+Steering::Steering(const Entity &e)
+: entity(e)
+, target_entity(nullptr)
+, target_velocity(0.0f)
+, accel(1.0f)
+, speed(entity.MaxVelocity())
+, wander_radius(1.0f)
+, wander_dist(2.0f)
+, wander_disp(1.0f)
+, wander_pos(1.0f, 0.0f, 0.0f)
+, obstacle_dir(0.0f)
+, enabled(0) {
+
+}
+
+Steering::~Steering() {
+ ClearTargetEntity();
+}
+
+Steering &Steering::SetTargetEntity(Entity &e) noexcept {
+ ClearTargetEntity();
+ target_entity = &e;
+ e.Ref();
+ return *this;
+}
+
+Steering &Steering::ClearTargetEntity() noexcept {
+ if (target_entity) {
+ target_entity->UnRef();
+ target_entity = nullptr;
+ }
+ return *this;
+}
+
+void Steering::Update(World &world, float dt) {
+ if (AnyEnabled(WANDER)) {
+ UpdateWander(world, dt);
+ }
+ if (AnyEnabled(OBSTACLE_AVOIDANCE)) {
+ UpdateObstacle(world);
+ }
+}
+
+void Steering::UpdateWander(World &world, float dt) {
+ glm::vec3 displacement(
+ world.Random().SNorm() * wander_disp,
+ world.Random().SNorm() * wander_disp,
+ world.Random().SNorm() * wander_disp
+ );
+ if (!iszero(displacement)) {
+ wander_pos = normalize(wander_pos + displacement * dt) * wander_radius;
+ }
+}
+
+void Steering::UpdateObstacle(World &world) {
+ if (!entity.Moving()) {
+ obstacle_dir = glm::vec3(0.0f);
+ return;
+ }
+ AABB box(entity.Bounds());
+ box.min.z = -entity.Speed();
+ box.max.z = 0.0f;
+ glm::mat4 transform(find_rotation(glm::vec3(0.0f, 0.0f, -1.0f), entity.Heading()));
+ transform[3] = glm::vec4(entity.Position(), 1.0f);
+ // check if that box intersects with any blocks
+ col.clear();
+ if (!world.Intersection(box, transform, entity.ChunkCoords(), col)) {
+ obstacle_dir = glm::vec3(0.0f);
+ return;
+ }
+ // if so, pick the nearest collision
+ const WorldCollision *nearest = nullptr;
+ glm::vec3 difference(0.0f);
+ float distance = std::numeric_limits<float>::infinity();
+ for (const WorldCollision &c : col) {
+ // diff points from block to state
+ glm::vec3 diff = entity.GetState().RelativePosition(c.ChunkPos()) - c.BlockCoords();
+ float dist = length2(diff);
+ if (dist < distance) {
+ nearest = &c;
+ difference = diff;
+ distance = dist;
+ }
+ }
+ if (!nearest) {
+ // intersection test lied to us
+ obstacle_dir = glm::vec3(0.0f);
+ return;
+ }
+ // and try to avoid it
+ float to_go = dot(difference, entity.Heading());
+ glm::vec3 point(entity.Position() + entity.Heading() * to_go);
+ obstacle_dir = normalize(point - nearest->BlockCoords()) * (entity.Speed() / std::sqrt(distance));
+}
+
+glm::vec3 Steering::Force(const EntityState &state) const noexcept {
+ glm::vec3 force(0.0f);
+ if (!enabled) {
+ return force;
+ }
+ const float max = entity.MaxControlForce();
+ if (AnyEnabled(HALT)) {
+ if (SumForce(force, Halt(state), max)) {
+ return force;
+ }
+ }
+ if (AnyEnabled(TARGET_VELOCITY)) {
+ if (SumForce(force, TargetVelocity(state, target_velocity), max)) {
+ return force;
+ }
+ }
+ if (AnyEnabled(OBSTACLE_AVOIDANCE)) {
+ if (SumForce(force, ObstacleAvoidance(state), max)) {
+ return force;
+ }
+ }
+ if (AnyEnabled(EVADE_TARGET)) {
+ if (HasTargetEntity()) {
+ if (SumForce(force, Evade(state, GetTargetEntity()), max)) {
+ return force;
+ }
+ } else {
+ std::cout << "Steering: evade enabled, but target entity not set" << std::endl;
