From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Sat, 25 Nov 2017 12:11:19 +0000 (+0100)
Subject: little better seek ai
X-Git-Url: http://git.localhorst.tv/?p=blobs.git;a=commitdiff_plain;h=3b0a4ba59825b2d6a47e9d997736742edf55240c

little better seek ai
---

diff --git a/src/app/app.cpp b/src/app/app.cpp
index b4ede47..e4dc1a5 100644
--- a/src/app/app.cpp
+++ b/src/app/app.cpp
@@ -211,6 +211,7 @@ Assets::Assets()
 	LoadTileTexture("tundra",   textures.tiles, 11);
 	LoadTileTexture("water",    textures.tiles, 12);
 	LoadTileTexture("wheat",    textures.tiles, 13);
+	textures.tiles.FilterTrilinear();
 
 	textures.skins.Bind();
 	textures.skins.Reserve(256, 256, 9, format);
@@ -223,6 +224,7 @@ Assets::Assets()
 	LoadSkinTexture("7", textures.skins, 6);
 	LoadSkinTexture("8", textures.skins, 7);
 	LoadSkinTexture("9", textures.skins, 8);
+	textures.skins.FilterTrilinear();
 }
 
 Assets::~Assets() {
diff --git a/src/blobs.cpp b/src/blobs.cpp
index 18e62aa..006644b 100644
--- a/src/blobs.cpp
+++ b/src/blobs.cpp
@@ -67,7 +67,7 @@ int main(int argc, char *argv[]) {
 	std::cout << "moon cycle in days: " << (moon.OrbitalPeriod() / planet.RotationalPeriod()) << std::endl;
 	std::cout << "moon cycles per year: " << (planet.OrbitalPeriod() / moon.OrbitalPeriod()) << std::endl;
 
-	auto blob = new creature::Creature;
+	auto blob = new creature::Creature(sim);
 	Spawn(*blob, planet, assets);
 	blob->BuildVAO();
 	blob->Name("Blob");
@@ -80,7 +80,7 @@ int main(int argc, char *argv[]) {
 		// sunset
 		//.FirstPerson(3, glm::vec3(0.0f, 0.0f, 0.1f), glm::vec3(1.0f, -0.75f, 0.1f))
 		// from afar
-		.MapView(0, glm::vec3(0.0f, 0.0f, 30.0f), 0.0f)
+		.MapView(0, glm::vec3(0.0f, 0.0f, 31.0f), 0.0f)
 		// from afar, rotating
 		//.Orbital(glm::vec3(-60.0f, 0.0f, 0.0f))
 	;
diff --git a/src/creature/Creature.hpp b/src/creature/Creature.hpp
index aaeb6cf..ce56dfb 100644
--- a/src/creature/Creature.hpp
+++ b/src/creature/Creature.hpp
@@ -23,13 +23,14 @@ namespace graphics {
 namespace world {
 	class Body;
 	class Planet;
+	class Simulation;
 }
 namespace creature {
 
 class Creature {
 
 public:
-	Creature();
+	explicit Creature(world::Simulation &);
 	~Creature();
 
 	Creature(const Creature &) = delete;
@@ -39,9 +40,15 @@ public:
 	Creature &operator =(Creature &&) = delete;
 
 public:
+	world::Simulation &GetSimulation() noexcept { return sim; }
+	const world::Simulation &GetSimulation() const noexcept { return sim; }
+
 	void Name(const std::string &n) noexcept { name = n; }
 	const std::string &Name() const noexcept { return name; }
 
+	void Size(double s) noexcept { size = s; }
+	double Size() const noexcept { return size; }
+
 	void Health(double h) noexcept { health = h; }
 	double Health() const noexcept { return health; }
 	void Hurt(double d) noexcept;
@@ -62,6 +69,7 @@ public:
 
 	void Velocity(const glm::dvec3 &v) noexcept { vel = v; }
 	const glm::dvec3 &Velocity() const noexcept { return vel; }
+	bool Moving() const noexcept { return !allzero(vel); }
 
 	glm::dmat4 LocalTransform() noexcept;
 
@@ -69,7 +77,9 @@ public:
 	void Draw(app::Assets &, graphics::Viewport &);
 
 private:
+	world::Simulation &sim;
 	std::string name;
+	double size;
 	double health;
 
 	std::vector<std::unique_ptr<Need>> needs;
diff --git a/src/creature/Goal.hpp b/src/creature/Goal.hpp
index d664e6b..2ec03bf 100644
--- a/src/creature/Goal.hpp
+++ b/src/creature/Goal.hpp
@@ -1,18 +1,34 @@
 #ifndef BLOBS_CREATURE_GOAL_HPP_
 #define BLOBS_CREATURE_GOAL_HPP_
 
