X-Git-Url: http://git.localhorst.tv/?a=blobdiff_plain;f=src%2Fcreature%2Fcreature.cpp;h=690f6fb7fe1608db0045952cce5c648e60ca1dcb;hb=291f8847097107fef4e97c86036e104d97818b8b;hp=ed8551ca49bd1e8330d0336cf0eae885ab97812f;hpb=343b4f7e7cdd53dc1eab7dc32196ae5fa604ba48;p=blobs.git

diff --git a/src/creature/creature.cpp b/src/creature/creature.cpp
index ed8551c..690f6fb 100644
--- a/src/creature/creature.cpp
+++ b/src/creature/creature.cpp
@@ -1,47 +1,245 @@
 #include "Creature.hpp"
-#include "Need.hpp"
+#include "Genome.hpp"
+#include "Memory.hpp"
+#include "NameGenerator.hpp"
+#include "Situation.hpp"
+#include "Steering.hpp"
 
+#include "BlobBackgroundTask.hpp"
+#include "Goal.hpp"
+#include "IdleGoal.hpp"
+#include "InhaleNeed.hpp"
+#include "IngestNeed.hpp"
+#include "Need.hpp"
 #include "../app/Assets.hpp"
+#include "../math/const.hpp"
 #include "../world/Body.hpp"
 #include "../world/Planet.hpp"
+#include "../world/Simulation.hpp"
 #include "../world/TileType.hpp"
 
+#include <algorithm>
+#include <sstream>
 #include <glm/gtx/transform.hpp>
+#include <glm/gtx/vector_angle.hpp>
 
 #include <iostream>
+#include <glm/gtx/io.hpp>
 
 
 namespace blobs {
 namespace creature {
 
-Creature::Creature()
-: body(nullptr)
-, surface(0)
-, position()
+Creature::Creature(world::Simulation &sim)
+: sim(sim)
 , name()
+, genome()
+, properties()
+, cur_prop(0)
+, base_color(1.0)
+, highlight_color(0.0)
+, mass(1.0)
+, density(1.0)
+, size(1.0)
+, birth(sim.Time())
 , health(1.0)
+, on_death()
+, removable(false)
+, memory(*this)
+, bg_task()
 , needs()
+, goals()
+, situation()
+, steering(*this)
 , vao() {
+	// all creatures avoid each other for now
+	steering.Separate(0.1, 1.5);
 }
 
 Creature::~Creature() {
 }
 
+glm::dvec4 Creature::HighlightColor() const noexcept {
+	return glm::dvec4(highlight_color, AgeLerp(CurProps().highlight, NextProps().highlight));
+}
+
+void Creature::Ingest(int res, double amount) noexcept {
+	const Genome::Composition *cmp = nullptr;
+	for (const auto &c : genome.composition) {
+		if (c.resource == res) {
+			cmp = &c;
+			break;
+		}
+	}
+	if (cmp) {
+		const double max_mass = AgeLerp(CurProps().mass, NextProps().mass);
+		Mass(std::min(max_mass, mass + amount));
+	} else {
+		// foreign material. poisonous?
+	}
+}
+
+void Creature::Hurt(double dt) noexcept {
+	health = std::max(0.0, health - dt);
+	if (health == 0.0) {
+		std::cout << "[" << int(sim.Time()) << "s] "
+			<< name << " died" << std::endl;
+		Die();
+	}
+}
+
+void Creature::Die() noexcept {
+	needs.clear();
+	goals.clear();
+	steering.Halt();
+	if (on_death) {
+		on_death(*this);
+	}
+	Remove();
+}
+
+double Creature::Size() const noexcept {
+	return size;
+}
+
+double Creature::Age() const noexcept {
+	return sim.Time() - birth;
+}
+
+std::string Creature::AgeName() const {
+	switch (cur_prop) {
+		case 0:
+			return "Newborn";
+		case 1:
+			return "Child";
+		case 2:
+			return "Youth";
+		case 3:
+			return "Adult";
+		case 4:
+			return "Elder";
+		case 5:
+			return "Dead";
+		default:
+			return "Unknown";
+	}
+}
+
+double Creature::AgeLerp(double from, double to) const noexcept {
+	return glm::mix(from, to, glm::smoothstep(CurProps().age, NextProps().age, Age()));
+}
+
+double Creature::Fertility() const noexcept {
+	return AgeLerp(CurProps().fertility, NextProps().fertility) * (1.0 / 3600.0);
+}
+
+double Creature::Mutability() const noexcept {
+	return GetProperties().mutability * (1.0 / 3600.0);
+}
+
+void Creature::AddGoal(std::unique_ptr<Goal> &&g) {
+	g->Enable();
+	goals.emplace_back(std::move(g));
+}
+
+namespace {
+
+bool GoalCompare(const std::unique_ptr<Goal> &a, const std::unique_ptr<Goal> &b) {
+	return b->Urgency() < a->Urgency();
+}
+
+}
 
