbody_system;
+	ecs::atmosphere_system* atmosphere_system;
 	ecs::astronomy_system* astronomy_system;
 	ecs::orbit_system* orbit_system;
 	

src/game/states/play-state.cpp

@@ -112,7 +112,7 @@ void play_state_enter(game_context* ctx)
 		orbit.elements.ta = math::radians(0.0);
 		
 		ecs::blackbody_component blackbody;
-		blackbody.temperature = 5777.0;
+		blackbody.temperature = 5778.0;
 		
 		ecs::transform_component transform;
 		transform.local = math::identity_transform<float>;

src/physics/atmosphere.hpp

@@ -21,6 +21,7 @@
 #define ANTKEEPER_PHYSICS_ATMOSPHERE_HPP
 
 #include "physics/constants.hpp"
+#include "math/constants.hpp"
 #include <cmath>
 
 namespace physics {