+#include <functional>
+#include <string>
+
+
 namespace blobs {
 namespace creature {
 
 class Creature;
+class Situation;
+class Steering;
 
 class Goal {
 
 public:
-	Goal();
+	using Callback = std::function<void(Goal &)>;
+
+public:
+	explicit Goal(Creature &);
 	virtual ~Goal() noexcept;
 
 public:
+	Creature &GetCreature() noexcept { return c; }
+	const Creature &GetCreature() const noexcept { return c; }
+	Situation &GetSituation() noexcept;
+	const Situation &GetSituation() const noexcept;
+	Steering &GetSteering() noexcept;
+	const Steering &GetSteering() const noexcept;
+
 	double Urgency() const noexcept { return urgency; }
 	void Urgency(double u) noexcept { urgency = u; }
 
@@ -20,14 +36,19 @@ public:
 	void Interruptible(bool i) noexcept { interruptible = i; }
 
 	bool Complete() const noexcept { return complete; }
-	void Complete(bool i) noexcept { complete = i; }
+	void SetComplete() noexcept;
+	/// only supports one callback for now, new one will replace an old
+	void OnComplete(Callback) noexcept;
 
 public:
-	virtual void Enable(Creature &) { }
+	virtual std::string Describe() const = 0;
+	virtual void Enable() { }
 	virtual void Tick(double dt) { }
-	virtual void Action(Creature &) { }
+	virtual void Action() { }
 
 private:
+	Creature &c;
+	Callback on_complete;
 	double urgency;
 	bool interruptible;
 	bool complete;
diff --git a/src/creature/IngestNeed.hpp b/src/creature/IngestNeed.hpp
index 4244293..b0262b8 100644
--- a/src/creature/IngestNeed.hpp
+++ b/src/creature/IngestNeed.hpp
@@ -7,7 +7,7 @@
 namespace blobs {
 namespace creature {
 
-class Need;
+class Goal;
 
 class IngestNeed
 : public Need {
@@ -20,11 +20,14 @@ public:
 	void ApplyEffect(Creature &, double dt) override;
 
 private:
+	void OnLocateComplete(Goal &);
+
+private:
+	Goal *locate_goal;
 	int resource;
 	double speed;
 	double damage;
 	bool ingesting;
-	bool locating;
 
 };
 
diff --git a/src/creature/LocateResourceGoal.hpp b/src/creature/LocateResourceGoal.hpp
index b5d390c..afa5b93 100644
--- a/src/creature/LocateResourceGoal.hpp
+++ b/src/creature/LocateResourceGoal.hpp
@@ -1,6 +1,9 @@
 #ifndef BLOBS_CREATURE_LOCATERESOURCEGOAL_HPP_
 #define BLOBS_CREATURE_LOCATERESOURCEGOAL_HPP_
 
+#include "../graphics/glm.hpp"
+
+
 namespace blobs {
 namespace creature {
 
@@ -8,16 +11,26 @@ class LocateResourceGoal
 : public Goal {
 
 public:
-	explicit LocateResourceGoal(int resource);
+	LocateResourceGoal(Creature &, int resource);
 	~LocateResourceGoal() noexcept override;
 
 public:
-	void Enable(Creature &) override;
+	std::string Describe() const override;
+	void Enable() override;
 	void Tick(double dt) override;
-	void Action(Creature &) override;
+	void Action() override;
+
+private:
+	void LocateResource();
+	void SearchVicinity();
+	bool OnTargetTile() const noexcept;
 
 private:
 	int res;
+	bool found;
+	glm::dvec3 target_pos;
+	int target_srf;
+	glm::ivec2 target_tile;
 
 };
 
diff --git a/src/creature/creature.cpp b/src/creature/creature.cpp
index 1278e26..043aed7 100644
--- a/src/creature/creature.cpp
+++ b/src/creature/creature.cpp
@@ -16,13 +16,16 @@
 #include <glm/gtx/transform.hpp>
 
