X-Git-Url: http://git.localhorst.tv/?a=blobdiff_plain;f=src%2Fworld%2Fworld.cpp;h=bf68a9eca412f295c977e486c465e0794025366a;hb=f071bb512a09cece895e65ca48eba2a7155d6593;hp=3a1aac251f0bbb71cb9cd1414b9e55533ce9bd86;hpb=ee920127d653b8a3cfbee1efefde909ffa177662;p=blank.git

diff --git a/src/world/world.cpp b/src/world/world.cpp
index 3a1aac2..bf68a9e 100644
--- a/src/world/world.cpp
+++ b/src/world/world.cpp
@@ -1,4 +1,5 @@
 #include "Entity.hpp"
+#include "EntityCollision.hpp"
 #include "EntityController.hpp"
 #include "EntityDerivative.hpp"
 #include "EntityState.hpp"
@@ -11,6 +12,7 @@
 #include "../app/Assets.hpp"
 #include "../geometry/const.hpp"
 #include "../geometry/distance.hpp"
+#include "../geometry/rotation.hpp"
 #include "../graphics/Format.hpp"
 #include "../graphics/Viewport.hpp"
 
@@ -20,6 +22,7 @@
 #include <limits>
 #include <glm/gtx/euler_angles.hpp>
 #include <glm/gtx/io.hpp>
+#include <glm/gtx/projection.hpp>
 #include <glm/gtx/quaternion.hpp>
 #include <glm/gtx/rotate_vector.hpp>
 #include <glm/gtx/transform.hpp>
@@ -27,8 +30,16 @@
 
 namespace blank {
 
+namespace {
+
+/// used as a buffer for merging collisions
+std::vector<WorldCollision> col;
+
+}
+
 Entity::Entity() noexcept
-: ctrl(nullptr)
+: steering(*this)
+, ctrl(nullptr)
 , model()
 , id(-1)
 , name("anonymous")
@@ -50,7 +61,8 @@ Entity::~Entity() noexcept {
 }
 
 Entity::Entity(const Entity &other) noexcept
-: ctrl(other.ctrl)
+: steering(*this)
+, ctrl(other.ctrl)
 , model(other.model)
 , id(-1)
 , name(other.name)
@@ -89,11 +101,7 @@ void Entity::UnsetController() noexcept {
 }
 
 glm::vec3 Entity::ControlForce(const EntityState &s) const noexcept {
-	if (HasController()) {
-		return GetController().ControlForce(*this, s);
-	} else {
-		return -s.velocity;
-	}
+	return steering.Force(s);
 }
 
 void Entity::Position(const glm::ivec3 &c, const glm::vec3 &b) noexcept {
@@ -128,15 +136,58 @@ Ray Entity::Aim(const ExactLocation::Coarse &chunk_offset) const noexcept {
 	return Ray{ glm::vec3(transform[3]), -glm::vec3(transform[2]) };
 }
 
-void Entity::Update(float dt) {
-	UpdateTransforms();
-	UpdateHeading();
+void Entity::Update(World &world, float dt) {
 	if (HasController()) {
 		GetController().Update(*this, dt);
 	}
+	steering.Update(world, dt);
+	UpdatePhysics(world, dt);
+	UpdateTransforms();
+	UpdateHeading();
 	UpdateModel(dt);
 }
 
