Add function for converting visual magnitude to relative brightness. Pass relative brightness to star geometry

src/astro/illuminance.cpp

@@ -23,6 +23,13 @@
 namespace astro
 {
 
+double vmag_to_brightness(double mv)
+{
+	// 100^(1/5)
+	static constexpr double fifth_root_100 = 2.5118864315095801110850320677993;
+	return std::pow(fifth_root_100, -mv);
+}
+
 double vmag_to_lux(double mv)
 {
 	return std::pow(10.0, (-14.18 - mv) * 0.4);

src/astro/illuminance.hpp

@@ -22,6 +22,17 @@
 
 namespace astro
 {
+	
+	
+/**
+ * Converts apparent (visual) magnitude to a brightness factor relative to a 0th magnitude star.
+ *
+ * @param mv Illuminance in apparent magnitude.
+ * @return Relative brightness factor.
+ *
+ * @see https://en.wikipedia.org/wiki/Illuminance
+ */
+double vmag_to_brightness(double mv);
 
 /**
  * Converts apparent (visual) magnitude to lux.

src/game/state/nuptial-flight.cpp

@@ -114,11 +114,6 @@ nuptial_flight::nuptial_flight(game::context& ctx):
 	
 	// Setup camera
 	setup_camera();
-	/*
-	ctx.surface_camera->look_at({0, 0, 1}, {0, 0, 0}, {0, 1, 0});
-	ctx.surface_camera->set_exposure(-14.5f);
-	ctx.surface_scene->update_tweens();
-	*/
 	
 	// Queue fade in
 	ctx.fade_transition_color->set_value({1, 1, 1});
@@ -252,6 +247,7 @@ void nuptial_flight::enable_controls()
 	bool gamepad_invert_pan = false;
 	bool mouse_look_toggle = false;
 	ctx.mouse_look = false;
+	const double time_scale = 5000.0;
 	
 	if (ctx.config->contains("mouse_tilt_sensitivity"))
 		mouse_tilt_sensitivity = math::radians((*ctx.config)["mouse_tilt_sensitivity"].get<float>());
@@ -542,6 +538,36 @@ void nuptial_flight::enable_controls()
 	);
 	*/
 	
+	// Fast-forward
+	ctx.controls["fast_forward"]->set_activated_callback
+	(
+		[&ctx = this->ctx, time_scale]()
+		{
+			game::world::set_time_scale(ctx, time_scale);
+		}
+	);
+	ctx.controls["fast_forward"]->set_deactivated_callback
+	(
+		[&ctx = this->ctx, time_scale]()
+		{
+			game::world::set_time_scale(ctx, 0.0);
+		}
+	);
+	ctx.controls["rewind"]->set_activated_callback
+	(
+		[&ctx = this->ctx, time_scale]()
+		{
+			game::world::set_time_scale(ctx, -time_scale);
+		}
+	);
+	ctx.controls["rewind"]->set_deactivated_callback
+	(
+		[&ctx = this->ctx, time_scale]()
+		{
+			game::world::set_time_scale(ctx, 0.0);
+		}
+	);
+	
 	// Setup pause control
 	ctx.controls["pause"]->set_activated_callback
 	(

src/game/world.cpp

@@ -38,6 +38,7 @@
 #include "gl/vertex-buffer.hpp"
 #include "physics/light/photometry.hpp"
 #include "physics/orbit/orbit.hpp"
+#include "astro/illuminance.hpp"
 #include "render/material.hpp"
 #include "render/model.hpp"
 #include "render/passes/shadow-map-pass.hpp"
@@ -110,14 +111,11 @@ void create_stars(game::context& ctx)
 		// Transform XYZ color to ACEScg colorspace
 		double3 color_acescg = color::xyz::to_acescg(color_xyz);
 		
-		// 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
-		double vmag_illuminance = vmag_irradiance * (683.0 * 0.14);
+		// Convert apparent magnitude to brightness factor relative to a 0th magnitude star
+		double brightness = astro::vmag_to_brightness(vmag);
 		
-		// Scale color by illuminance
-		double3 scaled_color = color_acescg * vmag_illuminance;
+		// Scale color by relative brightness
+		double3 scaled_color = color_acescg * brightness;
 		
 		// Build vertex
 		*(star_vertex++) = static_cast<float>(position_inertial.x);
@@ -126,7 +124,7 @@ void create_stars(game::context& ctx)
 		*(star_vertex++) = static_cast<float>(scaled_color.x);
 		*(star_vertex++) = static_cast<float>(scaled_color.y);
 		*(star_vertex++) = static_cast<float>(scaled_color.z);
-		*(star_vertex++) = static_cast<float>(vmag);
+		*(star_vertex++) = static_cast<float>(brightness);
 	}
 	
 	// Unload star catalog