 #include <iostream>
+#include <glm/gtx/io.hpp>
 
 
 namespace blobs {
 namespace creature {
 
-Creature::Creature()
-: name()
+Creature::Creature(world::Simulation &sim)
+: sim(sim)
+, name()
+, size(1.0)
 , health(1.0)
 , needs()
 , goals()
@@ -40,7 +43,8 @@ void Creature::Hurt(double dt) noexcept {
 }
 
 void Creature::AddGoal(std::unique_ptr<Goal> &&g) {
-	g->Enable(*this);
+	std::cout << "new goal: " << g->Describe() << std::endl;
+	g->Enable();
 	goals.emplace_back(std::move(g));
 }
 
@@ -73,11 +77,18 @@ void Creature::Tick(double dt) {
 	}
 	// if active goal can be interrupted, check priorities
 	if (goals.size() > 1 && goals[0]->Interruptible()) {
+		Goal *old_top = &*goals[0];
 		std::sort(goals.begin(), goals.end(), GoalCompare);
+		Goal *new_top = &*goals[0];
+		if (new_top != old_top) {
+			std::cout << "changing goal from " << old_top->Describe()
+				<< " to " << new_top->Describe() << std::endl;
+		}
 	}
-	goals[0]->Action(*this);
+	goals[0]->Action();
 	for (auto goal = goals.begin(); goal != goals.end();) {
 		if ((*goal)->Complete()) {
+			std::cout << "complete goal: " << (*goal)->Describe() << std::endl;
 			goals.erase(goal);
 		} else {
 			++goal;
@@ -87,10 +98,10 @@ void Creature::Tick(double dt) {
 
 glm::dmat4 Creature::LocalTransform() noexcept {
 	// TODO: surface transform
-	constexpr double half_height = 0.25;
+	const double half_size = size * 0.5;
 	const glm::dvec3 &pos = situation.Position();
-	return glm::translate(glm::dvec3(pos.x, pos.y, pos.z + situation.GetPlanet().Radius() + half_height))
-		* glm::scale(glm::dvec3(half_height, half_height, half_height));
+	return glm::translate(glm::dvec3(pos.x, pos.y, pos.z + half_size))
+		* glm::scale(glm::dvec3(half_size, half_size, half_size));
 }
 
 void Creature::BuildVAO() {
@@ -183,7 +194,8 @@ void Creature::Draw(app::Assets &assets, graphics::Viewport &viewport) {
 
 void Spawn(Creature &c, world::Planet &p, app::Assets &assets) {
 	p.AddCreature(&c);
-	c.GetSituation().SetPlanetSurface(p, 0, glm::dvec3(0.0, 0.0, 0.0));
+	c.GetSituation().SetPlanetSurface(p, 0, p.TileCenter(0, p.SideLength() / 2, p.SideLength() / 2));
+	c.Size(0.5);
 
 	// probe surrounding area for common resources
 	int start = p.SideLength() / 2 - 2;
@@ -224,7 +236,7 @@ void Spawn(Creature &c, world::Planet &p, app::Assets &assets) {
 		std::cout << "require drinking " << assets.data.resources[liquid].label << std::endl;
 		std::unique_ptr<Need> need(new IngestNeed(liquid, 0.2, 0.01));
 		need->name = assets.data.resources[liquid].label;
-		need->gain = 0.01;
+		need->gain = 0.02;
 		need->inconvenient = 0.6;
 		need->critical = 0.95;
 		c.AddNeed(std::move(need));
@@ -233,7 +245,7 @@ void Spawn(Creature &c, world::Planet &p, app::Assets &assets) {
 		std::cout << "require eating " << assets.data.resources[solid].label << std::endl;
 		std::unique_ptr<Need> need(new IngestNeed(solid, 0.1, 0.001));
 		need->name = assets.data.resources[solid].label;
-		need->gain = 0.007;
+		need->gain = 0.017;
 		need->inconvenient = 0.6;
 		need->critical = 0.95;
 		c.AddNeed(std::move(need));
@@ -274,7 +286,11 @@ void Situation::Move(const glm::dvec3 &dp) noexcept {
 	position += dp;
 	if (OnSurface()) {
 		// enforce ground constraint
-		position.z = std::max(0.0, position.z);
+		if (Surface() < 3) {
+			position[(Surface() + 2) % 3] = std::max(0.0, position[(Surface() + 2) % 3]);
+		} else {
+			position[(Surface() + 2) % 3] = std::min(0.0, position[(Surface() + 2) % 3]);
+		}
 	}
 }
 
diff --git a/src/creature/goal.cpp b/src/creature/goal.cpp
index 1b9d5d0..18714e4 100644
--- a/src/creature/goal.cpp
+++ b/src/creature/goal.cpp
@@ -3,13 +3,21 @@
 
