From 593a056696369f0fa7a83acffcf2cb29c5dcc3dc Mon Sep 17 00:00:00 2001
From: Diogo Cruz Diniz <diogocruzdiniz@gmail.com>
Date: Fri, 17 Apr 2026 17:24:56 +0100
Subject: [PATCH] feat: Aircraft trails

---
 src/sim/af_spawner.cpp     |  6 +++---
 src/sim/af_spawner.hpp     |  7 ++++++-
 src/sim/aircraft.cpp       |  7 +++++++
 src/sim/aircraft.hpp       |  9 ++++++++-
 src/sim/aircraft_trail.cpp | 18 ++++++++++++++++++
 src/sim/aircraft_trail.hpp | 22 ++++++++++++++++++++++
 src/sim/airfield.cpp       |  4 ++--
 src/sim/airfield.hpp       |  3 +++
 8 files changed, 69 insertions(+), 7 deletions(-)
 create mode 100644 src/sim/aircraft_trail.cpp
 create mode 100644 src/sim/aircraft_trail.hpp

diff --git a/src/sim/af_spawner.cpp b/src/sim/af_spawner.cpp
index 6ec9179..0ca6f1d 100644
--- a/src/sim/af_spawner.cpp
+++ b/src/sim/af_spawner.cpp
@@ -4,14 +4,14 @@ void dxd::sim::AFSpawner::tick(float timestep, World *world)
 {
 	(void)timestep;
 
-	if (_next_spawn-- != 0)
+	if (--_next_spawn != 0)
 		return;
 
-	_next_spawn = 60 + SDL_rand(120);
+	_next_spawn = _MIN_SPAWN_DELAY + SDL_rand(_MAX_SPAWN_DELAY);
 
 	//Pos should spawn in a grid, check if free, and offset random from grid coord to look natural
 	vec2 pos = {(SDL_randf()-.5f)*2*60.0f, (SDL_randf()-.5f)*2*60.0f};
-	Airfield *af = new Airfield(pos, 180 + SDL_rand(600));
+	Airfield *af = new Airfield(pos, _MIN_AF_TTL + SDL_rand(_MAX_AF_TTL));
 	world->add_obj(af);
 	_airfields.push_back(af);
 }
diff --git a/src/sim/af_spawner.hpp b/src/sim/af_spawner.hpp
index f49f6aa..22f00a3 100644
--- a/src/sim/af_spawner.hpp
+++ b/src/sim/af_spawner.hpp
@@ -15,11 +15,16 @@ private:
 	std::vector<Airfield*> _airfields;
 	int _next_spawn;
 
+	const int _MIN_SPAWN_DELAY = 450;
+	const int _MAX_SPAWN_DELAY = 3000;
+	const int _MIN_AF_TTL = 1200;
+	const int _MAX_AF_TTL = 6000;
+
 public:
 	AFSpawner()
 	{
 		_airfields = std::vector<Airfield*>();
-		_next_spawn = 0;
+		_next_spawn = 1;
 	}
 
 	void tick(float timestep, World *world) override;
diff --git a/src/sim/aircraft.cpp b/src/sim/aircraft.cpp
index 3b383db..5b91b48 100644
--- a/src/sim/aircraft.cpp
+++ b/src/sim/aircraft.cpp
@@ -1,10 +1,17 @@
 #include "aircraft.hpp"
+#include "aircraft_trail.hpp"
 
 void dxd::sim::Aircraft::tick(float timestep, World *world)
 {
 	(void)world;
 
 	_position = _position + polar_to_vec2(_direction, _speed) * timestep;
+
+	if (--_trail_cooldown == 0)
+	{
+		world->add_obj(new AircraftTrail(_position, _TRAIL_DURATION));
+		_trail_cooldown = _TRAIL_DELAY;
+	}
 }
 
 void dxd::sim::Aircraft::draw(Renderer *rend)
diff --git a/src/sim/aircraft.hpp b/src/sim/aircraft.hpp
index f0cbdd7..a4fbba1 100644
--- a/src/sim/aircraft.hpp
+++ b/src/sim/aircraft.hpp
@@ -12,10 +12,17 @@ private:
 	vec2 _position;
 	float _direction;
 	float _speed;
+	int _trail_cooldown;
+
+	const int _TRAIL_DELAY = 60;
+	const int _TRAIL_DURATION = 420;
 
 public:
 	Aircraft(vec2 position, float direction, float speed)
-		: _position(position), _direction(direction), _speed(speed) {}
+		: _position(position), _direction(direction), _speed(speed)
+	{
+		_trail_cooldown = _TRAIL_DELAY;
+	}
 
 	void tick(float timestep, World *world) override;
 	void draw(Renderer *rend) override;
diff --git a/src/sim/aircraft_trail.cpp b/src/sim/aircraft_trail.cpp
new file mode 100644
index 0000000..54a6a2b
--- /dev/null
+++ b/src/sim/aircraft_trail.cpp
@@ -0,0 +1,18 @@
+#include "aircraft_trail.hpp"
+
+void dxd::sim::AircraftTrail::tick(float timestep, World *world)
+{
+	(void)timestep;
+
+	if (--_ttl == 0)
+	{
+		world->remove_obj(this);
+		return;
+	}
+}
+
+void dxd::sim::AircraftTrail::draw(Renderer *rend)
+{
+	rend->color(128, 128, 128, 255);
+	rend->box(_position, .5);
+}
diff --git a/src/sim/aircraft_trail.hpp b/src/sim/aircraft_trail.hpp
new file mode 100644
index 0000000..2290a1c
--- /dev/null
+++ b/src/sim/aircraft_trail.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "../math.hpp"
+#include "world_object.hpp"
+
+namespace dxd::sim
+{
+
+class AircraftTrail : public WorldObject
+{
+private:
+	vec2 _position;
+	int _ttl;
+
+public:
+	AircraftTrail(vec2 position, int ttl) : _position(position), _ttl(ttl) {}
+
+	void tick(float timestep, World *world) override;
+	void draw(Renderer *rend) override;
+};
+
+} // namespace dxd::sim
diff --git a/src/sim/airfield.cpp b/src/sim/airfield.cpp
index 9292c5a..7bb1622 100644
--- a/src/sim/airfield.cpp
+++ b/src/sim/airfield.cpp
@@ -13,9 +13,9 @@ void dxd::sim::Airfield::tick(float timestep, World *world)
 
 	if (--_next_spawn == 0)
 	{
-		Aircraft *af = new Aircraft(_position, SDL_randf() * M_PIf, 5.0f);
+		Aircraft *af = new Aircraft(_position, SDL_randf() * 2 * M_PIf, 5.0f);
 		world->add_obj(af);
-		_next_spawn = 60 + SDL_rand(240);
+		_next_spawn = _MIN_TAKEOFF_DELAY + SDL_rand(_MAX_TAKEOFF_DELAY - _MIN_TAKEOFF_DELAY);
 	}
 }
 
diff --git a/src/sim/airfield.hpp b/src/sim/airfield.hpp
index de2309b..5a827f1 100644
--- a/src/sim/airfield.hpp
+++ b/src/sim/airfield.hpp
@@ -15,6 +15,9 @@ private:
 	int _ttl;
 	int _next_spawn;
 
+	const int _MIN_TAKEOFF_DELAY = 240;
+	const int _MAX_TAKEOFF_DELAY = 600;
+
 public:
 	Airfield(vec2 position, int ttl) : _position(position), _ttl(ttl)
 	{