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 {
-	static DeviceBuilderRegistry &instance();
+class DeviceBuilderRegistry {
+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

third_party/CMakeLists.txt

@@ -3,6 +3,7 @@ cmake_minimum_required(VERSION 3.27)
 set(ISTD_THIRD_PARTY_LIBS
     entt
     asio
+	catch2
 )
 
 foreach(lib IN LISTS ISTD_THIRD_PARTY_LIBS)

third_party/catch2.cmake

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.27)
+cmake_policy(VERSION 3.27)
+include(FetchContent)
+
+# Catch2 third-party library setup
+message(STATUS "Downloading Catch2...")
+FetchContent_Declare(
+	Catch2
+	URL "https://github.com/catchorg/Catch2/archive/refs/tags/v3.9.0.zip"
+)
+FetchContent_MakeAvailable(Catch2)
+message(STATUS "Catch2 ready")

util/include/istd_util/tile_geometry.h

@@ -2,9 +2,9 @@
 #define ISTD_UTIL_TILE_GEOMETRY_H
 
 #include "istd_util/vec2.h"
+#include <array>
 #include <cstdint>
 #include <generator>
-#include <tuple>
 
 namespace istd {
 
@@ -24,10 +24,30 @@ namespace istd {
  * @return Generator yielding (i, j) tuples for each tile crossed by the
  * segment.
  */
-std::generator<std::tuple<std::int32_t, std::int32_t>> tiles_on_segment(
+std::generator<std::array<std::int32_t, 2>> tiles_on_segment(
 	Vec2 p1, Vec2 p2
 ) noexcept;
 
+/**
+ * @brief Computes the first intersection point between a line segment and a
+ * tile in the tilemap.
+ *
+ * Uses a coordinate system where x points downward (row index) and y points
+ * rightward (column index). Finds the intersection point (closest to p1)
+ * between the segment from p1 to p2 and the square tile specified by (i, j),
+ * where the tile is defined as the region from (i, j) to (i+1, j+1).
+ *
+ * @param p1 The starting point of the segment (floating point coordinates).
+ * @param p2 The ending point of the segment (floating point coordinates).
+ * @param tile The tile indices (i, j) representing the square from (i, j) to
+ * (i+1, j+1).
+ * @return The intersection point as a Vec2, or an undefined value if there is
+ * no intersection.
+ */
+Vec2 tile_segment_intersection(
+	Vec2 p1, Vec2 p2, std::array<std::int32_t, 2> tile
+) noexcept;
+
 } // namespace istd
 
 #endif

util/src/tile_geometry.cpp

@@ -3,7 +3,7 @@
 namespace istd {
 
 // Amanatides-Woo Algorithm
-std::generator<std::tuple<std::int32_t, std::int32_t>> tiles_on_segment(
+std::generator<std::array<std::int32_t, 2>> tiles_on_segment(
 	Vec2 p1, Vec2 p2
 ) noexcept {
 	auto [i, j] = p1.floor();
@@ -38,7 +38,13 @@ std::generator<std::tuple<std::int32_t, std::int32_t>> tiles_on_segment(
 
 	auto [end_i, end_j] = p2.floor();
 	while (i != end_i || j != end_j) {
-		if (t_max.x < t_max.y) {
+		if (std::abs(t_max.x - t_max.y) < 1e-6f) {
+			// Both directions are equal, choose one arbitrarily
+			i += step_x;
+			j += step_y;
+			t_max.x += t_delta.x;
+			t_max.y += t_delta.y;
+		} else if (t_max.x < t_max.y) {
 			i += step_x;
 			t_max.x += t_delta.x;
 		} else {
@@ -49,4 +55,48 @@ std::generator<std::tuple<std::int32_t, std::int32_t>> tiles_on_segment(
 	}
 }
 