 #include "Creature.hpp"
 #include "../world/Planet.hpp"
+#include "../world/Resource.hpp"
+#include "../world/Simulation.hpp"
 #include "../world/TileType.hpp"
 
+#include <iostream>
+#include <glm/gtx/io.hpp>
+
+
 namespace blobs {
 namespace creature {
 
-Goal::Goal()
-: urgency(0.0)
+Goal::Goal(Creature &c)
+: c(c)
+, on_complete()
+, urgency(0.0)
 , interruptible(true)
 , complete(false) {
 }
@@ -17,68 +25,145 @@ Goal::Goal()
 Goal::~Goal() noexcept {
 }
 
+Situation &Goal::GetSituation() noexcept {
+	return c.GetSituation();
+}
+
+const Situation &Goal::GetSituation() const noexcept {
+	return c.GetSituation();
+}
+
+Steering &Goal::GetSteering() noexcept {
+	return c.GetSteering();
+}
 
-LocateResourceGoal::LocateResourceGoal(int res)
-: res(res) {
+const Steering &Goal::GetSteering() const noexcept {
+	return c.GetSteering();
+}
+
+void Goal::SetComplete() noexcept {
+	if (!complete) {
+		complete = true;
+		if (on_complete) {
+			on_complete(*this);
+		}
+	}
+}
+
+void Goal::OnComplete(std::function<void(Goal &)> cb) noexcept {
+	on_complete = cb;
+	if (complete) {
+		on_complete(*this);
+	}
+}
+
+
+LocateResourceGoal::LocateResourceGoal(Creature &c, int res)
+: Goal(c)
+, res(res)
+, found(false)
+, target_pos(0.0)
+, target_srf(0)
+, target_tile(0) {
 }
 
 LocateResourceGoal::~LocateResourceGoal() noexcept {
 }
 
-void LocateResourceGoal::Enable(Creature &c) {
+std::string LocateResourceGoal::Describe() const {
+	return "locate " + GetCreature().GetSimulation().Resources()[res].name;
+}
+
+void LocateResourceGoal::Enable() {
+	LocateResource();
 }
 
