feat: Very broken trigonometry but planes turn

src/math.hpp

@@ -9,6 +9,7 @@
 
 typedef struct vec2 { float x, y; } vec2;
 typedef struct vec2i { int x, y; } vec2i;
+typedef struct polar_t { float angle, length; } polar_t;
 
 static const vec2 vec2_zero = { 0, 0 };
 static const vec2 vec2_one = { 1, 1 };
@@ -102,8 +103,29 @@ static vec2 max2(vec2 const &a, vec2 const &b)
 
 static vec2 polar_to_vec2(const float angle, const float len)
 {
+    // 0 (north) up
     return {
         .x = len * sinf(angle),
         .y = len * cosf(angle)
     };
 }
+
+static polar_t vec2_to_polar(const vec2 v)
+{
+    // 0 (north) up
+    if (v.x == 0)
+        return {
+            .angle = (v.y > 0) ? 0 : M_PIf,
+            .length = abs(v.y)
+        };
+
+    polar_t ret = {
+        .angle = atanf(v.x / v.y) + (v.y > 0 ? 0 : M_PIf),
+        .length = norm(v)
+    };
+
+    if (ret.angle < 0)
+        ret.angle += 2 * M_PIf;
+
+    return ret;
+}

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 +5,16 @@ void dxd::sim::Aircraft::tick(float timestep, World *world)
 {
 	(void)world;
 
+	float target_direction = vec2_to_polar(_target - _position).angle;
+	float target_deviation = target_direction - _direction;
+	//TODO: Fix this normalization mess
+	if (target_deviation > M_PIf)
+	{
+		target_deviation -= 2 * M_PIf;
+	}
+	printf("%0.2f %.2f %0.2f\n", target_direction, target_deviation, target_direction - _direction);
+
+	_direction += SDL_clamp(target_deviation, -_MAX_TURN_RATE, _MAX_TURN_RATE) * timestep;
 	_position = _position + polar_to_vec2(_direction, _speed) * timestep;
 
 	if (--_trail_cooldown == 0)

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)
-		: _position(position), _direction(direction), _speed(speed)
+	Aircraft(vec2 position, float direction, float speed, vec2 target)
+		: _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, 80);
+		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;