From 4da2ae6f12d7cf4594edb2d560c5c112e9bcd094 Mon Sep 17 00:00:00 2001
From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Mon, 19 Oct 2015 12:43:19 +0200
Subject: [PATCH] use seconds as world time unit

---
 src/ai/ai.cpp                 |  6 +++---
 src/client/NetworkedInput.hpp |  4 ++--
 src/client/net.cpp            |  4 ++--
 src/ui/ui.cpp                 |  2 +-
 src/world/Entity.hpp          |  2 +-
 src/world/World.hpp           |  2 ++
 src/world/world.cpp           | 26 ++++++++++++--------------
 7 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/src/ai/ai.cpp b/src/ai/ai.cpp
index 7ada5a3..7dfe042 100644
--- a/src/ai/ai.cpp
+++ b/src/ai/ai.cpp
@@ -16,8 +16,8 @@ Chaser::Chaser(World &world, Entity &ctrl, Entity &tgt) noexcept
 : Controller(ctrl)
 , world(world)
 , tgt(tgt)
-, chase_speed(0.002f)
-, flee_speed(-0.005f)
+, chase_speed(2.0f)
+, flee_speed(-5.0f)
 , stop_dist(10)
 , flee_dist(5) {
 	tgt.Ref();
@@ -109,7 +109,7 @@ void RandomWalk::Change() noexcept {
 	start_vel = target_vel;
 	start_rot = target_rot;
 
-	constexpr float base = 0.000001f;
+	constexpr float base = 0.001f;
 
 	target_vel.x = base * (random.Next<short>() % 1024);
 	target_vel.y = base * (random.Next<short>() % 1024);
diff --git a/src/client/NetworkedInput.hpp b/src/client/NetworkedInput.hpp
index 36382b9..a670222 100644
--- a/src/client/NetworkedInput.hpp
+++ b/src/client/NetworkedInput.hpp
@@ -37,9 +37,9 @@ private:
 	struct PlayerHistory {
 		EntityState state;
 		glm::vec3 tgt_vel;
-		int delta_t;
+		float delta_t;
 		std::uint16_t packet;
-		PlayerHistory(EntityState s, const glm::vec3 &tv, int dt, std::uint16_t p)
+		PlayerHistory(EntityState s, const glm::vec3 &tv, float dt, std::uint16_t p)
 		: state(s), tgt_vel(tv), delta_t(dt), packet(p) { }
 	};
 	std::list<PlayerHistory> player_hist;
diff --git a/src/client/net.cpp b/src/client/net.cpp
index 8a49304..c3bbb67 100644
--- a/src/client/net.cpp
+++ b/src/client/net.cpp
@@ -332,12 +332,12 @@ void NetworkedInput::PushPlayerUpdate(int dt) {
 		InventorySlot()
 	);
 	if (player_hist.size() < 16) {
-		player_hist.emplace_back(state, GetPlayer().GetEntity().TargetVelocity(), dt, packet);
+		player_hist.emplace_back(state, GetPlayer().GetEntity().TargetVelocity(), dt * 0.001f, packet);
 	} else {
 		auto entry = player_hist.begin();
 		entry->state = state;
 		entry->tgt_vel = GetPlayer().GetEntity().TargetVelocity();
-		entry->delta_t = dt;
+		entry->delta_t = dt * 0.001f;
 		entry->packet = packet;
 		player_hist.splice(player_hist.end(), player_hist, entry);
 	}
diff --git a/src/ui/ui.cpp b/src/ui/ui.cpp
index 9638619..5b0eec8 100644
--- a/src/ui/ui.cpp
+++ b/src/ui/ui.cpp
@@ -83,7 +83,7 @@ void PlayerController::Invalidate() noexcept {
 }
 
 void PlayerController::UpdatePlayer() noexcept {
-	constexpr float max_vel = 0.005f;
+	constexpr float max_vel = 5.0f; // in m/s
 	if (dirty) {
 		player.GetEntity().Orientation(glm::quat(glm::vec3(pitch, yaw, 0.0f)));
 		player.GetEntity().TargetVelocity(glm::rotateY(move_dir * max_vel, yaw));
diff --git a/src/world/Entity.hpp b/src/world/Entity.hpp
index 1ac9223..7e85591 100644
--- a/src/world/Entity.hpp
+++ b/src/world/Entity.hpp
@@ -56,7 +56,7 @@ public:
 		return state.Diff(other.state);
 	}
 