+void Entity::UpdatePhysics(World &world, float dt) {
+	EntityState s(state);
+
+	EntityDerivative a(CalculateStep(world, s, 0.0f, EntityDerivative()));
+	EntityDerivative b(CalculateStep(world, s, dt * 0.5f, a));
+	EntityDerivative c(CalculateStep(world, s, dt * 0.5f, b));
+	EntityDerivative d(CalculateStep(world, s, dt, c));
+
+	EntityDerivative f;
+	constexpr float sixth = 1.0f / 6.0f;
+	f.position = sixth * (a.position + 2.0f * (b.position + c.position) + d.position);
+	f.velocity = sixth * (a.velocity + 2.0f * (b.velocity + c.velocity) + d.velocity);
+
+	s.pos.block += f.position * dt;
+	s.velocity += f.velocity * dt;
+	limit(s.velocity, max_vel);
+	world.ResolveWorldCollision(*this, s);
+	s.AdjustPosition();
+
+	SetState(s);
+}
+
+EntityDerivative Entity::CalculateStep(
+	World &world,
+	const EntityState &cur,
+	float dt,
+	const EntityDerivative &delta
+) const {
+	EntityState next(cur);
+	next.pos.block += delta.position * dt;
+	next.velocity += delta.velocity * dt;
+	limit(next.velocity, max_vel);
+	next.AdjustPosition();
+
+	EntityDerivative out;
+	out.position = next.velocity;
+	out.velocity = ControlForce(next) + world.GravityAt(next.pos); // by mass = 1kg
+	return out;
+}
+
+
 void Entity::UpdateTransforms() noexcept {
 	// model transform is the one given by current state
 	model_transform = state.Transform(state.pos.chunk);
@@ -209,7 +260,7 @@ void Entity::OrientBody(float dt) noexcept {
 				std::cout << "direction: " << direction << std::endl;
 				std::cout << "difference: " << glm::degrees(relative_difference) << "°" << std::endl;
 				std::cout << "correction: " << glm::degrees(correction) << "°" << std::endl;
-				std::cout  << std::endl;
+				std::cout << std::endl;
 			}
 			// now rotate body by correction and head by -correction
 			state.orient = rotate(state.orient, correction, up);
@@ -219,8 +270,8 @@ void Entity::OrientBody(float dt) noexcept {
 }
 
 void Entity::OrientHead(float dt) noexcept {
-	// maximum yaw of head (90°)
-	constexpr float max_head_yaw = PI_0p5;
+	// maximum yaw of head (60°)
+	constexpr float max_head_yaw = PI / 3.0f;
 	// use local Y as up
 	const glm::vec3 up(model_transform[1]);
 	// if yaw is bigger than max, rotate the body to accomodate
@@ -240,31 +291,46 @@ void Entity::OrientHead(float dt) noexcept {
 }
 
 
-EntityController::~EntityController() {
+EntityCollision::EntityCollision(Entity *e, float d, const glm::vec3 &n)
+: depth(d)
+, normal(n)
+, entity(e) {
+	if (entity) {
+		entity->Ref();
+	}
+}
 
+EntityCollision::~EntityCollision() {
+	if (entity) {
+		entity->UnRef();
+	}
 }
 
-bool EntityController::MaxOutForce(
-	glm::vec3 &out,
-	const glm::vec3 &add,
-	float max
-) noexcept {
-	if (iszero(add) || any(isnan(add))) {
-		return false;
+EntityCollision::EntityCollision(const EntityCollision &other)
+: depth(other.depth)
+, normal(other.normal)
+, entity(other.entity) {
+	if (entity) {
+		entity->Ref();
 	}
-	float current = iszero(out) ? 0.0f : length(out);
-	float remain = max - current;
-	if (remain <= 0.0f) {
-		return true;
+}
+
+EntityCollision &EntityCollision::operator =(const EntityCollision &other) {
+	if (entity) {
+		entity->UnRef();
 	}
-	float additional = length(add);
-	if (additional > remain) {
-		out += normalize(add) * remain;
-		return true;
-	} else {
-		out += add;
-		return false;
+	depth = other.depth;
+	normal = other.normal;
+	entity = other.entity;
+	if (entity) {
+		entity->Ref();
 	}
+	return *this;
+}
+
+
+EntityController::~EntityController() {
+
 }
 
 
@@ -328,19 +394,270 @@ void Player::Update(int dt) {
 }
 
 
+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;
+}
+
+
 World::World(const BlockTypeRegistry &types, const Config &config)
 : config(config)
 , block_type(types)
 , chunks(types)
 , players()
 , entities()
+, rng(
+#ifdef BLANK_PROFILING
+0
+#else
+std::time(nullptr)
+#endif
+)
 , light_direction(config.light_direction)
 , fog_density(config.fog_density) {
-
+	for (int i = 0; i < 4; ++i) {
+		rng.Next<int>();
+	}
 }
 
