From 1b39b8aaf6be5be56530979044fb893a5b51b489 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Sun, 13 Nov 2022 00:20:42 +0100
Subject: Implemented dumb keep-at-range behaviour

---
 battles/CMakeLists.txt      |  1 +
 battles/src/BaseBattle.cpp  | 17 +++++++++----
 battles/src/BaseBattle.h    |  2 ++
 battles/src/TeamManager.cpp | 60 +++++++++++++++++++++++++++++++++++++++++++++
 battles/src/TeamManager.h   | 31 +++++++++++++++++++++++
 5 files changed, 106 insertions(+), 5 deletions(-)
 create mode 100644 battles/src/TeamManager.cpp
 create mode 100644 battles/src/TeamManager.h

diff --git a/battles/CMakeLists.txt b/battles/CMakeLists.txt
index 261edd7..3aa0840 100644
--- a/battles/CMakeLists.txt
+++ b/battles/CMakeLists.txt
@@ -6,6 +6,7 @@ add_library(
 	src/Point.cpp
 	src/RandomSpawner.cpp
 	src/scenarios.cpp
+	src/TeamManager.cpp
 )
 target_include_directories(
 	${PROJECT_NAME}
diff --git a/battles/src/BaseBattle.cpp b/battles/src/BaseBattle.cpp
index 8527a56..92ab351 100644
--- a/battles/src/BaseBattle.cpp
+++ b/battles/src/BaseBattle.cpp
@@ -30,6 +30,7 @@ BaseBattle::BaseBattle(const Scenario& scenario) :
 		_registry.emplace<Transform>(entity, spawner.get(ship.team));
 		_registry.emplace<FloatingMovement>(entity, 0.4);
 		_registry.emplace<AIState>(entity, Point{0.0, 0.0});
+		manager.add(ship.team, entity);  // registry supports on construction events
 	}
 }
 
@@ -44,16 +45,22 @@ BaseBattle::registry()
 void
 BaseBattle::update(const float dt)
 {
-	auto view = _registry.view<Transform, AIState, FloatingMovement>();
-	for (auto&& [entity, transform, state, movement] : view.each()) {
+	auto view = _registry.view<Team, Transform, AIState, FloatingMovement>();
+	for (auto&& [entity, team, transform, state, movement] : view.each()) {
+		if (!_registry.valid(state.target))
+			state.target = manager.random((team.id + 1) % 2);
+		const auto target = _registry.get<Transform>(state.target);
 		const double speed = movement.speed * dt;
-		const Point diff = (state.destination - transform.position);
-		if (diff.magnitude() > speed) {
-			const Point eff = diff.normalized().scale(speed);
+		const Point diff = target.position - transform.position;
+		const Point dest = target.position - diff.normalized();
+		const Point move = dest - transform.position;
+		if (move.magnitude() > speed) {
+			const Point eff = move.normalized().scale(speed);
 			transform.position.x += eff.x;
 			transform.position.y += eff.y;
 		}
 	}
+	manager.clear(_registry);  // registry supports on destructions events
 }
 
 
diff --git a/battles/src/BaseBattle.h b/battles/src/BaseBattle.h
index b47ebd7..124d1b7 100644
--- a/battles/src/BaseBattle.h
+++ b/battles/src/BaseBattle.h
@@ -6,6 +6,7 @@
 #include <kurator/battles/Scenario.h>
 
 #include "RandomSpawner.h"
+#include "TeamManager.h"
 
 
 namespace kurator
@@ -23,6 +24,7 @@ public:
 private:
 	entt::registry _registry;
 	RandomSpawner spawner;
+	TeamManager manager;
 };
 
 
diff --git a/battles/src/TeamManager.cpp b/battles/src/TeamManager.cpp
new file mode 100644
index 0000000..e4afeb3
--- /dev/null
+++ b/battles/src/TeamManager.cpp
@@ -0,0 +1,60 @@
+#include "TeamManager.h"
+
+#include <algorithm>
+#include <random>
+#include <utility>
+#include <vector>
+
+#include <entt/entity/registry.hpp>
+
+
+namespace kurator
+{
+namespace battles
+{
+
+
+TeamManager::TeamManager() :
+	teams {},
+	generator {std::random_device{}()}
+{
+}
+
+
+void
+TeamManager::add(int team, entt::entity entity)
+{
+	for (int i = teams.size(); i < team + 1; ++i)
+		teams.emplace_back();
+	teams.at(team).push_back(std::move(entity));
+}
+
+
+TeamManager::Team
+TeamManager::get(int team) const
+{
+	return teams.at(team);
+}
+
+
+entt::entity
+TeamManager::random(int team)
+{
+	auto& members = teams.at(team);
+	std::uniform_int_distribution<Team::size_type> uniform{0, members.size() - 1};
+	return members.at(uniform(generator));
+}
+
+
+void
+TeamManager::clear(entt::registry& registry)
+{
+	for (auto& members : teams) {
+		auto is_valid = [&registry](entt::entity entity){ return !registry.valid(entity); };
+		members.erase(std::remove_if(members.begin(), members.end(), is_valid), members.end());
+	}
+}
+
+
+}  // namespace battles
+}  // namespace kurator
diff --git a/battles/src/TeamManager.h b/battles/src/TeamManager.h
new file mode 100644
index 0000000..384d9ee
--- /dev/null
+++ b/battles/src/TeamManager.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <random>
+#include <vector>
+
+#include <entt/entity/registry.hpp>
+
+
+namespace kurator
+{
+namespace battles
+{
+
+
+class TeamManager
+{
+public:
+	using Team = std::vector<entt::entity>;
+	TeamManager();
+	void add(int team, entt::entity entity);
+	Team get(int team) const;
+	entt::entity random(int team);
+	void clear(entt::registry& registry);
+private:
+	std::vector<Team> teams;
+	std::mt19937 generator;
+};
+
+
+}  // namespace battles
+}  // namespace kurator
-- 
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