Allow to pick up dropped items.

source/Game.cpp

@@ -173,7 +173,7 @@ Game::keyUp(const sf::Event& event) {
 		mPlayer->setDirection(Player::Direction::RIGHT, true);
 		break;
 	case sf::Keyboard::F:
-		mPlayer->swapGadgets();
+		mPlayer->pickUpItem();
 		break;
 	default:
 		break;

source/World.cpp

@@ -41,13 +41,20 @@ World::insertCharacter(std::shared_ptr<Character> character) {
 	insert(character);
 }
 
+void
+World::remove(std::shared_ptr<Sprite> drawable) {
+	Sprite::Category cat = drawable->getCategory();
+	auto item = std::find(mDrawables[cat].begin(), mDrawables[cat].end(), drawable);
+	mDrawables[cat].erase(item);
+}
+
 /**
  * Returns all characters that are within maxDistance from position.
  */
 std::vector<std::shared_ptr<Character> >
 		World::getCharacters(const sf::Vector2f& position, float maxDistance) const {
 	std::vector<std::shared_ptr<Character> > visible;
-	for (auto it : mCharacters) {
+	for (const auto& it : mCharacters) {
 		if (position == it->getPosition())
 			continue;
 		if (thor::squaredLength(position - it->getPosition()) <=
@@ -88,7 +95,7 @@ void
 World::applyMovement(std::shared_ptr<Sprite> sprite, int elapsed) {
 	sf::Vector2f offset = sprite->getSpeed() * (elapsed / 1000.0f);
 	for (auto w = mDrawables.begin(); w != mDrawables.end(); w++) {
-		for (auto& other : w->second) {
+		for (const auto& other : w->second) {
 			if (sprite == other)
 				continue;
 			// Ignore anything that is filtered by masks.
@@ -135,7 +142,7 @@ World::draw(sf::RenderTarget& target, sf::RenderStates states) const {
 	screen.left += target.getView().getCenter().x - target.getView().getSize().x / 2;
 	screen.top += target.getView().getCenter().y - target.getView().getSize().y / 2;
 	for (auto v = mDrawables.begin(); v != mDrawables.end(); v++) {
-		for (auto item : v->second) {
+		for (const auto& item : v->second) {
 			if (item->isInside(screen))
 				target.draw(static_cast<sf::Drawable&>(*item), states);
 		}
@@ -184,3 +191,21 @@ World::raycast(const sf::Vector2f& lineStart,
 	}
 	return true;
 }
+
+/**
+ * Returns the item closest to position after linear search.
+ */
+std::shared_ptr<Item>
+World::getNearestItem(const sf::Vector2f& position) const {
+	std::shared_ptr<Item> closest;
+	float distance = std::numeric_limits<float>::max();
+	for (const auto& v : mDrawables) {
+		for (const auto& d : v.second) {
+			std::shared_ptr<Item> converted = std::dynamic_pointer_cast<Item>(d);
+			if (converted.get() != nullptr &&
+					thor::squaredLength(converted->getPosition() - position) < distance)
+				closest = converted;
+		}
+	}
+	return closest;
+}

source/World.h

@@ -24,12 +24,14 @@ class World : public sf::Drawable {
 public:
 	void insert(std::shared_ptr<Sprite> drawable);
 	void insertCharacter(std::shared_ptr<Character> character);
+	void remove(std::shared_ptr<Sprite> drawable);
 	void step(int elapsed);
 	void think(int elapsed);
 	std::vector<std::shared_ptr<Character> >
 			getCharacters(const sf::Vector2f& position, float maxDistance) const;
 	bool raycast(const sf::Vector2f& lineStart,
 			const sf::Vector2f& lineEnd) const;
+	std::shared_ptr<Item> getNearestItem(const sf::Vector2f& position) const;
 
 private:
 

source/abstract/Character.cpp

@@ -18,6 +18,7 @@
 
 const float Character::VISION_DISTANCE = 500.0f;
 const float Character::POINT_REACHED_DISTANCE = 1.0f;
+const float Character::ITEM_PICKUP_MAX_DISTANCE_SQUARED = 2500.0f;
 
 /**
  * Saves pointer to this instance in static var for think().
@@ -259,7 +260,34 @@ Character::getRightGadgetName() const {
 	return mRightGadget->getName();
 }
 
