add time of flight info to gooey

src/gooey.cpp

@@ -152,6 +152,12 @@ void drawSystemWindow(system_2body& sys)
 		ImGui::Text("h, angular momentum:        %f", sys.h);
 		ImGui::Text("r_apoapsis:                 %f", sys.r_apoapsis);
 		ImGui::Text("r_periapsis:                %f", sys.r_periapsis);
+		// FIXME: not ideal to call into orbit interface from the gooey
+		double tof_apoapse = orbitGetTimeOfFlight(sys, sys.sat.theta, M_PI);
+		ImGui::Text("time to apoapsis:	  %.2f seconds", tof_apoapse);
+		double tof_periapse =
+			orbitGetTimeOfFlight(sys, sys.sat.theta, 2 * M_PI);
+		ImGui::Text("time to periapsis:	  %.2f seconds", tof_periapse);
 		ImGui::Dummy(V_SPACER);
 	}
 }