fix: Corrected trigonometrry

src/math.hpp

@@ -102,8 +102,30 @@ static vec2 max2(vec2 const &a, vec2 const &b)
 
 static vec2 polar_to_vec2(const float angle, const float len)
 {
+    // 0 (north) up, PI/2 (east) right
     return {
         .x = len * sinf(angle),
         .y = len * cosf(angle)
     };
 }
+
+static float vec2_angle(const vec2 v)
+{
+    return atan2f(v.x, v.y);
+}
+
+static float normalize_angle(const float angle)
+{
+    float a = angle;
+    while (a > 2*M_PIf) a -= 2*M_PIf;
+	while (a < 0) a += 2*M_PIf;
+    return a;
+}
+
+static float normalize_angle_diff(const float diff)
+{
+    float d = diff;
+    while (d > M_PIf) d -= 2*M_PIf;
+	while (d < -M_PIf) d += 2*M_PIf;
+    return d;
+}

src/sim/af_spawner.cpp

@@ -1,5 +1,7 @@
 #include "af_spawner.hpp"
 
+#include <math.h>
+
 void dxd::sim::AFSpawner::tick(float timestep, World *world)
 {
 	(void)timestep;
@@ -11,7 +13,7 @@ void dxd::sim::AFSpawner::tick(float timestep, World *world)
 
 	//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, _MIN_AF_TTL + SDL_rand(_MAX_AF_TTL));
+	Airfield *af = new Airfield(pos, _MIN_AF_TTL + SDL_rand(_MAX_AF_TTL), SDL_randf()*2*M_PIf);
 	world->add_obj(af);
 	_airfields.push_back(af);
 }

src/sim/aircraft.cpp

@@ -5,6 +5,13 @@ void dxd::sim::Aircraft::tick(float timestep, World *world)
 {
 	(void)world;
 
+	float target_angle = vec2_angle(_target - _position);
+	float target_deviation = target_angle - _direction;
+
+	target_deviation = normalize_angle_diff(target_deviation);
+
+	_direction += SDL_clamp(target_deviation, -_MAX_TURN_RATE, _MAX_TURN_RATE) * timestep;
+	_direction = normalize_angle(_direction);
 	_position = _position + polar_to_vec2(_direction, _speed) * timestep;
 
 	if (--_trail_cooldown == 0)
@@ -19,4 +26,7 @@ void dxd::sim::Aircraft::draw(Renderer *rend)
 	rend->color(255, 255, 255, 255);
 	rend->box(_position, 1);
 	rend->line(_position, _position + polar_to_vec2(_direction, 3));
+
+	rend->color(255, 64, 64, 255);
+	rend->diamond(_target, 1);
 }

src/sim/aircraft.hpp

@@ -12,14 +12,16 @@ private:
 	vec2 _position;
 	float _direction;
 	float _speed;
+	vec2 _target;
 	int _trail_cooldown;
 
 	const int _TRAIL_DELAY = 60;
 	const int _TRAIL_DURATION = 420;
+	const float _MAX_TURN_RATE = 0.5f;
 
 public:
-	Aircraft(vec2 position, float direction, float speed)
+	Aircraft(vec2 position, float direction, float speed, vec2 target)
-		: _position(position), _direction(direction), _speed(speed)
+		: _position(position), _direction(direction), _speed(speed), _target(target)
 	{
 		_trail_cooldown = _TRAIL_DELAY;
 	}

src/sim/airfield.cpp

@@ -13,9 +13,13 @@ void dxd::sim::Airfield::tick(float timestep, World *world)
 
 	if (--_next_spawn == 0)
 	{
-		Aircraft *af = new Aircraft(_position, SDL_randf() * 2 * M_PIf, 5.0f);
+		vec2 pos = _position + polar_to_vec2(_rw_heading, _WR_LENGTH+0.5);
+		//vec2 tgt = _position + polar_to_vec2(SDL_randf()*2*M_PIf, 30);
+		vec2 tgt = _position + polar_to_vec2(0, 30);
+		Aircraft *af = new Aircraft(pos, _rw_heading, 5.0f, tgt);
 		world->add_obj(af);
-		_next_spawn = _MIN_TAKEOFF_DELAY + SDL_rand(_MAX_TAKEOFF_DELAY - _MIN_TAKEOFF_DELAY);
+		//_next_spawn = _MIN_TAKEOFF_DELAY + SDL_rand(_MAX_TAKEOFF_DELAY - _MIN_TAKEOFF_DELAY);
+		_next_spawn = 99999999;
 	}
 }
 
@@ -24,4 +28,9 @@ void dxd::sim::Airfield::draw(Renderer *rend)
 	rend->color(127, 127, 127, 255);
 	rend->rect(_position, 5);
 	rend->diamond(_position, 5);
+
+	rend->color(64, 64, 255, 255);
+	vec2 a = _position + polar_to_vec2(_rw_heading, +_WR_LENGTH);
+	vec2 b = _position + polar_to_vec2(_rw_heading, -_WR_LENGTH);
+	rend->line(a, b);
 }

src/sim/airfield.hpp

@@ -14,14 +14,17 @@ private:
 	vec2 _position;
 	int _ttl;
 	int _next_spawn;
+	float _rw_heading;
 
 	const int _MIN_TAKEOFF_DELAY = 240;
 	const int _MAX_TAKEOFF_DELAY = 600;
+	const int _WR_LENGTH = 6;
 
 public:
-	Airfield(vec2 position, int ttl) : _position(position), _ttl(ttl)
+	Airfield(vec2 position, int ttl, float rw_heading)
+		: _position(position), _ttl(ttl), _rw_heading(rw_heading)
 	{
-		_next_spawn = 30;
+		_next_spawn = _MIN_TAKEOFF_DELAY;
 	}
 
 	void tick(float timestep, World *world) override;