+Situation::~Situation() {
+}
+
+bool Situation::OnPlanet() const noexcept {
+ return type == PLANET_SURFACE;
+}
+
+bool Situation::OnSurface() const noexcept {
+ return type == PLANET_SURFACE;
+}
+
+world::Tile &Situation::GetTile() const noexcept {
+ double side_length = planet->SideLength();
+ double offset = side_length * 0.5;
+ double x = std::max(0.0, std::min(side_length, position.x + offset));
+ double y = std::max(0.0, std::min(side_length, position.y + offset));
+ return planet->TileAt(surface, int(x), int(y));
+}
+
+const world::TileType &Situation::GetTileType() const noexcept {
+ return planet->GetSimulation().TileTypes()[GetTile().type];
+}
+
+void Situation::Move(const glm::dvec3 &dp) noexcept {
+ position += dp;
+ if (OnSurface()) {
+ // enforce ground constraint
+ position.z = std::max(0.0, position.z);
+ }
+}
+
+void Situation::SetPlanetSurface(world::Planet &p, int srf, const glm::dvec3 &pos) noexcept {
+ type = PLANET_SURFACE;
+ planet = &p;
+ surface = srf;
+ position = pos;
+}
+
+
+Steering::Steering()
+: seek_target(0.0)
+, max_accel(1.0)
+, max_speed(1.0)
+, halting(false)
+, seeking(false) {
+}
+
+Steering::~Steering() {
+}
+
+void Steering::Halt() noexcept {
+ halting = true;
+ seeking = false;
+}
+
+void Steering::GoTo(const glm::dvec3 &t) noexcept {
+ seek_target = t;
+ halting = false;
+ seeking = true;
+}
+
+glm::dvec3 Steering::Acceleration(Creature &c) const noexcept {
+ glm::dvec3 acc(0.0);
+ if (halting) {
+ SumForce(acc, c.Velocity() * -max_accel);
+ }
+ if (seeking) {
+ glm::dvec3 diff = seek_target - c.GetSituation().Position();
+ if (!allzero(diff)) {
+ SumForce(acc, ((normalize(diff) * max_speed) - c.Velocity()) * max_accel);
+ }
+ }
+ return acc;
+}
+
+bool Steering::SumForce(glm::dvec3 &out, const glm::dvec3 &in) const noexcept {
+ if (allzero(in) || anynan(in)) {
+ return false;
+ }
+ double cur = allzero(out) ? 0.0 : length(out);
+ double rem = max_accel - cur;
+ if (rem < 0.0) {
+ return true;
+ }
+ double add = length(in);
+ if (add > rem) {
+ // this method is off if in and out are in different
+ // directions, but gives okayish results
+ out += in * (1.0 / add);
+ return true;
+ } else {
+ out += in;
+ return false;
+ }