 void LocateResourceGoal::Tick(double dt) {
 }
 
-void LocateResourceGoal::Action(Creature &c) {
-	if (c.GetSituation().OnSurface()) {
-		const world::TileType &t = c.GetSituation().GetTileType();
+void LocateResourceGoal::Action() {
+	if (!found) {
+		LocateResource();
+	} else if (OnTargetTile()) {
+		GetSteering().Halt();
+		if (!GetCreature().Moving()) {
+			SetComplete();
+		}
+	} else {
+		GetSteering().GoTo(target_pos);
+	}
+}
+
+void LocateResourceGoal::LocateResource() {
+	if (GetSituation().OnSurface()) {
+		const world::TileType &t = GetSituation().GetTileType();
 		auto yield = t.FindResource(res);
 		if (yield != t.resources.cend()) {
 			// hoooray
-			c.GetSteering().Halt();
-			Complete(true);
+			GetSteering().Halt();
+			found = true;
+			target_pos = GetSituation().Position();
+			target_srf = GetSituation().Surface();
+			target_tile = GetSituation().GetPlanet().SurfacePosition(target_srf, target_pos);
 		} else {
 			// go find somewhere else
-			const world::Planet &planet = c.GetSituation().GetPlanet();
-			double side_length = planet.SideLength();
-			double offset = side_length * 0.5;
-			glm::ivec2 loc = glm::ivec2(c.GetSituation().Position() + offset);
-			glm::ivec2 seek_radius(2);
-			glm::ivec2 begin(glm::max(glm::ivec2(0), loc - seek_radius));
-			glm::ivec2 end(glm::min(glm::ivec2(side_length), loc + seek_radius));
-			const world::TileType::Yield *best = nullptr;
-			glm::ivec2 best_pos;
-			double best_distance = 2 * side_length * side_length;
-			for (int y = begin.y; y < end.y; ++y) {
-				for (int x = begin.x; x < end.x; ++x) {
-					const world::TileType &type = planet.TypeAt(c.GetSituation().Surface(), x, y);
-					auto yield = type.FindResource(res);
-					if (yield != type.resources.cend()) {
-						double dist = glm::length2(glm::dvec3(x - offset + 0.5, y - offset + 0.5, 0.0) - c.GetSituation().Position());
-						if (!best) {
-							best = &*yield;
-							best_pos = glm::ivec2(x, y);
-							best_distance = dist;
-						} else if (yield->ubiquity + (dist * 0.125) > best->ubiquity + (best_distance * 0.125)) {
-							best = &*yield;
-							best_pos = glm::ivec2(x, y);
-							best_distance = dist;
-						}
-					}
+			SearchVicinity();
+		}
+	} else {
+		// well, what now?
+	}
+}
+
+void LocateResourceGoal::SearchVicinity() {
+	const world::Planet &planet = GetSituation().GetPlanet();
+	int srf = GetSituation().Surface();
+	const glm::dvec3 &pos = GetSituation().Position();
+
+	glm::ivec2 loc = planet.SurfacePosition(srf, pos);
+	glm::ivec2 seek_radius(2);
+	glm::ivec2 begin(glm::max(glm::ivec2(0), loc - seek_radius));
+	glm::ivec2 end(glm::min(glm::ivec2(planet.SideLength()), loc + seek_radius));
+
+	const world::TileType::Yield *best = nullptr;
+	glm::ivec2 best_pos;
+	double best_distance;
+
+	for (int y = begin.y; y < end.y; ++y) {
+		for (int x = begin.x; x < end.x; ++x) {
+			const world::TileType &type = planet.TypeAt(srf, x, y);
+			auto yield = type.FindResource(res);
+			if (yield != type.resources.cend()) {
+				double dist = glm::length2(planet.TileCenter(srf, x, y) - pos);
+				if (!best) {
+					best = &*yield;
+					best_pos = glm::ivec2(x, y);
+					best_distance = dist;
+				} else if (yield->ubiquity - (dist * 0.125) > best->ubiquity - (best_distance * 0.125)) {
+					best = &*yield;
+					best_pos = glm::ivec2(x, y);
+					best_distance = dist;
 				}
 			}
-			if (best) {
-				c.GetSteering().GoTo(glm::dvec3(best_pos.x - offset + 0.5, best_pos.y - offset + 0.5, 0.0));
-			} else {
-				// oh crap
-			}
 		}
+	}
+	if (best) {
+		found = true;
+		target_pos = planet.TileCenter(srf, best_pos.x, best_pos.y);
+		target_srf = srf;
+		target_tile = best_pos;
+		GetSteering().GoTo(target_pos);
+		std::cout << "found resource at " << target_pos << std::endl;
 	} else {
-		// well, what now?
+		// oh crap
 	}
 }
 
+bool LocateResourceGoal::OnTargetTile() const noexcept {
+	const Situation &s = GetSituation();
+	return s.OnSurface()
+		&& s.Surface() == target_srf
+		&& s.GetPlanet().SurfacePosition(s.Surface(), s.Position()) == target_tile;
+}
+
 }
 }
diff --git a/src/creature/need.cpp b/src/creature/need.cpp
index 60e7cb8..64ebf5b 100644
--- a/src/creature/need.cpp
+++ b/src/creature/need.cpp
@@ -28,11 +28,11 @@ void Need::Decrease(double delta) noexcept {
 
 
 IngestNeed::IngestNeed(int resource, double speed, double damage)
-: resource(resource)
+: locate_goal(nullptr)
+, resource(resource)
 , speed(speed)
 , damage(damage)
-, ingesting(false)
-, locating(false) {
+, ingesting(false) {
 }
 
 IngestNeed::~IngestNeed() {
@@ -53,20 +53,33 @@ void IngestNeed::ApplyEffect(Creature &c, double dt) {
 					Decrease(std::min(yield.ubiquity, speed) * dt);
 					if (value == 0.0) {
 						ingesting = false;
-						locating = false;
+						if (locate_goal) {
+							// abort
+							locate_goal->Complete();
+						}
 					}
 					break;
 				}
 			}
-			if (!found && !locating) {
-				c.AddGoal(std::unique_ptr<Goal>(new LocateResourceGoal(resource)));
-				locating = true;
+			if (!found && !locate_goal) {
+				locate_goal = new LocateResourceGoal(c, resource);
+				locate_goal->OnComplete([&](Goal &g){ OnLocateComplete(g); });
+				c.AddGoal(std::unique_ptr<Goal>(locate_goal));
 			}
 		}
 	}
 	if (IsCritical()) {
 		c.Hurt(damage * dt);
 	}
+	if (locate_goal) {
+		locate_goal->Urgency(value);
+	}
+}
+
+void IngestNeed::OnLocateComplete(Goal &g) {
+	if (&g == locate_goal) {
+		locate_goal = nullptr;
+	}
 }
 
 
diff --git a/src/graphics/shader.cpp b/src/graphics/shader.cpp
index c63a280..1b641b0 100644
--- a/src/graphics/shader.cpp
+++ b/src/graphics/shader.cpp
@@ -227,7 +227,7 @@ PlanetSurface::PlanetSurface()
 