 void Creature::Tick(double dt) {
-	for (Need &need : needs) {
-		need.Tick(dt);
-		if (!need.IsSatisfied()) {
-			health = std::max(0.0, health - need.penalty * dt);
+	if (cur_prop < 5 && Age() > NextProps().age) {
+		++cur_prop;
+		if (cur_prop == 5) {
+			std::cout << "[" << int(sim.Time()) << "s] "
+				<< name << " died of old age" << std::endl;
+			Die();
+		} else {
+			std::cout << "[" << int(sim.Time()) << "s] "
+				<< name << " grew up to " << AgeName() << std::endl;
 		}
 	}
+
+	{
+		Situation::State state(situation.GetState());
+		Situation::Derivative a(Step(Situation::Derivative(), 0.0));
+		Situation::Derivative b(Step(a, dt * 0.5));
+		Situation::Derivative c(Step(b, dt * 0.5));
+		Situation::Derivative d(Step(c, dt));
+		Situation::Derivative f(
+			(1.0 / 6.0) * (a.vel + 2.0 * (b.vel + c.vel) + d.vel),
+			(1.0 / 6.0) * (a.acc + 2.0 * (b.acc + c.acc) + d.acc)
+		);
+		state.pos += f.vel * dt;
+		state.vel += f.acc * dt;
+		if (length2(state.vel) > 0.000001) {
+			glm::dvec3 nvel(normalize(state.vel));
+			double ang = angle(nvel, state.dir);
+			double turn_rate = PI * dt;
+			if (ang < turn_rate) {
+				state.dir = normalize(state.vel);
+			} else if (std::abs(ang - PI) < 0.001) {
+				state.dir = rotate(state.dir, turn_rate, world::Planet::SurfaceNormal(situation.Surface()));
+			} else {
+				state.dir = rotate(state.dir, turn_rate, normalize(cross(state.dir, nvel)));
+			}
+		}
+
+		situation.SetState(state);
+	}
+
+	bg_task->Tick(dt);
+	bg_task->Action();
+	memory.Tick(dt);
+	for (auto &need : needs) {
+		need->Tick(dt);
+	}
+	for (auto &goal : goals) {
+		goal->Tick(dt);
+	}
+	// do background stuff
+	for (auto &need : needs) {
+		need->ApplyEffect(*this, dt);
+	}
+	if (goals.empty()) {
+		return;
+	}
+	// if active goal can be interrupted, check priorities
+	if (goals.size() > 1 && goals[0]->Interruptible()) {
+		std::sort(goals.begin(), goals.end(), GoalCompare);
+	}
+	goals[0]->Action();
+	for (auto goal = goals.begin(); goal != goals.end();) {
+		if ((*goal)->Complete()) {
+			goals.erase(goal);
+		} else {
+			++goal;
+		}
+	}
+}
+
+Situation::Derivative Creature::Step(const Situation::Derivative &ds, double dt) const noexcept {
+	Situation::State s = situation.GetState();
+	s.pos += ds.vel * dt;
+	s.vel += ds.acc * dt;
+	return {
+		s.vel,
+		steering.Acceleration(s)
+	};
 }
 
 glm::dmat4 Creature::LocalTransform() noexcept {
 	// TODO: surface transform
-	constexpr double half_height = 0.25;
-	return glm::translate(glm::dvec3(position.x, position.y, position.z + body->Radius() + half_height))
-		* glm::scale(glm::dvec3(half_height, half_height, half_height));
+	const double half_size = size * 0.5;
+	const glm::dvec3 &pos = situation.Position();
+	const glm::dmat3 srf(world::Planet::SurfaceOrientation(situation.Surface()));
+	return glm::translate(glm::dvec3(pos.x, pos.y, pos.z + half_size))
+		* glm::rotate(glm::orientedAngle(-srf[2], situation.Heading(), srf[1]), srf[1])
+		* glm::dmat4(srf)
+		* glm::scale(glm::dvec3(half_size, half_size, half_size));
 }
 
 void Creature::BuildVAO() {
@@ -126,16 +324,16 @@ void Creature::BuildVAO() {
 	vao.Unbind();
 }
 