+Vec2 tile_segment_intersection(
+	Vec2 p1, Vec2 p2, std::array<std::int32_t, 2> tile
+) noexcept {
+	// Tile bounds: [i, i+1) x [j, j+1)
+	float i = static_cast<float>(tile[0]);
+	float j = static_cast<float>(tile[1]);
+	float min_x = i, max_x = i + 1;
+	float min_y = j, max_y = j + 1;
+
+	// Parametric line: p = p1 + t * (p2 - p1), t in [0, 1]
+	Vec2 d = p2 - p1;
+	float t_min = 0.0f, t_max = 1.0f;
+
+	// For each slab (x and y), compute intersection interval
+	for (int axis = 0; axis < 2; ++axis) {
+		float p = axis == 0 ? p1.x : p1.y;
+		float q = axis == 0 ? d.x : d.y;
+		float slab_min = axis == 0 ? min_x : min_y;
+		float slab_max = axis == 0 ? max_x : max_y;
+		if (std::abs(q) < 1e-8f) {
+			// Parallel to slab, outside
+			if (p < slab_min || p > slab_max) {
+				return Vec2::invalid();
+			}
+		} else {
+			float t1 = (slab_min - p) / q;
+			float t2 = (slab_max - p) / q;
+			if (t1 > t2) {
+				std::swap(t1, t2);
+			}
+			t_min = std::max(t_min, t1);
+			t_max = std::min(t_max, t2);
+			if (t_min > t_max) {
+				return Vec2::invalid();
+			}
+		}
+	}
+	// Intersection exists in [t_min, t_max], want closest to p1 (t_min >= 0)
+	if (t_min < 0.0f || t_min > 1.0f) {
+		return Vec2::invalid();
+	}
+	return p1 + d * t_min;
+}
+
 } // namespace istd

util/test/CMakeLists.txt

@@ -3,13 +3,15 @@ cmake_minimum_required(VERSION 3.27)
 include(CTest)
 enable_testing()
 
-function(declare_istd_util_test name src)
-    add_executable(${name} ${src})
-    target_link_libraries(${name} PRIVATE istd_util)
-    target_compile_features(${name} PRIVATE cxx_std_23)
-    add_test(NAME ${name} COMMAND ${name})
-endfunction()
+# Create a unified test executable from multiple source files
+add_executable(istd_util_tests 
+    test_small_map.cpp
+    test_vec2.cpp 
+    test_tile_geometry.cpp
+)
 
-declare_istd_util_test(test_small_map small_map.cpp)
-declare_istd_util_test(test_vec2 test_vec2.cpp)
-declare_istd_util_test(test_tile_geometry test_tile_geometry.cpp)
+target_link_libraries(istd_util_tests PRIVATE istd_util Catch2::Catch2WithMain)
+target_compile_features(istd_util_tests PRIVATE cxx_std_23)
+
+# Add the test to CTest
+add_test(NAME istd_util_tests COMMAND istd_util_tests)

util/test/small_map.cpp

@@ -1,77 +0,0 @@
-#include "istd_util/small_map.h"
-#include <cassert>
-
-int main() {
-	using namespace istd;
-	// Test insert and size
-	SmallMap<int, int> map;
-	assert(map.empty());
-	map.insert(1, 10);
-	map.insert(2, 20);
-	map.insert(3, 30);
-	assert(map.size() == 3);
-	assert(!map.empty());
-
-	// Test operator[]
-	assert(map[1] == 10);
-	assert(map[2] == 20);
-	assert(map[3] == 30);
-
-	// Test erase
-	map.erase(2);
-	assert(map.size() == 2);
-	assert(map[1] == 10);
-	assert(map[3] == 30);
-
-	// Test clear
-	map.clear();
-	assert(map.empty());
-
-	// Test duplicate insert throws
-	SmallMap<int, int> map2;
-	map2.insert(5, 50);
-	bool thrown = false;
-	try {
-		map2.insert(5, 60);
-	} catch (const std::invalid_argument &) {
-		thrown = true;
-	}
-	assert(thrown);
-
-	// Test out_of_range on operator[]
-	thrown = false;
-	try {
-		(void)map2[99];
-	} catch (const std::out_of_range &) {
-		thrown = true;
-	}
-	assert(thrown);
-
-	// Test erase throws on missing key
-	thrown = false;
-	try {
-		map2.erase(99);
-	} catch (const std::out_of_range &) {
-		thrown = true;
-	}
-	assert(thrown);
-
-	// Test iterator
-	map2.insert(6, 60);
-	map2.insert(7, 70);
-	int sum = 0;
-	for (auto it = map2.begin(); it != map2.end(); ++it) {
-		sum += it->value;
-	}
-	assert(sum == 180); // 50 + 60 + 70
-
-	// Test const iterators
-	const auto &cmap = map2;
-	sum = 0;
-	for (auto it = cmap.cbegin(); it != cmap.cend(); ++it) {
-		sum += it->value;
-	}
-	assert(sum == 180);
-
-	return 0;
-}