 		"void main() {\n"
 			"vec3 tex_color = texture(tex_sampler, frag_tex_uv).rgb;\n"
-			"vec3 total_light = tex_color * vec3(0.01, 0.01, 0.01);\n"
+			"vec3 total_light = tex_color * vec3(0.1, 0.1, 0.1);\n"
 			"for (int i = 0; i < num_lights; ++i) {\n"
 				"vec3 to_light = light[i].position - vtx_viewspace;\n"
 				"float distance = length(to_light) + length(vtx_viewspace);\n"
diff --git a/src/world/Planet.hpp b/src/world/Planet.hpp
index 8cd9efe..2274d04 100644
--- a/src/world/Planet.hpp
+++ b/src/world/Planet.hpp
@@ -9,6 +9,7 @@
 #include "../graphics/SimpleVAO.hpp"
 
 #include <cassert>
+#include <memory>
 #include <vector>
 #include <GL/glew.h>
 
@@ -47,8 +48,8 @@ public:
 	/// Convert coordinates into a tile index.
 	int IndexOf(int surface, int x, int y) const {
 		assert(0 <= surface && surface <= 5);
-		assert(0 <= x && x <= sidelength);
-		assert(0 <= y && y <= sidelength);
+		assert(0 <= x && x < sidelength);
+		assert(0 <= y && y < sidelength);
 		return surface * TilesPerSurface() + y * SideLength() + x;
 	}
 	/// The length of the side of each surface.
@@ -64,7 +65,15 @@ public:
 		return 6 * TilesPerSurface();
 	}
 
-	glm::dvec3 TileCenter(int surface, int x, int y) const noexcept;
+	double TileToPosition(int t) const noexcept { return double(t) - Radius(); }
+	int PositionToTile(double p) const noexcept { return int(p + Radius()); }
+
+	// tile coordinates of position on surface
+	glm::ivec2 SurfacePosition(int surface, const glm::dvec3 &) const noexcept;
+	// height of point over surface
+	double SurfaceElevation(int surface, const glm::dvec3 &) const noexcept;
+	// center point of tile on surface at elevation
+	glm::dvec3 TileCenter(int surface, int x, int y, double elevation = 0.0) const noexcept;
 
 	void BuildVAO(const Set<TileType> &);
 	void Draw(app::Assets &, graphics::Viewport &) override;
@@ -77,7 +86,7 @@ private:
 		glm::vec3 position;
 		glm::vec3 tex_coord;
 	};
-	graphics::SimpleVAO<Attributes, unsigned int> vao;
+	std::unique_ptr<graphics::SimpleVAO<Attributes, unsigned int>> vao;
 
 };
 
diff --git a/src/world/world.cpp b/src/world/world.cpp
index 0f9cb1e..0b1260f 100644
--- a/src/world/world.cpp
+++ b/src/world/world.cpp
@@ -290,28 +290,41 @@ Planet::Planet(int sidelength)
 Planet::~Planet() {
 }
 
-const TileType &Planet::TypeAt(int surface, int x, int y) const {
-	return GetSimulation().TileTypes()[TileAt(surface, x, y).type];
+const TileType &Planet::TypeAt(int srf, int x, int y) const {
+	return GetSimulation().TileTypes()[TileAt(srf, x, y).type];
 }
 
-glm::dvec3 Planet::TileCenter(int surface, int x, int y) const noexcept {
+glm::ivec2 Planet::SurfacePosition(int srf, const glm::dvec3 &pos) const noexcept {
+	return glm::ivec2(
+		PositionToTile(pos[(srf + 0) % 3]),
+		PositionToTile(pos[(srf + 1) % 3]));
+}
+
+double Planet::SurfaceElevation(int srf, const glm::dvec3 &pos) const noexcept {
+	return srf < 3
+		? pos[(srf + 2) % 3] - Radius()
+		: -pos[(srf + 2) % 3] - Radius();
+}
+
+glm::dvec3 Planet::TileCenter(int srf, int x, int y, double e) const noexcept {
 	glm::dvec3 center(0.0f);
-	center[(surface + 0) % 3] = x + 0.5 - Radius();
-	center[(surface + 1) % 3] = y + 0.5 - Radius();
-	center[(surface + 2) % 3] = surface < 3 ? Radius() : -Radius();
+	center[(srf + 0) % 3] = x + 0.5 - Radius();
+	center[(srf + 1) % 3] = y + 0.5 - Radius();
+	center[(srf + 2) % 3] = srf < 3 ? (Radius() + e) : -(Radius() + e);
 	return center;
 }
 