 World::~World() {
-
+	for (Entity &e : entities) {
+		e.Kill();
+	}
+	std::size_t removed = 0;
+	do {
+		removed = 0;
+		for (auto e = entities.begin(), end = entities.end(); e != end; ++e) {
+			if (e->CanRemove()) {
+				e = RemoveEntity(e);
+				end = entities.end();
+				++removed;
+			}
+		}
+	} while (removed > 0 && !entities.empty());
 }
 
 
@@ -459,16 +776,25 @@ std::vector<Candidate> candidates;
 
 bool World::Intersection(
 	const Ray &ray,
-	const glm::mat4 &M,
 	const ExactLocation::Coarse &reference,
 	WorldCollision &coll
 ) {
+	// only consider chunks of the idex closest to reference
+	// this makes the ray not be infinite anymore (which means it's
+	// actually a line segment), but oh well
+	ChunkIndex *index = chunks.ClosestIndex(reference);
+	if (!index) {
+		return false;
+	}
+
 	candidates.clear();
 
-	for (Chunk &cur_chunk : chunks) {
+	// TODO: convert to coords based iteration and trim based
+	//       on ray direction
+	for (Chunk *cur_chunk : *index) {
 		float cur_dist;
-		if (cur_chunk.Intersection(ray, M * cur_chunk.Transform(reference), cur_dist)) {
-			candidates.push_back({ &cur_chunk, cur_dist });
+		if (cur_chunk && cur_chunk->Intersection(ray, reference, cur_dist)) {
+			candidates.push_back({ cur_chunk, cur_dist });
 		}
 	}
 
@@ -483,7 +809,7 @@ bool World::Intersection(
 	for (Candidate &cand : candidates) {
 		if (cand.dist > coll.depth) continue;
 		WorldCollision cur_coll;
-		if (cand.chunk->Intersection(ray, M * cand.chunk->Transform(reference), cur_coll)) {
+		if (cand.chunk->Intersection(ray, reference, cur_coll)) {
 			if (cur_coll.depth < coll.depth) {
 				coll = cur_coll;
 			}
@@ -495,47 +821,43 @@ bool World::Intersection(
 
 bool World::Intersection(
 	const Ray &ray,
-	const glm::mat4 &M,
 	const Entity &reference,
 	EntityCollision &coll
 ) {
-	coll.entity = nullptr;
-	coll.depth = std::numeric_limits<float>::infinity();
+	coll = EntityCollision(nullptr, std::numeric_limits<float>::infinity(), glm::vec3(0.0f));
 	for (Entity &cur_entity : entities) {
 		if (&cur_entity == &reference) {
 			continue;
 		}
 		float cur_dist;
 		glm::vec3 cur_normal;
-		if (blank::Intersection(ray, cur_entity.Bounds(), M * cur_entity.Transform(reference.ChunkCoords()), &cur_dist, &cur_normal)) {
+		if (blank::Intersection(ray, cur_entity.Bounds(), cur_entity.Transform(reference.ChunkCoords()), &cur_dist, &cur_normal)) {
 			// TODO: fine grained check goes here? maybe?
 			if (cur_dist < coll.depth) {
-				coll.entity = &cur_entity;
-				coll.depth = cur_dist;
-				coll.normal = cur_normal;
+				coll = EntityCollision(&cur_entity, cur_dist, cur_normal);
 			}
 		}
 	}
 
-	return coll.entity;
+	return coll;
 }
 
 bool World::Intersection(const Entity &e, const EntityState &s, std::vector<WorldCollision> &col) {
-	// TODO: make special case for entities here and in Chunk::Intersection so entity's bounding radius
-	//       doesn't have to be calculated over and over again (sqrt)
-	AABB box = e.Bounds();
 	glm::ivec3 reference = s.pos.chunk;
 	glm::mat4 M = s.Transform(reference);
 