-void Creature::Draw(app::Assets &assets, graphics::Viewport &viewport) {
+void Creature::Draw(graphics::Viewport &viewport) {
 	vao.Bind();
 	vao.DrawTriangles(6 * 6);
 }
 
 
-void Spawn(Creature &c, world::Planet &p, app::Assets &assets) {
+void Spawn(Creature &c, world::Planet &p) {
 	p.AddCreature(&c);
-	c.Surface(0);
-	c.Position(glm::dvec3(0.0, 0.0, 0.0));
+	c.GetSituation().SetPlanetSurface(p, 0, p.TileCenter(0, p.SideLength() / 2, p.SideLength() / 2));
+	c.GetSituation().Heading(-world::Planet::SurfaceOrientation(0)[2]);
 
 	// probe surrounding area for common resources
 	int start = p.SideLength() / 2 - 2;
@@ -143,7 +341,7 @@ void Spawn(Creature &c, world::Planet &p, app::Assets &assets) {
 	std::map<int, double> yields;
 	for (int y = start; y < end; ++y) {
 		for (int x = start; x < end; ++x) {
-			const world::TileType &t = assets.data.tiles[p.TileAt(0, x, y).type];
+			const world::TileType &t = p.TypeAt(0, x, y);
 			for (auto yield : t.resources) {
 				yields[yield.resource] += yield.ubiquity;
 			}
@@ -152,49 +350,408 @@ void Spawn(Creature &c, world::Planet &p, app::Assets &assets) {
 	int liquid = -1;
 	int solid = -1;
 	for (auto e : yields) {
-		if (assets.data.resources[e.first].state == world::Resource::LIQUID) {
+		if (c.GetSimulation().Resources()[e.first].state == world::Resource::LIQUID) {
 			if (liquid < 0 || e.second > yields[liquid]) {
 				liquid = e.first;
 			}
-		} else if (assets.data.resources[e.first].state == world::Resource::SOLID) {
+		} else if (c.GetSimulation().Resources()[e.first].state == world::Resource::SOLID) {
 			if (solid < 0 || e.second > yields[solid]) {
 				solid = e.first;
 			}
 		}
 	}
 
