Vastly improve following.

2 files changed, 67 insertions, 44 deletions

diff --git a/src/common.hpp b/src/common.hpp
index 7221b44..87706c8 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -266,13 +266,16 @@ namespace interface {
 		float em;
 
 		struct {
+			v2f_t zero_point_s = v2f_t(0, 0);
 			v2f_t center = v2f_t(0, 0);
-			int target_zoom = 3;
-			float zoom = 3.0f;
+
+			int zoom = 3;
+			float zoom_s = 3.0f;
+
 			bool panning = false;
 			sf::Vector2f pan_ref;
+
 			bool following = true;
-			v2f_t follow_center = v2f_t(0, 0);
 		} camera;
 
 		struct {
@@ -290,6 +293,8 @@ namespace interface {
 		double perf_hist[10] = {0};
 		size_t perf_hist_index = 0;
 
+		void start_following(void);
+		void stop_following(void);
 	public:
 		state_t(sf::RenderWindow *window_, game::state_t *game);
 		void tick(double dt);
@@ -408,7 +413,14 @@ T bilerp(T a, T b, T c, T d, T x, T y)
 	return lerp(ab, cd, y);
 }
 
-static inline float expfade(float a, float b, float l, float dt)
+template <typename T>
+static inline void expfade(T *a, T b, T l, T dt)
+{
+	*a = b + (*a - b) * exp(-l * dt);
+}
+
+template <typename T, size_t N>
+static inline void expfade(vec_t<T, N> *a, vec_t<T, N>  b, float l, float dt)
 {
-	return b + (a - b) * exp(-l * dt);
+	*a = b + (*a - b) * exp(-l * dt);
 }
diff --git a/src/game/interface.cpp b/src/game/interface.cpp
index 1300e95..7697a22 100644
--- a/src/game/interface.cpp
+++ b/src/game/interface.cpp
@@ -35,56 +35,72 @@ static sf::Vector2f compute_pan(sf::RenderWindow *window, sf::Vector2f pan_ref)
 	return -(vmouse - pan_ref);
 }
 
+void state_t::start_following(void)
+{
+	camera.following = true;
+	camera.zero_point_s = camera.center;
+	camera.center = v2f_t(0, 0);
+	print(text::get(text::FOLLOWING_ON));
+}
+
+void state_t::stop_following(void)
+{
+	camera.following = false;
+	camera.center += camera.zero_point_s;
+	camera.zero_point_s = v2f_t(0, 0);
+	print(text::get(text::FOLLOWING_OFF));
+}
+
 void state_t::tick(double dt)
 {
-	sf::Vector2u size;
+	vec_t<int, 2> window_size;
 	sf::Event event;
-	sf::Vector2f view_size;
-	v2f_t wmouse; // Mouse position in world space;
+
+	v2f_t view_size;
 	v2f_t follow_center(0, 0), view_center, pan_delta;
 	float view_scale;
+	v2f_t wmouse; // Mouse position in world space;
 
-	size = window->getSize();
+	window_size = window->getSize();
 
-	camera.zoom = expfade(camera.zoom, camera.target_zoom, 15, dt);
-	view_scale = 4.5 * exp(camera.zoom * 0.12);
-	if (size.x < size.y) {
-		view_size.y = view_scale;
-		view_size.x = view_scale * size.x / size.y;
+	expfade<float>(&camera.zoom_s, camera.zoom, 15, dt);
+	view_scale = 4.5 * exp(camera.zoom_s * 0.12);
+	if (window_size[0] < window_size[1]) {
+		view_size[1] = view_scale;
+		view_size[0] = view_scale * window_size[0] / window_size[1];
 	} else {
-		view_size.x = view_scale;
-		view_size.y = view_scale * size.y / size.x;
+		view_size[0] = view_scale;
+		view_size[1] = view_scale * window_size[1] / window_size[0];
 	}
 
-	if (!game->selected_units.size() && camera.following) {
-		camera.center = camera.follow_center;
-		print(text::get(text::FOLLOWING_OFF));
-		camera.following = false;
-	}
+	if (!game->selected_units.size() && camera.following)
+		stop_following();
 
 	if (camera.following) {
+		float limit;
+
 		for (entity_t *ent : game->selected_units)
 			follow_center += ent->render_bounds.center();
 		follow_center /= game->selected_units.size();
 
-		camera.follow_center[0] = expfade(camera.follow_center[0], follow_center[0], dt, 25);
-		camera.follow_center[1] = expfade(camera.follow_center[1], follow_center[1], dt, 25);
-	}
-
-	view_center = camera.center;
+		expfade<float, 2>(&camera.zero_point_s, follow_center, 15, dt);
 
-	if (camera.following)
-		view_center += camera.follow_center;
+		limit = view_scale * 0.2f;
+		if (camera.center.len() > limit * 2.0f)
+			stop_following();
+		else if (camera.center.len() > limit)
+			expfade<float, 2>(&camera.center, camera.center.norm() * limit, 3, dt);
+	}
 
+	view_center = camera.zero_point_s + camera.center;
 	window->setView(sf::View(view_center, view_size));
 
 	if (camera.panning) {
 		pan_delta = compute_pan(window, camera.pan_ref);
 		view_center += compute_pan(window, camera.pan_ref);
+		window->setView(sf::View(view_center, view_size));
 	}
 
-	window->setView(sf::View(view_center, view_size));
-
 	wmouse = window->mapPixelToCoords(sf::Mouse::getPosition(*window));
 
 	while (window->pollEvent(event)) {
@@ -134,11 +150,11 @@ void state_t::tick(double dt)
 			break;
 
 		case sf::Event::MouseWheelScrolled:
-			camera.target_zoom -= event.mouseWheelScroll.delta;
-			if (camera.target_zoom < 0)
-				camera.target_zoom = 0;
-			if (camera.target_zoom > 17)
-				camera.target_zoom = 17;
+			camera.zoom -= event.mouseWheelScroll.delta;
+			if (camera.zoom < 0)
+				camera.zoom = 0;
+			if (camera.zoom > 17)
+				camera.zoom = 17;
 			break;
 
 		case sf::Event::KeyPressed:
@@ -152,15 +168,10 @@ void state_t::tick(double dt)
 				break;
 
 			case sf::Keyboard::Key::F:
-				camera.following ^= 1;
-
-				if (!camera.following) {
-					camera.center = view_center;
-					print(text::get(text::FOLLOWING_OFF));
-				} else {
-					camera.center = v2f_t(0, 0);
-					print(text::get(text::FOLLOWING_ON));
-				}
+				if (camera.following)
+					stop_following();
+				else
+					start_following();
 				break;
 
 			case sf::Keyboard::Key::H: