feat: add vehicle and kinematics systems

Signed-off-by: szdytom <szdytom@qq.com>

core/CMakeLists.txt

@@ -1,7 +1,12 @@
 cmake_minimum_required(VERSION 3.27)
 
 set(ISTD_CORE_SRC
+	src/devices/vehicle.cpp
+	src/device.cpp
 	src/room.cpp
+	src/system.cpp
+	src/unit.cpp
+	src/world.cpp
 )
 
 add_library(istd_core STATIC ${ISTD_CORE_SRC})

core/include/istd_core/device.h

@@ -30,13 +30,14 @@ public:
 
 struct DevicePrototype {
 	std::string_view name;
-	RegSetStrategy *reg_set_strategy; // life cycle: static
+	const RegSetStrategy *reg_set_strategy; // life cycle: static
 	std::uint32_t mass;
-	ItemPort input_n, output_n;       // number of input/output ports
+	ItemType item;              // item type this device is built from
+	ItemPort input_n, output_n; // number of input/output ports
 };
 
 struct DevicePrototypeComponent {
-	DevicePrototype *prototype; // life cycle: static
+	const DevicePrototype *prototype; // life cycle: static
 };
 
 struct DeviceIdComponent {
@@ -49,18 +50,27 @@ struct DeviceBuilder {
 		World &world, entt::entity unit, DeviceId device_id
 	) const
 		= 0;
+
+	// No virtual destructor: static lifetime and no member variables is the
+	// intended use case
 };
 
-struct DeviceBuilderRegistry {
+class DeviceBuilderRegistry {
-	static DeviceBuilderRegistry &instance();
+public:
+	static DeviceBuilderRegistry &instance() noexcept;
+
+	void register_builder(ItemType item, const DeviceBuilder *builder);
 
-	void register_builder(Item item, DeviceBuilder *builder);
 	entt::entity build(
-		World &world, Item item, entt::entity unit, DeviceId device_id
+		World &world, ItemType item, entt::entity unit, DeviceId device_id
 	) const;
 
+	struct Registar {
+		Registar(ItemType item, const DeviceBuilder *builder);
+	};
+
 private:
-	SmallMap<Item, DeviceBuilder *> builders_;
+	SmallMap<ItemType, const DeviceBuilder *> builders_;
 };
 
 } // namespace istd

core/include/istd_core/devices/vehicle.h

@@ -0,0 +1,23 @@
+#ifndef ISTD_CORE_DEVICE_VIHICLE_H
+#define ISTD_CORE_DEVICE_VIHICLE_H
+
+#include <entt/entt.hpp>
+#include <string_view>
+
+namespace istd {
+
+struct VehiclePrototype {
+	std::string_view name;
+	std::uint32_t ideal_working_mass;
+	float max_speed; // in tile/tick
+};
+
+struct VehicleComponent {
+	const VehiclePrototype *prototype; // life cycle: static
+	float heading; // in radians, 0 is South, counter-clockwise
+	float speed;   // percentage of max speed, 0.0 to 1.0
+};
+
+} // namespace istd
+
+#endif

core/include/istd_core/item.h

@@ -16,7 +16,7 @@ consteval std::uint32_t id_string(const char *str) {
 	return id;
 }
 
-enum class Item : std::uint32_t {
+enum class ItemType : std::uint32_t {
 	Null = 0,
 
 	// Materials

core/include/istd_core/unit.h

@@ -35,6 +35,16 @@ struct DeviceStackComponent {
 	std::vector<entt::entity> devices;
 };
 
+/**
+ * @brief Flag component to indicate that the unit is on the ground.
+ */
+struct OnGroundFlag {};
+
+/**
+ * @brief Flag component to indicate that the unit is in the air.
+ */
+struct AirborneFlag {};
+
 } // namespace istd
 