+	Genome genome;
+
+	genome.properties.Birth().age = { 0.0, 0.0 };
+	genome.properties.Birth().mass = { 0.5, 0.05 };
+	genome.properties.Birth().fertility = { 0.0, 0.0 };
+	genome.properties.Birth().highlight = { 0.0, 0.0 };
+
+	genome.properties.Child().age = { 30.0, 1.0 };
+	genome.properties.Child().mass = { 0.7, 0.05 };
+	genome.properties.Child().fertility = { 0.0, 0.0 };
+	genome.properties.Child().highlight = { 0.2, 0.05 };
+
+	genome.properties.Youth().age = { 60.0, 5.0 };
+	genome.properties.Youth().mass = { 0.9, 0.1 };
+	genome.properties.Youth().fertility = { 0.5, 0.03 };
+	genome.properties.Youth().highlight = { 0.9, 0.1 };
+
+	genome.properties.Adult().age = { 120.0, 10.0 };
+	genome.properties.Adult().mass = { 1.3, 0.1 };
+	genome.properties.Adult().fertility = { 0.4, 0.01 };
+	genome.properties.Adult().highlight = { 0.7, 0.1 };
+
+	genome.properties.Elder().age = { 360.0, 30.0 };
+	genome.properties.Elder().mass = { 1.0, 0.05 };
+	genome.properties.Elder().fertility = { 0.1, 0.01 };
+	genome.properties.Elder().highlight = { 0.6, 0.1 };
+
+	genome.properties.Death().age = { 480.0, 60.0 };
+	genome.properties.Death().mass = { 0.9, 0.05 };
+	genome.properties.Death().fertility = { 0.0, 0.0 };
+	genome.properties.Death().highlight = { 0.5, 0.1 };
+
+	genome.properties.strength = { 1.0, 0.1 };
+	genome.properties.stamina = { 1.0, 0.1 };
+	genome.properties.dexerty = { 1.0, 0.1 };
+	genome.properties.intelligence = { 1.0, 0.1 };
+	genome.properties.mutability = { 1.0, 0.1 };
+
+	glm::dvec3 color_avg(0.0);
+	double color_divisor = 0.0;
+
 	if (p.HasAtmosphere()) {
-		std::cout << "require breathing " << assets.data.resources[p.Atmosphere()].label << std::endl;
-		Need need;
-		need.resource = p.Atmosphere();
-		need.gain = 0.25;
-		need.critical = 0.95;
-		need.penalty = 0.1;
-		c.AddNeed(need);
+		genome.composition.push_back({
+			p.Atmosphere(),    // resource
+			{ 0.01, 0.00001 }, // mass
+			{ 0.5,  0.001 },   // intake
+			{ 0.1,  0.0005 },  // penalty
+			{ 0.0,  0.0 },     // growth
+		});
+		color_avg += c.GetSimulation().Resources()[p.Atmosphere()].base_color * 0.1;
+		color_divisor += 0.1;
 	}
 	if (liquid > -1) {
-		std::cout << "require drinking " << assets.data.resources[liquid].label << std::endl;
-		Need need;
-		need.resource = liquid;
-		need.gain = 0.0001;
-		need.critical = 0.95;
-		need.penalty = 0.01;
-		c.AddNeed(need);
+		genome.composition.push_back({
+			liquid,          // resource
+			{ 0.6,  0.01 },  // mass
+			{ 0.2,  0.001 }, // intake
+			{ 0.01, 0.002 }, // penalty
+			{ 0.1, 0.0 },   // growth
+		});
+		color_avg += c.GetSimulation().Resources()[liquid].base_color * 0.5;
+		color_divisor += 0.5;
 	}
 	if (solid > -1) {
-		std::cout << "require eating " << assets.data.resources[solid].label << std::endl;
-		Need need;
-		need.resource = solid;
-		need.gain = 0.00001;
-		need.critical = 0.95;
-		need.penalty = 0.001;
-		c.AddNeed(need);
+		genome.composition.push_back({
+			solid,             // resource
+			{ 0.4,   0.01 },   // mass
+			{ 0.4,   0.001 },  // intake
+			{ 0.001, 0.0001 }, // penalty
+			{ 10.0,  0.002 },   // growth
+		});
+		color_avg += c.GetSimulation().Resources()[solid].base_color;
+		color_divisor += 1.0;
+	}
+
+	if (color_divisor > 0.001) {
+		color_avg /= color_divisor;
+	}
+	glm::dvec3 hsl = rgb2hsl(color_avg);
+	genome.base_hue = { hsl.x, 0.01 };
+	genome.base_saturation = { hsl.y, 0.01 };
+	genome.base_lightness = { hsl.z, 0.01 };
+
+	genome.Configure(c);
+}
+
+void Genome::Configure(Creature &c) const {
+	c.GetGenome() = *this;
+
+	math::GaloisLFSR &random = c.GetSimulation().Assets().random;
+
+	c.GetProperties() = Instantiate(properties, random);
+
+	double mass = 0.0;
+	double volume = 0.0;
+	for (const auto &comp : composition) {
+		const world::Resource &resource = c.GetSimulation().Resources()[comp.resource];
+		double comp_mass = comp.mass.FakeNormal(random.SNorm());
+		double intake = comp.intake.FakeNormal(random.SNorm());
+		double penalty = comp.penalty.FakeNormal(random.SNorm());
+
+		mass += comp_mass;
+		volume += comp_mass / c.GetSimulation().Resources()[comp.resource].density;
+
+		std::unique_ptr<Need> need;
+		if (resource.state == world::Resource::SOLID) {
+			intake *= std::atan(c.GetProperties().strength);
+			need.reset(new IngestNeed(comp.resource, intake, penalty));
+			need->gain = intake * 0.05;
+		} else if (resource.state == world::Resource::LIQUID) {
+			intake *= std::atan(c.GetProperties().stamina);
+			need.reset(new IngestNeed(comp.resource, intake, penalty));
+			need->gain = intake * 0.1;
+		} else {
+			need.reset(new InhaleNeed(comp.resource, intake, penalty));
+			need->gain = intake * 0.5;
+		}
+		need->name = c.GetSimulation().Resources()[comp.resource].label;
+		need->growth = comp.growth.FakeNormal(random.SNorm());
+		need->value = 0.4;
+		need->inconvenient = 0.5;
+		need->critical = 0.95;
+		c.AddNeed(std::move(need));
+	}
+
+	glm::dvec3 base_color(
+		std::fmod(base_hue.FakeNormal(random.SNorm()) + 1.0, 1.0),
+		glm::clamp(base_saturation.FakeNormal(random.SNorm()), 0.0, 1.0),
+		glm::clamp(base_lightness.FakeNormal(random.SNorm()), 0.0, 1.0)
+	);
+	glm::dvec3 highlight_color(
+		std::fmod(base_color.x + 0.5, 1.0),
+		1.0 - base_color.y,
+		1.0 - base_color.z
+	);
+	c.BaseColor(hsl2rgb(base_color));
+	c.HighlightColor(hsl2rgb(highlight_color));
+
+	c.Mass(c.GetProperties().props[0].mass);
+	c.Density(mass / volume);
+	c.GetSteering().MaxAcceleration(1.4 * std::atan(c.GetProperties().strength));
+	c.GetSteering().MaxSpeed(4.4 * std::atan(c.GetProperties().dexerty));
+	c.SetBackgroundTask(std::unique_ptr<Goal>(new BlobBackgroundTask(c)));
+	c.AddGoal(std::unique_ptr<Goal>(new IdleGoal(c)));
+}
+
+
+void Split(Creature &c) {
+	Creature *a = new Creature(c.GetSimulation());
+	const Situation &s = c.GetSituation();
+	a->Name(c.GetSimulation().Assets().name.Sequential());
+	// TODO: mutate
+	c.GetGenome().Configure(*a);
+	s.GetPlanet().AddCreature(a);
+	// TODO: duplicate situation somehow
+	a->GetSituation().SetPlanetSurface(
+		s.GetPlanet(), s.Surface(),
+		s.Position() + glm::dvec3(0.0, a->Size() * 0.51, 0.0));
+	a->BuildVAO();
+	std::cout << "[" << int(c.GetSimulation().Time()) << "s] "
+		<< a->Name() << " was born" << std::endl;
+
+	Creature *b = new Creature(c.GetSimulation());
+	b->Name(c.GetSimulation().Assets().name.Sequential());
+	c.GetGenome().Configure(*b);
+	s.GetPlanet().AddCreature(b);
+	b->GetSituation().SetPlanetSurface(
+		s.GetPlanet(), s.Surface(),
+		s.Position() + glm::dvec3(0.0, b->Size() * -0.51, 0.0));
+	b->BuildVAO();
+	std::cout << "[" << int(c.GetSimulation().Time()) << "s] "
+		<< b->Name() << " was born" << std::endl;
+
+	c.Die();
+}
+
+
+Memory::Memory(Creature &c)
+: c(c) {
+}
+
+Memory::~Memory() {
+}
+
+void Memory::Tick(double dt) {
+	Situation &s = c.GetSituation();
+	if (s.OnSurface()) {
+		TrackStay({ &s.GetPlanet(), s.Surface(), s.SurfacePosition() }, dt);
+	}
+}
+
+void Memory::TrackStay(const Location &l, double t) {
+	const world::TileType &type = l.planet->TypeAt(l.surface, l.coords.x, l.coords.y);
+	auto entry = known_types.find(type.id);
+	if (entry != known_types.end()) {
+		entry->second.last_been = c.GetSimulation().Time();
+		entry->second.last_loc = l;
+		entry->second.time_spent += t;
+	} else {
+		known_types.emplace(type.id, Stay{
+			c.GetSimulation().Time(),
+			l,
+			c.GetSimulation().Time(),
+			l,
+			t
+		});
 	}
 }
 
