add circularize impulse types

src/game.cpp

@@ -139,7 +139,6 @@ getFreeManeuver(GameState* gs)
 	return nullptr;
 }
 
-// TODO: appendManeuver(orbit, node) would be better
 bool
 addManeuver(GameState* gs,
 			GameOrbit* orbit,
@@ -152,7 +151,10 @@ addManeuver(GameState* gs,
 		return false;
 	}
 
-	if (impulse_delta_v == 0.f) {
+	if (impulse_type != ImpulseType::CIRCULARIZE_RAISING
+		&& impulse_type != ImpulseType::CIRCULARIZE_LOWERING
+		&& impulse_delta_v == 0.f)
+	{
 		LOGF(Warning, "refusing to add maneuver with 0 dv\n");
 		return false;
 	}
@@ -172,9 +174,12 @@ addManeuver(GameState* gs,
 	node->impulse_type = impulse_type;
 	// TODO: thrust calculations
 	//double flight_path_angle = orbit->system.sat.gamma;
-	//node.impulse_vector.x = ...
+	//node->impulse_vector.x = ...
 
-	if (node->impulse_type == ImpulseType::PROGRADE) {
+	if (node->impulse_type == ImpulseType::PROGRADE
+		|| node->impulse_type == ImpulseType::CIRCULARIZE_RAISING
+		|| node->impulse_type == ImpulseType::CIRCULARIZE_LOWERING)
+	{
 		node->true_anomaly = true_anomaly;
 		node->impulse_delta_v = impulse_delta_v;
 		node->active = true;
@@ -222,8 +227,16 @@ applyManeuver(GameOrbit* orbit, ManeuverNode* maneuver)
 	TwoBodySystem& sys = orbit->system;
 
 	assert(maneuver);
-	// FIXME: assuming prograde impulse vector
+	// TODO: other impulse types
-	assert(maneuver->impulse_type == ImpulseType::PROGRADE);
+	assert(maneuver->impulse_type == ImpulseType::PROGRADE
+			|| maneuver->impulse_type != ImpulseType::CIRCULARIZE_RAISING
+			|| maneuver->impulse_type != ImpulseType::CIRCULARIZE_LOWERING);
+
+	if (maneuver->impulse_type == ImpulseType::CIRCULARIZE_RAISING) {
+		maneuver->impulse_delta_v = orbitGetCircVelocity(orbit->system);
+	} else if (maneuver->impulse_type == ImpulseType::CIRCULARIZE_LOWERING) {
+		maneuver->impulse_delta_v = orbitGetCircVelocity(orbit->system, false);
+	}
 
 	// re-calculate state vectors at the maneuver node
 	double theta = maneuver->true_anomaly;

src/game.h

@@ -27,6 +27,8 @@ enum struct ImpulseType
 	NONE,
 	PROGRADE,
 	RETROGRADE,
+	CIRCULARIZE_RAISING,
+	CIRCULARIZE_LOWERING,
 	INCLINATION_CHANGE,
 	GENERAL_PLANE_CHANGE,
 	OTHER,
@@ -96,7 +98,7 @@ bool addManeuver(GameState* gs,
 		GameOrbit* orbit,
 		ImpulseType impulse_type,
 		double true_anomaly,
-		double impulse_delta_v);
+		double impulse_delta_v = 0.f);
 
 bool testManeuverStep(ManeuverNode* maneuver,
 		double previous_theta,

src/main.cpp

@@ -251,19 +251,22 @@ loadScene(GameState* gs, RenderState* rs)
 	gs->coord_overlay = addCoordinateOverlay(rs);
 
 	OrbitalElements el1 = orbitInit(8000, 0, 0, 0, 0, DEG2RAD(-90));
-	GameOrbit* go_1 = loadOrbit(gs, rs, body, el1, rg, "sat_01");
+	loadOrbit(gs, rs, body, el1, rg, "sat_01");
+	//GameOrbit* go_1 = loadOrbit(gs, rs, body, el1, rg, "sat_01");
 
 	OrbitalElements el2 = orbitInit(20000, 0, 0, 0, 0, 0);
-	loadOrbit(gs, rs, body, el2, rg, "sat_02");
+	//loadOrbit(gs, rs, body, el2, rg, "sat_02");
-	//GameOrbit* go_2 = loadOrbit(gs, rs, body, el2, rg, "sat_02");
+	GameOrbit* go_2 = loadOrbit(gs, rs, body, el2, rg, "sat_02");
 
+#if 0
 	double v_transfer = orbitGetTransferVelocity(go_1->system, el2);
 	addManeuver(gs, go_1, ImpulseType::PROGRADE, DEG2RAD(180), v_transfer);
-	// FIXME: can't get circularization here unless we simulate the transfer
+	addManeuver(gs, go_1, ImpulseType::CIRCULARIZE_RAISING, DEG2RAD(180));
-	// 	orbit ahead of time, eg) applyManeuver to a dummy orbit
+#else
-	// 	could also add a ImpulseType::CIRCULARIZE and calculate in
+	double v_transfer = orbitGetTransferVelocity(go_2->system, el1);
-	// 	applyManeuver()
+	addManeuver(gs, go_2, ImpulseType::PROGRADE, DEG2RAD(180), v_transfer);
-	addManeuver(gs, go_1, ImpulseType::PROGRADE, DEG2RAD(180), 0.500);
+	addManeuver(gs, go_2, ImpulseType::CIRCULARIZE_LOWERING, DEG2RAD(0));
+#endif
 
 	return true;
 }

src/orbits.cpp

@@ -343,6 +343,17 @@ orbitGetTransferVelocity(const TwoBodySystem& sys,
 	return vt - v1;
 }
 
+double
+orbitGetCircVelocity(const TwoBodySystem& sys, bool raise_apoapse)
+{
+	double r = (raise_apoapse) ? sys.r_apoapsis : sys.r_periapsis;
+	double mu = sys.body.mu;
+	double epsilon_target = orbitGetSpecificEnergy(r, mu);
+	double v = orbitGetVelocity(epsilon_target, mu, r);
+
+	return v - sys.sat.v;
+}
+
 
 // internal
 

src/orbits.h

@@ -258,3 +258,7 @@ orbitGetTimeOfFlight(TwoBodySystem sys, double theta_begin, double theta_end);
 // NOTE return impulse magnitute for Hohmann transfer orbit
 double orbitGetTransferVelocity(const TwoBodySystem& sys,
 	const OrbitalElements& target);
+
+// NOTE: return impulse magnitude for orbit circularization
+double
+orbitGetCircVelocity(const TwoBodySystem& sys, bool raise_apoapse = true);