+ }
+ }
+ if (AnyEnabled(PURSUE_TARGET)) {
+ if (HasTargetEntity()) {
+ if (SumForce(force, Pursuit(state, GetTargetEntity()), max)) {
+ return force;
+ }
+ } else {
+ std::cout << "Steering: pursuit enabled, but target entity not set" << std::endl;
+ }
+ }
+ if (AnyEnabled(WANDER)) {
+ if (SumForce(force, Wander(state), max)) {
+ return force;
+ }
+ }
+ return force;
+}
+
+bool Steering::SumForce(glm::vec3 &out, const glm::vec3 &in, float max) noexcept {
+ if (iszero(in) || any(isnan(in))) {
+ return false;
+ }
+ float current = iszero(out) ? 0.0f : length(out);
+ float remain = max - current;
+ if (remain <= 0.0f) {
+ return true;
+ }
+ float additional = length(in);
+ if (additional > remain) {
+ out += normalize(in) * remain;
+ return true;
+ } else {
+ out += in;
+ return false;
+ }
+}
+
+glm::vec3 Steering::Halt(const EntityState &state) const noexcept {
+ return state.velocity * -accel;
+}
+
+glm::vec3 Steering::TargetVelocity(const EntityState &state, const glm::vec3 &vel) const noexcept {
+ return (vel - state.velocity) * accel;
+}
+
+glm::vec3 Steering::Seek(const EntityState &state, const ExactLocation &loc) const noexcept {
+ const glm::vec3 diff(loc.Difference(state.pos).Absolute());
+ if (iszero(diff)) {
+ return glm::vec3(0.0f);
+ } else {
+ return TargetVelocity(state, normalize(diff) * speed);
+ }
+}
+
+glm::vec3 Steering::Flee(const EntityState &state, const ExactLocation &loc) const noexcept {
+ const glm::vec3 diff(state.pos.Difference(loc).Absolute());
+ if (iszero(diff)) {
+ return glm::vec3(0.0f);
+ } else {
+ return TargetVelocity(state, normalize(diff) * speed);
+ }
+}
+
+glm::vec3 Steering::Arrive(const EntityState &state, const ExactLocation &loc) const noexcept {
+ const glm::vec3 diff(loc.Difference(state.pos).Absolute());
+ const float dist = length(diff);
+ if (dist < std::numeric_limits<float>::epsilon()) {
+ return glm::vec3(0.0f);
+ } else {
+ const float att_speed = std::min(dist * accel, speed);
+ return TargetVelocity(state, diff * att_speed / dist);
+ }
+}
+
+glm::vec3 Steering::Pursuit(const EntityState &state, const Entity &other) const noexcept {
+ const glm::vec3 diff(state.Diff(other.GetState()));
+ if (iszero(diff)) {
+ return TargetVelocity(state, other.Velocity());
+ } else {
+ const float time_estimate = length(diff) / speed;
+ ExactLocation prediction(other.ChunkCoords(), other.Position() + (other.Velocity() * time_estimate));
+ return Seek(state, prediction);
+ }
+}
+
+glm::vec3 Steering::Evade(const EntityState &state, const Entity &other) const noexcept {
+ const glm::vec3 diff(state.Diff(other.GetState()));
+ if (iszero(diff)) {
+ return TargetVelocity(state, -other.Velocity());
+ } else {
+ const float time_estimate = length(diff) / speed;
+ ExactLocation prediction(other.ChunkCoords(), other.Position() + (other.Velocity() * time_estimate));
+ return Flee(state, prediction);
+ }
+}
+
+glm::vec3 Steering::Wander(const EntityState &state) const noexcept {
+ return TargetVelocity(state, normalize(entity.Heading() * wander_dist + wander_pos) * speed);
+}
+
+glm::vec3 Steering::ObstacleAvoidance(const EntityState &state) const noexcept {
+ return obstacle_dir;
+}
+
+