 #endif

core/src/device.cpp

@@ -15,22 +15,30 @@ bool RegSetStrategy::write(
 	return false;
 }
 
-DeviceBuilderRegistry &DeviceBuilderRegistry::instance() {
+DeviceBuilderRegistry &DeviceBuilderRegistry::instance() noexcept {
 	static DeviceBuilderRegistry registry;
 	return registry;
 }
 
 void DeviceBuilderRegistry::register_builder(
-	Item item, DeviceBuilder *builder
+	ItemType item, const DeviceBuilder *builder
 ) {
 	builders_.insert(item, builder);
 }
 
 entt::entity DeviceBuilderRegistry::build(
-	World &world, Item item, entt::entity unit, DeviceId device_id
+	World &world, ItemType item, entt::entity unit, DeviceId device_id
 ) const {
 	auto builder = builders_[item];
-	return builder->build(world, unit, device_id);
+	auto entity = builder->build(world, unit, device_id);
+	world.registry.emplace<DeviceIdComponent>(entity, unit, device_id);
+	return entity;
+}
+
+DeviceBuilderRegistry::Registar::Registar(
+	ItemType item, const DeviceBuilder *builder
+) {
+	DeviceBuilderRegistry::instance().register_builder(item, builder);
 }
 
 } // namespace istd

core/src/devices/vehicle.cpp

@@ -0,0 +1,159 @@
+#include "istd_core/devices/vehicle.h"
+#include "istd_core/device.h"
+#include "istd_core/system.h"
+#include "istd_core/unit.h"
+
+namespace istd {
+namespace {
+
+// Vehicle register allocations:
+// 0: Vehicle speed (1 = 1 / 256 of max speed)
+// 1: Vehicle heading (1 = 1 / 256 pi)
+// 2: Vehicle x position (1 = 1 / 1024 tile) (read-only)
+// 3: Vehicle y position (1 = 1 / 1024 tile) (read-only)
+// 4: Device status / error code
+
+struct VehicleRegSetStrategy : public RegSetStrategy {
+	virtual bool read(
+		World &world, entt::entity entity, std::uint8_t reg_id,
+		std::uint32_t &value
+	) const noexcept override {
+		auto &reg = world.registry;
+		switch (reg_id) {
+		case 0: { // Vehicle speed
+			auto &vehicle = reg.get<const VehicleComponent>(entity);
+			value = static_cast<std::uint32_t>(vehicle.speed * 256.0f);
+			break;
+		}
+
+		case 1: { // Vehicle heading
+			auto &vehicle = reg.get<const VehicleComponent>(entity);
+			value = static_cast<std::uint32_t>(
+				(vehicle.heading / (2.0f * M_PI)) * 256.0f
+			);
+			break;
+		}
+
+		case 2: { // Vehicle x position
+			auto owner = reg.get<const DeviceIdComponent>(entity).unit;
+			auto pos = reg.get<const KinematicsComponent>(owner).position;
+			value = static_cast<std::uint32_t>(pos.x * 1024);
+			break;
+		}
+
+		case 3: { // Vehicle y position
+			auto owner = reg.get<const DeviceIdComponent>(entity).unit;
+			auto pos = reg.get<const KinematicsComponent>(owner).position;
+			value = static_cast<std::uint32_t>(pos.y * 1024);
+			break;
+		}
+
+		case 4:
+			// No error code for now, just return 0
+			value = 0;
+			break;
+
+		default:
+			return false; // Invalid register ID
+		}
+		return true;      // Read successful
+	}
+
+	virtual bool write(
+		World &world, entt::entity entity, std::uint8_t reg_id,
+		std::uint32_t value
+	) const noexcept override {
+		switch (reg_id) {
+		case 0: { // Vehicle speed
+			auto &vehicle = world.registry.get<VehicleComponent>(entity);
+			vehicle.speed = static_cast<float>(value) / 256.0f;
+			return true;
+		}
+		case 1: { // Vehicle heading
+			auto &vehicle = world.registry.get<VehicleComponent>(entity);
+			vehicle.heading = (static_cast<float>(value) / 256.0f)
+				* (2.0f * M_PI);
+			return true;
+		}
+		default:
+			return false; // Invalid register ID or read-only register
+		}
+	}
+};
+
+static const VehicleRegSetStrategy vehicle_reg_set_strategy;
+
+static const VehiclePrototype basic_vihicle_prototype = {
+	.name = "Basic Vehicle",
+	.ideal_working_mass = 7440,
+	.max_speed = 0.3f, // 1 tile per tick
+};
+
+static const DevicePrototype basic_vehicle_device_prototype = {
+	.name = "Basic Vehicle Device",
+	.reg_set_strategy = &vehicle_reg_set_strategy,
+	.mass = 3270,
+	.item = ItemType::BasicVehicleChassis,
+	.input_n = 0,
+	.output_n = 0,
+};
+
+struct BasicVehicleBuilder : public DeviceBuilder {
+	entt::entity build(
+		World &world, entt::entity unit, DeviceId device_id
+	) const override {
+		auto entity = world.registry.create();
+
+		world.registry.emplace<DevicePrototypeComponent>(
+			entity, &basic_vehicle_device_prototype
+		);
+
+		world.registry.emplace<VehicleComponent>(
+			entity, &basic_vihicle_prototype, 0.0f, 0.0f
+		);
+
+		return entity;
+	}
+};
+
+static const BasicVehicleBuilder basic_vehicle_builder;
+static const DeviceBuilderRegistry::Registar basic_vehicle_registrar(
+	ItemType::BasicVehicleChassis, &basic_vehicle_builder
+);
+
+struct VehicleVelocitySystem : public System {
+	void tick(World &world) const noexcept override {
+		auto &reg = world.registry;
+		reg.view<const VehicleComponent, const DeviceIdComponent>().each(
+			[&reg](
+				entt::entity entity, const VehicleComponent &vehicle,
+				const DeviceIdComponent &device_id
+			) {
+			// Update vehicle position based on speed and heading
+			auto owner = device_id.unit;
+			if (!reg.all_of<OnGroundFlag>(owner)) {
+				// If not on ground, do not update position
+				return;
+			}
+
+			auto &kinematics = reg.get<KinematicsComponent>(owner);
+			kinematics.velocity += Vec2::rotated(
+				vehicle.heading, vehicle.speed * vehicle.prototype->max_speed
+			);
+		}
+		);
+	}
+
+	std::string_view name() const noexcept override {
+		return "Vehicle Device System";
+	}
+};
+
+static const VehicleVelocitySystem vehicle_velocity_system;
+static const SystemRegistry::Registar vehicle_velocity_registrar(
+	System::Precedence::DeviceAccumulateVelocity, &vehicle_velocity_system
+);
+
+} // namespace
+
+} // namespace istd