-	/// direction is rotation axis, magnitude is speed in rad/ms
+	/// direction is rotation axis, magnitude is speed in rad/s
 	const glm::vec3 &AngularVelocity() const noexcept { return state.ang_vel; }
 	void AngularVelocity(const glm::vec3 &v) noexcept { state.ang_vel = v; }
 
diff --git a/src/world/World.hpp b/src/world/World.hpp
index c24ccf3..4755b18 100644
--- a/src/world/World.hpp
+++ b/src/world/World.hpp
@@ -89,7 +89,9 @@ public:
 	std::list<Entity> &Entities() noexcept { return entities; }
 	const std::list<Entity> &Entities() const noexcept { return entities; }
 
+	// dt in ms
 	void Update(int dt);
+	// dt in s
 	void Update(Entity &, float dt);
 
 	void Render(Viewport &);
diff --git a/src/world/world.cpp b/src/world/world.cpp
index 750cd2d..15f1cab 100644
--- a/src/world/world.cpp
+++ b/src/world/world.cpp
@@ -342,7 +342,7 @@ bool World::Intersection(const Entity &e, const EntityState &s, std::vector<Worl
 
 
 void World::Update(int dt) {
-	float fdt(dt);
+	float fdt(dt * 0.001f);
 	for (Entity &entity : entities) {
 		Update(entity, fdt);
 	}
@@ -409,7 +409,7 @@ EntityDerivative World::CalculateStep(
 
 	EntityDerivative out;
 	out.position = next.velocity;
-	out.velocity = CalculateForce(entity, next); // by mass = 1
+	out.velocity = CalculateForce(entity, next); // by mass = 1kg
 	return out;
 }
 
@@ -424,12 +424,11 @@ glm::vec3 World::ControlForce(
 	const Entity &entity,
 	const EntityState &state
 ) {
-	constexpr float k = 1.0f; // spring constant
-	constexpr float b = 1.0f; // damper constant
-	constexpr float t = 0.01f; // 1/time constant
-	const glm::vec3 x(-entity.TargetVelocity()); // endpoint displacement from equilibrium
-	const glm::vec3 v(state.velocity); // relative velocity between endpoints
-	return (((-k) * x) - (b * v)) * t; // times mass = 1
+	constexpr float k = 10.0f; // spring constant
+	constexpr float b = 10.0f; // damper constant
+	const glm::vec3 x(-entity.TargetVelocity()); // endpoint displacement from equilibrium, by 1s, in m
+	const glm::vec3 v(state.velocity); // relative velocity between endpoints in m/s
+	return ((-k) * x) - (b * v); // times 1kg/s, in kg*m/s²
 }
 
 namespace {
@@ -462,12 +461,11 @@ glm::vec3 World::CollisionForce(
 		glm::vec3 normal_velocity(normal * dot(state.velocity, normal));
 		// apply force proportional to penetration
 		// use velocity projected onto normal as damper
-		constexpr float k = 1.0f; // spring constant
-		constexpr float b = 1.0f; // damper constant
-		constexpr float t = 0.001f; // 1/time constant
-		const glm::vec3 x(penetration); // endpoint displacement from equilibrium
-		const glm::vec3 v(normal_velocity); // relative velocity between endpoints
-		return (((-k) * x) - (b * v)) * t; // times mass = 1
+		constexpr float k = 1000.0f; // spring constant
+		constexpr float b = 100.0f; // damper constant
+		const glm::vec3 x(penetration); // 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);
 	}
-- 
2.39.2