+	ExactLocation::Coarse begin(reference - 1);
+	ExactLocation::Coarse end(reference + 2);
+
 	bool any = false;
-	for (Chunk &cur_chunk : chunks) {
-		if (manhattan_radius(cur_chunk.Position() - reference) > 1) {
-			// chunk is not one of the 3x3x3 surrounding the entity
-			// since there's no entity which can extent over 16 blocks, they can be skipped
-			continue;
-		}
-		if (cur_chunk.Intersection(box, M, cur_chunk.Transform(reference), col)) {
-			any = true;
+	for (ExactLocation::Coarse pos(begin); pos.z < end.z; ++pos.z) {
+		for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
+			for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
+				Chunk *chunk = chunks.Get(pos);
+				if (chunk && chunk->Intersection(e, M, chunk->Transform(reference), col)) {
+					any = true;
+				}
+			}
 		}
 	}
 	return any;
@@ -547,15 +869,19 @@ bool World::Intersection(
 	const glm::ivec3 &reference,
 	std::vector<WorldCollision> &col
 ) {
+	// this only works if box's diameter is < than 16
+	ExactLocation::Coarse begin(reference - 1);
+	ExactLocation::Coarse end(reference + 2);
+
 	bool any = false;
-	for (Chunk &cur_chunk : chunks) {
-		if (manhattan_radius(cur_chunk.Position() - reference) > 1) {
-			// chunk is not one of the 3x3x3 surrounding the entity
-			// since there's no entity which can extent over 16 blocks, they can be skipped
-			continue;
-		}
-		if (cur_chunk.Intersection(box, M, cur_chunk.Transform(reference), col)) {
-			any = true;
+	for (ExactLocation::Coarse pos(begin); pos.z < end.z; ++pos.z) {
+		for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
+			for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
+				Chunk *chunk = chunks.Get(pos);
+				if (chunk && chunk->Intersection(box, M, chunk->Transform(reference), col)) {
+					any = true;
+				}
+			}
 		}
 	}
 	return any;
@@ -564,10 +890,7 @@ bool World::Intersection(
 void World::Update(int dt) {
 	float fdt(dt * 0.001f);
 	for (Entity &entity : entities) {
-		Update(entity, fdt);
-	}
-	for (Entity &entity : entities) {
-		entity.Update(fdt);
+		entity.Update(*this, fdt);
 	}
 	for (Player &player : players) {
 		player.Update(dt);
@@ -581,125 +904,88 @@ void World::Update(int dt) {
 	}
 }
 
-void World::Update(Entity &entity, float dt) {
-	EntityState state(entity.GetState());
-
-	EntityDerivative a(CalculateStep(entity, state, 0.0f, EntityDerivative()));
-	EntityDerivative b(CalculateStep(entity, state, dt * 0.5f, a));
-	EntityDerivative c(CalculateStep(entity, state, dt * 0.5f, b));
-	EntityDerivative d(CalculateStep(entity, state, dt, c));
-
-	EntityDerivative f;
-	constexpr float sixth = 1.0f / 6.0f;
-	f.position = sixth * ((a.position + 2.0f * (b.position + c.position)) + d.position);
-	f.velocity = sixth * ((a.velocity + 2.0f * (b.velocity + c.velocity)) + d.velocity);
-
-	state.pos.block += f.position * dt;
-	state.velocity += f.velocity * dt;
-	state.AdjustPosition();
-
-	entity.SetState(state);
-}
-
-EntityDerivative World::CalculateStep(
+void World::ResolveWorldCollision(
 	const Entity &entity,
-	const EntityState &cur,
-	float dt,
-	const EntityDerivative &delta
+	EntityState &state
 ) {
-	EntityState next(cur);
-	next.pos.block += delta.position * dt;
-	next.velocity += delta.velocity * dt;
-	next.AdjustPosition();
-
-	if (dot(next.velocity, next.velocity) > entity.MaxVelocity() * entity.MaxVelocity()) {
-		next.velocity = normalize(next.velocity) * entity.MaxVelocity();
+	col.clear();
+	if (!entity.WorldCollidable() || !Intersection(entity, state, col)) {
+		// no collision, no fix
+		return;
 	}
-
-	EntityDerivative out;
-	out.position = next.velocity;
-	out.velocity = CalculateForce(entity, next); // by mass = 1kg
-	return out;
-}
-
-glm::vec3 World::CalculateForce(
-	const Entity &entity,
-	const EntityState &state
-) {
-	glm::vec3 force(ControlForce(entity, state) + CollisionForce(entity, state) + Gravity(entity, state));
-	if (dot(force, force) > entity.MaxControlForce() * entity.MaxControlForce()) {
-		return normalize(force) * entity.MaxControlForce();
-	} else {
-		return force;
+	glm::vec3 correction = CombinedInterpenetration(state, col);
+	// correction may be zero in which case normalize() returns NaNs
+	if (iszero(correction)) {
+		return;
 	}
+	// if entity is already going in the direction of correction,
+	// let the problem resolve itself
+	if (dot(state.velocity, correction) >= 0.0f) {
+		return;
+	}
+	// apply correction, maybe could use some damping, gotta test
+	state.pos.block += correction;
+	// kill velocity?
+	glm::vec3 normal_velocity(proj(state.velocity, correction));
+	state.velocity -= normal_velocity;
 }
 