core/src/unit.cpp

@@ -0,0 +1,74 @@
+#include "istd_core/unit.h"
+#include "istd_core/system.h"
+#include "istd_util/tile_geometry.h"
+#include "tilemap/tile.h"
+
+namespace istd {
+
+namespace {
+
+struct ResetVelocitySystem : public System {
+	void tick(World &world) const noexcept override {
+		auto &reg = world.registry;
+		reg.view<KinematicsComponent>().each(
+			[](entt::entity, KinematicsComponent &kinematics) {
+			kinematics.velocity = Vec2::zero();
+		}
+		);
+	}
+
+	std::string_view name() const noexcept override {
+		return "Reset Velocity System";
+	}
+};
+
+static const ResetVelocitySystem reset_velocity_system;
+static const SystemRegistry::Registar reset_velocity_registrar(
+	System::Precedence::ResetVelocity, &reset_velocity_system
+);
+
+bool is_passible_tile(Tile tile) {
+	return tile.base != BaseTileType::Mountain;
+}
+
+void update_pos(const TileMap &tilemap, KinematicsComponent &kinematics) {
+	auto next_pos = kinematics.position + kinematics.velocity;
+	auto ray_cast = tiles_on_segment(kinematics.position, next_pos);
+	for (auto [i, j] : ray_cast) {
+		auto tile = tilemap.get_tile(TilePos::from_global(i, j));
+		if (!is_passible_tile(tile)) {
+			// Hit an impassable tile
+			// Calculate intersection point
+			auto inter = tile_segment_intersection(
+				kinematics.position, next_pos, {i, j}
+			);
+			next_pos = inter;
+			break;
+		}
+	}
+	kinematics.position = next_pos;
+}
+
+struct KinematicsSystem : public System {
+	void tick(World &world) const noexcept override {
+		auto &reg = world.registry;
+		reg.view<KinematicsComponent>().each(
+			std::bind(
+				update_pos, std::ref(world.tilemap), std::placeholders::_1
+			)
+		);
+	}
+
+	std::string_view name() const noexcept override {
+		return "Kinematics System";
+	}
+};
+
+static const KinematicsSystem kinematics_system;
+static const SystemRegistry::Registar kinematics_registrar(
+	System::Precedence::UpdateKinematics, &kinematics_system
+);
+
+} // namespace
+
+} // namespace istd