From 52b0bdaba5b38790d144bf1e800ea34be937ded0 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Thu, 4 May 2023 00:07:51 +0200
Subject: Refactored Actions to be owned by registry

Registry is now also responsible for switching between the actions and
each action is expected to have one system. Technically an std::variant
could be used here, but let's wait a bit and see how this part evolves.
---
 kurator/src/inspect.cpp      |  9 ++++++++
 sim/include/kurator/sim/ai.h | 13 ++++++-----
 sim/src/BaseSimulation.cpp   |  3 ++-
 sim/src/ai.cpp               | 55 +++++++++++++-------------------------------
 sim/src/ai.h                 |  3 ++-
 5 files changed, 36 insertions(+), 47 deletions(-)

diff --git a/kurator/src/inspect.cpp b/kurator/src/inspect.cpp
index ab52bb8..d49a917 100644
--- a/kurator/src/inspect.cpp
+++ b/kurator/src/inspect.cpp
@@ -54,6 +54,7 @@ InspectionWindow::show()
 			inspect<sim::FloatingMovement>(*it);
 			inspect<sim::HitPoints>(*it);
 			inspect<sim::AIShip>(*it);
+			inspect<sim::KeepAtRange>(*it);
 			inspect<sim::Turret>(*it);
 			inspect<TurretVisuals>(*it);
 			inspect<AIVisuals>(*it);
@@ -184,6 +185,14 @@ inspect(entt::handle&, sim::AIShip& ai)
 
 template <>
 void
+inspect(entt::handle&, sim::KeepAtRange& action)
+{
+	ImGui::InputDouble("Keep At Range", &action.distance, 0, 0, "%.1f");
+}
+
+
+template <>
+void
 inspect(entt::handle&, AIVisuals& visuals)
 {
 	ImGui::Checkbox("Show Target", &visuals.show_target);
diff --git a/sim/include/kurator/sim/ai.h b/sim/include/kurator/sim/ai.h
index 0ffa1cc..4953d4f 100644
--- a/sim/include/kurator/sim/ai.h
+++ b/sim/include/kurator/sim/ai.h
@@ -1,7 +1,5 @@
 #pragma once
 
-#include <functional>
-
 #include <entt/entt.hpp>
 
 #include <kurator/engine/Point.h>
@@ -15,16 +13,19 @@ namespace sim
 {
 
 
-using Action = std::function<void()>;
-
-
 struct AIShip
 {
-	Action action;
 	engine::Point destination;
 	entt::entity target = entt::null;
 };
 
 
+struct KeepAtRange
+{
+	double distance;
+	entt::entity target = entt::null;
+};
+
+
 }  // namespace sim
 }  // namespace kurator
diff --git a/sim/src/BaseSimulation.cpp b/sim/src/BaseSimulation.cpp
index 2731c67..ffd43f9 100644
--- a/sim/src/BaseSimulation.cpp
+++ b/sim/src/BaseSimulation.cpp
@@ -16,6 +16,7 @@ namespace sim
 
 BaseSimulation::BaseSimulation(State& ctx)
 {
+	setup_ai_components(ctx);
 	manager.extend(ctx);
 }
 
@@ -24,7 +25,7 @@ void
 BaseSimulation::operator()(State& ctx)
 {
 	pick_random_targets(ctx, manager);
-	take_actions(ctx);
+	keep_at_range(ctx);
 	FloatingMovement::update(ctx);
 	update_turrets(ctx);
 	shoot_at_targets(ctx);
diff --git a/sim/src/ai.cpp b/sim/src/ai.cpp
index 7a0f637..7b6f700 100644
--- a/sim/src/ai.cpp
+++ b/sim/src/ai.cpp
@@ -1,7 +1,6 @@
 #include "ai.h"
 
 #include <algorithm>
-#include <utility>
 
 #include <entt/entt.hpp>
 
@@ -21,37 +20,11 @@ namespace sim
 static double find_worst_range(State& ctx, entt::entity ship);
 
 
-class KeepAtRange
+void
+setup_ai_components(State&)
 {
-public:
-	KeepAtRange(State& ctx_, AIShip& ai_, entt::entity self_, entt::entity target_, double distance_) :
-		ctx {ctx_},
-		ai {ai_},
-		self {std::move(self_)},
-		target {std::move(target_)},
-		distance {distance_}
-	{
-	}
-
-	void operator()()
-	{
-		if (!ctx.registry.valid(target)) {
-			if (ctx.registry.valid(ai.target))
-				ai.action = KeepAtRange(ctx, ai, self, ai.target, distance);
-			return;
-		}
-		const auto here = ctx.registry.get<Transform>(self).position;
-		const auto there = ctx.registry.get<Transform>(target).position;
-		const auto offset = there - here;
-		ai.destination = there - offset.normalized().scale(distance);
-	}
-private:
-	State& ctx;
-	AIShip& ai;
-	entt::entity self;
-	entt::entity target;
-	double distance;
-};
+	// e.g., remove other actions if new one is inserted.
+}
 
 
 void
@@ -59,21 +32,25 @@ pick_random_targets(State& ctx, TeamManager& manager)
 {
 	auto view = ctx.registry.view<Team, AIShip>();
 	for (auto&& [entity, team, ai] : view.each()) {
-		if (!ctx.registry.valid(ai.target))
+		if (!ctx.registry.valid(ai.target)) {
 			ai.target = manager.random(team.id);
-		if (!ai.action)
-			ai.action = KeepAtRange(ctx, ai, entity, ai.target, find_worst_range(ctx, entity));
+			ctx.registry.emplace_or_replace<KeepAtRange>(entity, find_worst_range(ctx, entity), ai.target);
+		}
 	}
 }
 
 
 void
-take_actions(State& ctx)
+keep_at_range(State& ctx)
 {
-	auto view = ctx.registry.view<AIShip>();
-	for (auto&& [_, ai] : view.each()) {
-		if (ai.action)
-			ai.action();
+	auto view = ctx.registry.view<AIShip, KeepAtRange>();
+	for (auto&& [entity, ai, action] : view.each()) {
+		if (!ctx.registry.valid(action.target))
+			continue;
+		const auto here = ctx.registry.get<Transform>(entity).position;
+		const auto there = ctx.registry.get<Transform>(action.target).position;
+		const auto offset = there - here;
+		ai.destination = there - offset.normalized().scale(action.distance);
 	}
 }
 
diff --git a/sim/src/ai.h b/sim/src/ai.h
index d1e9c29..e306be1 100644
--- a/sim/src/ai.h
+++ b/sim/src/ai.h
@@ -12,8 +12,9 @@ namespace sim
 {
 
 
+void setup_ai_components(State& ctx);
 void pick_random_targets(State& ctx, TeamManager& manager);
-void take_actions(State& ctx);
+void keep_at_range(State& ctx);
 void shoot_at_targets(State& ctx);
 
 
-- 
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