-glm::vec3 World::ControlForce(
-	const Entity &entity,
-	const EntityState &state
-) {
-	return entity.ControlForce(state);
-}
-
-namespace {
-
-std::vector<WorldCollision> col;
-
-}
-
-glm::vec3 World::CollisionForce(
-	const Entity &entity,
-	const EntityState &state
-) {
-	col.clear();
-	if (entity.WorldCollidable() && Intersection(entity, state, col)) {
-		// determine displacement for each cardinal axis and move entity accordingly
-		glm::vec3 min_pen(0.0f);
-		glm::vec3 max_pen(0.0f);
-		for (const WorldCollision &c : col) {
-			if (!c.Blocks()) continue;
-			glm::vec3 local_pen(c.normal * c.depth);
-			// swap if neccessary (normal may point away from the entity)
-			if (dot(c.normal, state.RelativePosition(c.ChunkPos()) - c.BlockCoords()) > 0) {
-				local_pen *= -1;
+glm::vec3 World::CombinedInterpenetration(
+	const EntityState &state,
+	const std::vector<WorldCollision> &col
+) noexcept {
+	// determine displacement for each cardinal axis and move entity accordingly
+	glm::vec3 min_pen(0.0f);
+	glm::vec3 max_pen(0.0f);
+	for (const WorldCollision &c : col) {
+		if (!c.Blocks()) continue;
+		glm::vec3 normal(c.normal);
+		// swap if neccessary (normal may point away from the entity)
+		if (dot(normal, state.RelativePosition(c.ChunkPos()) - c.BlockCoords()) < 0) {
+			normal = -normal;
+		}
+		// check if block surface is "inside"
+		Block::Face coll_face = Block::NormalFace(normal);
+		BlockLookup neighbor(c.chunk, c.BlockPos(), coll_face);
+		if (neighbor && neighbor.FaceFilled(Block::Opposite(coll_face))) {
+			// yep, so ignore this contact
+			continue;
+		}
+		glm::vec3 local_pen(normal * c.depth);
+		min_pen = min(min_pen, local_pen);
+		max_pen = max(max_pen, local_pen);
+	}
+	glm::vec3 pen(0.0f);
+	// only apply correction for axes where penetration is only in one direction
+	for (std::size_t i = 0; i < 3; ++i) {
+		if (min_pen[i] < -std::numeric_limits<float>::epsilon()) {
+			if (max_pen[i] < std::numeric_limits<float>::epsilon()) {
+				pen[i] = min_pen[i];
 			}
-			min_pen = min(min_pen, local_pen);
-			max_pen = max(max_pen, local_pen);
+		} else {
+			pen[i] = max_pen[i];
 		}
-		glm::vec3 correction(0.0f);
-		// only apply correction for axes where penetration is only in one direction
-		for (std::size_t i = 0; i < 3; ++i) {
-			if (min_pen[i] < -std::numeric_limits<float>::epsilon()) {
-				if (max_pen[i] < std::numeric_limits<float>::epsilon()) {
-					correction[i] = -min_pen[i];
+	}
+	return pen;
+}
+
+glm::vec3 World::GravityAt(const ExactLocation &loc) const noexcept {
+	glm::vec3 force(0.0f);
+	ExactLocation::Coarse begin(loc.chunk - 1);
+	ExactLocation::Coarse end(loc.chunk + 2);
+
+	for (ExactLocation::Coarse pos(begin); pos.z < end.z; ++pos.z) {
+		for (pos.y = begin.y; pos.y < end.y; ++pos.y) {
+			for (pos.x = begin.x; pos.x < end.x; ++pos.x) {
+				const Chunk *chunk = chunks.Get(pos);
+				if (chunk) {
+					force += chunk->GravityAt(loc);
 				}
-			} else {
-				correction[i] = -max_pen[i];
 			}
 		}
-		// correction may be zero in which case normalize() returns NaNs
-		if (dot(correction, correction) < std::numeric_limits<float>::epsilon()) {
-			return glm::vec3(0.0f);
-		}
-		glm::vec3 normal(normalize(correction));
-		glm::vec3 normal_velocity(normal * dot(state.velocity, normal));
-		// apply force proportional to penetration
-		// use velocity projected onto normal as damper
-		constexpr float k = 1000.0f; // spring constant
-		constexpr float b = 10.0f; // damper constant
-		const glm::vec3 x(-correction); // endpoint displacement from equilibrium in m
-		const glm::vec3 v(normal_velocity); // relative velocity between endpoints in m/s
-		return (((-k) * x) - (b * v)); // times 1kg/s, in kg*m/s²
-	} else {
-		return glm::vec3(0.0f);
 	}
-}
 