+/**
+ * Picks up the nearest weapon or gadget, and drops the active weapon (or right gadget).
+ *
+ * If no item is nearby, gadgets are swapped instead.
+ */
 void
-Character::swapGadgets() {
+Character::pickUpItem() {
+	std::shared_ptr<Item> item = mWorld.getNearestItem(getPosition());
+	if (item != nullptr && thor::squaredLength(item->getPosition() - getPosition()) <=
+            ITEM_PICKUP_MAX_DISTANCE_SQUARED) {
+		std::shared_ptr<Weapon> weapon = std::dynamic_pointer_cast<Weapon>(item);
+		if (weapon != nullptr) {
+			mWorld.insert(mActiveWeapon);
+			mActiveWeapon->drop(getPosition());
+			mActiveWeapon = weapon;
+			mActiveWeapon->setHolder(*this);
+		}
+		std::shared_ptr<Gadget> gadget = std::dynamic_pointer_cast<Gadget>(item);
+		if (gadget != nullptr) {
+			mWorld.insert(mRightGadget);
+			mRightGadget->drop(getPosition());
+			mRightGadget = mLeftGadget;
+			mLeftGadget = gadget;
+		}
+		// TODO: implement (or just make invisible?)
+		mWorld.remove(item);
+	}
+	else {
 		std::swap(mLeftGadget, mRightGadget);
 	}
+}

source/abstract/Character.h

@@ -63,7 +63,7 @@ protected:
 	void useRightGadget();
 	std::string getLeftGadgetName() const;
 	std::string getRightGadgetName() const;
-	void swapGadgets();
+	void pickUpItem();
 
 protected:
 
@@ -76,6 +76,8 @@ private:
 	/// Distance to a path point where it will be considered as reached (to
 	/// avoid floating point equality check).
 	static const float POINT_REACHED_DISTANCE;
+	/// Maximum distance from character where an item can be picked up.
+	static const float ITEM_PICKUP_MAX_DISTANCE_SQUARED;
 	friend class World;
 	World& mWorld;
 	Pathfinder& mPathfinder;

source/items/Weapon.cpp

@@ -16,7 +16,7 @@
 Weapon::Weapon(World& world, Character& holder, const Yaml& config) :
 		Item(sf::Vector2f(80, 30), "weapon.png"),
 		mWorld(world),
-		mHolder(holder),
+		mHolder(&holder),
 		mName(config.get("name", std::string())),
 		mProjectile(config.get("bullet", std::string("bullet.yaml"))),
 		mDamage(config.get("damage", 0)),
@@ -142,6 +142,11 @@ Weapon::cancelReload() {
 	mTimer.restart(sf::milliseconds(mFireInterval));
 }
 
+void
+Weapon::setHolder(Character& holder) {
+    mHolder = &holder;
+}
+
 /**
  * Creates a new projectile and inserts it into the world.
  *
@@ -149,18 +154,18 @@ Weapon::cancelReload() {
  */
 void
 Weapon::insertProjectile(float angle) {
-	sf::Vector2f offset(mHolder.getDirection() * mHolder.getRadius());
+	sf::Vector2f offset(mHolder->getDirection() * mHolder->getRadius());
 
-	float spread = (mHolder.getSpeed() == sf::Vector2f())
+	float spread = (mHolder->getSpeed() == sf::Vector2f())
 			? mSpread
 			: mSpreadMoving;
 	std::uniform_real_distribution<float> distribution(- spread, spread);
 	angle += distribution(mGenerator) + 90.0f;
 
-	sf::Vector2f direction(thor::rotatedVector(mHolder.getDirection(), angle));
+	sf::Vector2f direction(thor::rotatedVector(mHolder->getDirection(), angle));
 
-	std::shared_ptr<Sprite> projectile(new Bullet(mHolder.getPosition() + offset,
+	std::shared_ptr<Sprite> projectile(new Bullet(mHolder->getPosition() + offset,
-			mHolder, direction, mProjectile, mProjectileSpeed,
+			*mHolder, direction, mProjectile, mProjectileSpeed,
 			mDamage, mMaxRange));
 	mWorld.insert(projectile);
 }

source/items/Weapon.h

@@ -35,6 +35,7 @@ public:
 	std::string getName() const;
 	void reload();
 	void cancelReload();
+	void setHolder(Character& holder);
 
 private:
 	void fire();
@@ -42,7 +43,8 @@ private:
 
 private:
 	World& mWorld;
-	Character& mHolder;
+	/// Non-owning pointer instead of reference to allow reassigning.
+	Character* mHolder;
 
 	thor::Timer mTimer;
 	const std::string mName;

source/sprites/Player.h

@@ -50,7 +50,7 @@ public:
 	using Character::getHealth;
 	using Character::getLeftGadgetName;
 	using Character::getRightGadgetName;
-	using Character::swapGadgets;
+	using Character::pickUpItem;
 
 private:
 	void onThink(int elapsed) override;