 void Planet::BuildVAO(const Set<TileType> &ts) {
-	vao.Bind();
-	vao.BindAttributes();
-	vao.EnableAttribute(0);
-	vao.EnableAttribute(1);
-	vao.AttributePointer<glm::vec3>(0, false, offsetof(Attributes, position));
-	vao.AttributePointer<glm::vec3>(1, false, offsetof(Attributes, tex_coord));
-	vao.ReserveAttributes(TilesTotal() * 4, GL_STATIC_DRAW);
+	vao.reset(new graphics::SimpleVAO<Attributes, unsigned int>);
+	vao->Bind();
+	vao->BindAttributes();
+	vao->EnableAttribute(0);
+	vao->EnableAttribute(1);
+	vao->AttributePointer<glm::vec3>(0, false, offsetof(Attributes, position));
+	vao->AttributePointer<glm::vec3>(1, false, offsetof(Attributes, tex_coord));
+	vao->ReserveAttributes(TilesTotal() * 4, GL_STATIC_DRAW);
 	{
-		auto attrib = vao.MapAttributes(GL_WRITE_ONLY);
+		auto attrib = vao->MapAttributes(GL_WRITE_ONLY);
 		float offset = Radius();
 
 		// srf  0  1  2  3  4  5
@@ -354,10 +367,10 @@ void Planet::BuildVAO(const Set<TileType> &ts) {
 			}
 		}
 	}
-	vao.BindElements();
-	vao.ReserveElements(TilesTotal() * 6, GL_STATIC_DRAW);
+	vao->BindElements();
+	vao->ReserveElements(TilesTotal() * 6, GL_STATIC_DRAW);
 	{
-		auto element = vao.MapElements(GL_WRITE_ONLY);
+		auto element = vao->MapElements(GL_WRITE_ONLY);
 		int index = 0;
 		for (int surface = 0; surface < 3; ++surface) {
 			for (int y = 0; y < sidelength; ++y) {
@@ -384,24 +397,26 @@ void Planet::BuildVAO(const Set<TileType> &ts) {
 			}
 		}
 	}
-	vao.Unbind();
+	vao->Unbind();
 }
 
 void Planet::Draw(app::Assets &assets, graphics::Viewport &viewport) {
-	vao.Bind();
+	if (!vao) return;
+
+	vao->Bind();
 	const glm::mat4 &MV = assets.shaders.planet_surface.MV();
 	assets.shaders.planet_surface.SetNormal(glm::vec3(MV * glm::vec4(0.0f, 0.0f, 1.0f, 0.0f)));
-	vao.DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 0);
+	vao->DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 0);
 	assets.shaders.planet_surface.SetNormal(glm::vec3(MV * glm::vec4(1.0f, 0.0f, 0.0f, 0.0f)));
-	vao.DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 1);
+	vao->DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 1);
 	assets.shaders.planet_surface.SetNormal(glm::vec3(MV * glm::vec4(0.0f, 1.0f, 0.0f, 0.0f)));
-	vao.DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 2);
+	vao->DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 2);
 	assets.shaders.planet_surface.SetNormal(glm::vec3(MV * glm::vec4(0.0f, 0.0f, -1.0f, 0.0f)));
-	vao.DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 3);
+	vao->DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 3);
 	assets.shaders.planet_surface.SetNormal(glm::vec3(MV * glm::vec4(-1.0f, 0.0f, 0.0f, 0.0f)));
-	vao.DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 4);
+	vao->DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 4);
 	assets.shaders.planet_surface.SetNormal(glm::vec3(MV * glm::vec4(0.0f, -1.0f, 0.0f, 0.0f)));
-	vao.DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 5);
+	vao->DrawTriangles(TilesPerSurface() * 6, TilesPerSurface() * 6 * 5);
 }
 
 
diff --git a/tst/assert.hpp b/tst/assert.hpp
index 85e4324..5042180 100644
--- a/tst/assert.hpp
+++ b/tst/assert.hpp
@@ -10,6 +10,23 @@
 namespace blobs {
 namespace test {
 