-glm::vec3 World::Gravity(
-	const Entity &entity,
-	const EntityState &state
-) {
-	return glm::vec3(0.0f);
+	return force;
 }
 
 World::EntityHandle World::RemoveEntity(EntityHandle &eh) {
@@ -743,23 +1029,23 @@ void World::GetLight(
 	glm::vec3 &col,
 	glm::vec3 &amb
 ) {
-	Chunk *chunk = chunks.Get(e.ChunkCoords());
-	if (!chunk) {
+	BlockLookup center(chunks.Get(e.ChunkCoords()), e.Position());
+	if (!center) {
 		// chunk unavailable, so make it really dark and from
 		// some arbitrary direction
 		dir = glm::vec3(1.0f, 2.0f, 3.0f);
 		col = glm::vec3(0.025f); // ~0.8^15
 		return;
 	}
-	glm::ivec3 base(e.Position());
-	int base_light = chunk->GetLight(base);
+	glm::ivec3 base(center.GetBlockPos());
+	int base_light = center.GetLight();
 	int max_light = 0;
 	int min_light = 15;
 	glm::ivec3 acc(0, 0, 0);
 	for (glm::ivec3 offset(-1, -1, -1); offset.z < 2; ++offset.z) {
 		for (offset.y = -1; offset.y < 2; ++offset.y) {
 			for (offset.x = -1; offset.x < 2; ++offset.x) {
-				BlockLookup block(chunk, base + offset);
+				BlockLookup block(&center.GetChunk(), center.GetBlockPos() + offset);
 				if (!block) {
 					// missing, just ignore it
 					continue;
@@ -786,7 +1072,7 @@ void World::RenderDebug(Viewport &viewport) {
 	PrimitiveMesh debug_mesh;
 	PlainColor &prog = viewport.WorldColorProgram();
 	for (const Entity &entity : entities) {
-		debug_buf.OutlineBox(entity.Bounds(), glm::vec4(1.0f, 0.0f, 0.0f, 1.0f));
+		debug_buf.OutlineBox(entity.Bounds(), glm::tvec4<unsigned char>(255, 0, 0, 255));
 		debug_mesh.Update(debug_buf);
 		prog.SetM(entity.Transform(players.front().GetEntity().ChunkCoords()));
 		debug_mesh.DrawLines();