3 files changed, 18 insertions, 0 deletions
diff --git a/lib/chronology.cpp b/lib/chronology.cpp
new file mode 100644
index 0000000..8707bba
--- /dev/null
+++ b/lib/chronology.cpp
@@ -0,0 +1,12 @@
+#include "chronology.h"
+
+time_t
+operator""_time_t(const char * iso, size_t)
+{
+	struct tm tm {};
+
+	if (const auto end = strptime(iso, "%FT%T", &tm); !end || *end) {
+		throw std::invalid_argument("Invalid date");
+	}
+	return mktime(&tm);
+}
diff --git a/lib/chronology.h b/lib/chronology.h
index 1980116..688a1f7 100644
--- a/lib/chronology.h
+++ b/lib/chronology.h
@@ -1,5 +1,7 @@
 #pragma once
 
 #include <chrono>
+#include <ctime>
 
 using TickDuration = std::chrono::duration<float, std::chrono::seconds::period>;
+time_t operator""_time_t(const char * iso, size_t);
diff --git a/lib/maths.h b/lib/maths.h
index 018ef0e..3127d3c 100644
--- a/lib/maths.h
+++ b/lib/maths.h
@@ -42,6 +42,10 @@ constexpr auto half_pi {glm::half_pi<float>()};
 constexpr auto quarter_pi {half_pi / 2};
 constexpr auto pi {glm::pi<float>()};
 constexpr auto two_pi {glm::two_pi<float>()};
+constexpr auto degreesToRads = pi / 180.F;
+
+constexpr auto earthMeanRadius = 6371.01F; // In km
+constexpr auto astronomicalUnit = 149597890.F; // In km
 
 template<glm::length_t D>
 constexpr inline GlobalPosition<D>