+template<class T>
+void AssertEqual(
+	const std::string &msg,
+	const glm::tvec2<T> &expected,
+	const glm::tvec2<T> &actual,
+	T epsilon = std::numeric_limits<T>::epsilon()
+) {
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		msg + " (X component)",
+		expected.x, actual.x, epsilon
+	);
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		msg + " (Y component)",
+		expected.y, actual.y, epsilon
+	);
+}
+
 template<class T>
 void AssertEqual(
 	const std::string &msg,
diff --git a/tst/world/PlanetTest.cpp b/tst/world/PlanetTest.cpp
new file mode 100644
index 0000000..1ab0bf4
--- /dev/null
+++ b/tst/world/PlanetTest.cpp
@@ -0,0 +1,79 @@
+#include "PlanetTest.hpp"
+
+#include "../assert.hpp"
+
+#include "world/Planet.hpp"
+
+#include <limits>
+
+CPPUNIT_TEST_SUITE_REGISTRATION(blobs::world::test::PlanetTest);
+
+using blobs::test::AssertEqual;
+
+
+namespace blobs {
+namespace world {
+namespace test {
+
+void PlanetTest::setUp() {
+}
+
+void PlanetTest::tearDown() {
+}
+
+
+void PlanetTest::testPositionConversion() {
+	Planet p(5);
+
+	CPPUNIT_ASSERT_EQUAL_MESSAGE(
+		"wrong sidelength of planet",
+		5, p.SideLength());
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		"wrong radius of planet",
+		2.5, p.Radius(), std::numeric_limits<double>::epsilon());
+
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		"wrong scalar conversion",
+		-2.5, p.TileToPosition(0), std::numeric_limits<double>::epsilon());
+	CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+		"wrong scalar conversion",
+		-0.5, p.TileToPosition(2), std::numeric_limits<double>::epsilon());
+	CPPUNIT_ASSERT_EQUAL_MESSAGE(
+		"wrong scalar conversion",
+		2, p.PositionToTile(0.1));
+	CPPUNIT_ASSERT_EQUAL_MESSAGE(
+		"wrong scalar conversion",
+		2, p.PositionToTile(-0.1));
+	CPPUNIT_ASSERT_EQUAL_MESSAGE(
+		"wrong scalar conversion",
+		1, p.PositionToTile(-0.6));
+	CPPUNIT_ASSERT_EQUAL_MESSAGE(
+		"wrong scalar conversion",
+		4, p.PositionToTile(2.0));
+
+	AssertEqual(
+		"wrong surface position",
+		glm::ivec2(2, 2), p.SurfacePosition(0, glm::dvec3(0.0, 0.0, 2.5))
+	);
+	AssertEqual(
+		"wrong surface position",
+		glm::ivec2(2, 2), p.SurfacePosition(0, glm::dvec3(0.1, 0.1, 2.5))
+	);
+	AssertEqual(
+		"wrong surface position",
+		glm::ivec2(2, 2), p.SurfacePosition(0, glm::dvec3(-0.1, -0.1, 2.5))
+	);
+	AssertEqual(
+		"wrong surface position",
+		glm::ivec2(3, 1), p.SurfacePosition(0, glm::dvec3(1.0, -1.0, 2.5))
+	);
+
+	AssertEqual(
+		"wrong tile center",
+		glm::dvec3(0.0, 0.0, 2.5), p.TileCenter(0, 2, 2)
+	);
+}
+
+}
+}
+}
diff --git a/tst/world/PlanetTest.hpp b/tst/world/PlanetTest.hpp
new file mode 100644
index 0000000..1fc4b15
--- /dev/null
+++ b/tst/world/PlanetTest.hpp
@@ -0,0 +1,32 @@
+#ifndef BLOBS_TEST_WORLD_PLANETTEST_HPP_
+#define BLOBS_TEST_WORLD_PLANETTEST_HPP_
+
+#include <cppunit/extensions/HelperMacros.h>
+
+
+namespace blobs {
+namespace world {
+namespace test {
+
+class PlanetTest
+: public CppUnit::TestFixture {
+
+CPPUNIT_TEST_SUITE(PlanetTest);
+
+CPPUNIT_TEST(testPositionConversion);
+
+CPPUNIT_TEST_SUITE_END();
+
+public:
+	void setUp();
+	void tearDown();
+
+	void testPositionConversion();
+
+};
+
+}
+}
+}
+
+#endif