 
-void Need::Tick(double dt) noexcept {
-	value = std::min(1.0, value + gain * dt);
+NameGenerator::NameGenerator()
+: counter(0) {
+}
+
+NameGenerator::~NameGenerator() {
+}
+
+std::string NameGenerator::Sequential() {
+	std::stringstream ss;
+	ss << "Blob " << ++counter;
+	return ss.str();
+}
+
+
+Situation::Situation()
+: planet(nullptr)
+, state(glm::dvec3(0.0), glm::dvec3(0.0))
+, surface(0)
+, type(LOST) {
+}
+
+Situation::~Situation() {
+}
+
+bool Situation::OnPlanet() const noexcept {
+	return type == PLANET_SURFACE;
+}
+
+bool Situation::OnSurface() const noexcept {
+	return type == PLANET_SURFACE;
+}
+
+bool Situation::OnTile() const noexcept {
+	glm::ivec2 t(planet->SurfacePosition(surface, state.pos));
+	return type == PLANET_SURFACE
+		&& t.x >= 0 && t.x < planet->SideLength()
+		&& t.y >= 0 && t.y < planet->SideLength();
+}
+
+glm::ivec2 Situation::SurfacePosition() const noexcept {
+	return planet->SurfacePosition(surface, state.pos);
+}
+
+world::Tile &Situation::GetTile() const noexcept {
+	glm::ivec2 t(planet->SurfacePosition(surface, state.pos));
+	return planet->TileAt(surface, t.x, t.y);
+}
+
+const world::TileType &Situation::GetTileType() const noexcept {
+	glm::ivec2 t(planet->SurfacePosition(surface, state.pos));
+	return planet->TypeAt(surface, t.x, t.y);
+}
+
+void Situation::Move(const glm::dvec3 &dp) noexcept {
+	state.pos += dp;
+	if (OnSurface()) {
+		// enforce ground constraint
+		if (Surface() < 3) {
+			state.pos[(Surface() + 2) % 3] = std::max(0.0, state.pos[(Surface() + 2) % 3]);
+		} else {
+			state.pos[(Surface() + 2) % 3] = std::min(0.0, state.pos[(Surface() + 2) % 3]);
+		}
+	}
+}
+
+void Situation::SetPlanetSurface(world::Planet &p, int srf, const glm::dvec3 &pos) noexcept {
+	type = PLANET_SURFACE;
+	planet = &p;
+	surface = srf;
+	state.pos = pos;
+}
+
+
+Steering::Steering(const Creature &c)
+: c(c)
+, target(0.0)
+, haste(0.0)
+, max_accel(1.0)
+, max_speed(1.0)
+, min_dist(0.0)
+, max_look(0.0)
+, separating(false)
+, halting(true)
+, seeking(false)
+, arriving(false) {
+}
+
+Steering::~Steering() {
+}
+
+void Steering::Separate(double min_distance, double max_lookaround) noexcept {
+	separating = true;
+	min_dist = min_distance;
+	max_look = max_lookaround;
+}
+
+void Steering::DontSeparate() noexcept {
+	separating = false;
+}
+
+void Steering::Halt() noexcept {
+	halting = true;
+	seeking = false;
+	arriving = false;
+}
+
+void Steering::Pass(const glm::dvec3 &t) noexcept {
+	target = t;
+	halting = false;
+	seeking = true;
+	arriving = false;
+}
+
+void Steering::GoTo(const glm::dvec3 &t) noexcept {
+	target = t;
+	halting = false;
+	seeking = false;
+	arriving = true;
+}
+
+glm::dvec3 Steering::Acceleration(const Situation::State &s) const noexcept {
+	double speed = max_speed * glm::clamp(max_speed * haste * haste, 0.25, 1.0);
+	double accel = max_speed * glm::clamp(max_accel * haste * haste, 0.5, 1.0);
+	glm::dvec3 result(0.0);
+	if (separating) {
+		// TODO: off surface situation
+		glm::dvec3 repulse(0.0);
+		const Situation &s = c.GetSituation();
+		for (auto &other : s.GetPlanet().Creatures()) {
+			if (&*other == &c) continue;
+			glm::dvec3 diff = s.Position() - other->GetSituation().Position();
+			if (length2(diff) > max_look * max_look) continue;
+			double sep = length(diff) - other->Size() * 0.707 - c.Size() * 0.707;
+			if (sep < min_dist) {
+				repulse += normalize(diff) * (1.0 - sep / min_dist);
+			}
+		}
+		SumForce(result, repulse, accel);
+	}
+	if (halting) {
+		SumForce(result, s.vel * -accel, accel);
+	}
+	if (seeking) {
+		glm::dvec3 diff = target - s.pos;
+		if (!allzero(diff)) {
+			SumForce(result, TargetVelocity(s, (normalize(diff) * speed), accel), accel);
+		}
+	}
+	if (arriving) {
+		glm::dvec3 diff = target - s.pos;
+		double dist = length(diff);
+		if (!allzero(diff) && dist > std::numeric_limits<double>::epsilon()) {
+			SumForce(result, TargetVelocity(s, diff * std::min(dist * accel, speed) / dist, accel), accel);
+		}
+	}
+	return result;
+}
+
+bool Steering::SumForce(glm::dvec3 &out, const glm::dvec3 &in, double max) const noexcept {
+	if (allzero(in) || anynan(in)) {
+		return false;
+	}
+	double cur = allzero(out) ? 0.0 : length(out);
+	double rem = max - 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;
+	}
+}
+
+glm::dvec3 Steering::TargetVelocity(const Situation::State &s, const glm::dvec3 &vel, double acc) const noexcept {
+	return (vel - s.vel) * acc;
 }
 
 }