util/test/test_small_map.cpp

@@ -0,0 +1,103 @@
+#include "istd_util/small_map.h"
+#include <catch2/catch_approx.hpp>
+#include <catch2/catch_test_macros.hpp>
+
+using namespace istd;
+
+TEST_CASE("SmallMap basic operations", "[small_map]") {
+	SECTION("insert and size") {
+		SmallMap<int, int> map;
+		REQUIRE(map.empty());
+
+		map.insert(1, 10);
+		map.insert(2, 20);
+		map.insert(3, 30);
+
+		REQUIRE(map.size() == 3);
+		REQUIRE_FALSE(map.empty());
+	}
+
+	SECTION("operator[] access") {
+		SmallMap<int, int> map;
+		map.insert(1, 10);
+		map.insert(2, 20);
+		map.insert(3, 30);
+
+		REQUIRE(map[1] == 10);
+		REQUIRE(map[2] == 20);
+		REQUIRE(map[3] == 30);
+	}
+
+	SECTION("erase operation") {
+		SmallMap<int, int> map;
+		map.insert(1, 10);
+		map.insert(2, 20);
+		map.insert(3, 30);
+
+		map.erase(2);
+		REQUIRE(map.size() == 2);
+		REQUIRE(map[1] == 10);
+		REQUIRE(map[3] == 30);
+	}
+
+	SECTION("clear operation") {
+		SmallMap<int, int> map;
+		map.insert(1, 10);
+		map.insert(2, 20);
+
+		map.clear();
+		REQUIRE(map.empty());
+	}
+}
+
+TEST_CASE("SmallMap exception handling", "[small_map]") {
+	SECTION("duplicate insert throws") {
+		SmallMap<int, int> map;
+		map.insert(5, 50);
+
+		REQUIRE_THROWS_AS(map.insert(5, 60), std::invalid_argument);
+	}
+
+	SECTION("out_of_range on operator[]") {
+		SmallMap<int, int> map;
+		map.insert(5, 50);
+
+		REQUIRE_THROWS_AS(map[99], std::out_of_range);
+	}
+
+	SECTION("erase throws on missing key") {
+		SmallMap<int, int> map;
+		map.insert(5, 50);
+
+		REQUIRE_THROWS_AS(map.erase(99), std::out_of_range);
+	}
+}
+
+TEST_CASE("SmallMap iterators", "[small_map]") {
+	SECTION("iterator traversal") {
+		SmallMap<int, int> map;
+		map.insert(5, 50);
+		map.insert(6, 60);
+		map.insert(7, 70);
+
+		int sum = 0;
+		for (auto it = map.begin(); it != map.end(); ++it) {
+			sum += it->value;
+		}
+		REQUIRE(sum == 180); // 50 + 60 + 70
+	}
+
+	SECTION("const iterators") {
+		SmallMap<int, int> map;
+		map.insert(5, 50);
+		map.insert(6, 60);
+		map.insert(7, 70);
+
+		const auto &cmap = map;
+		int sum = 0;
+		for (auto it = cmap.cbegin(); it != cmap.cend(); ++it) {
+			sum += it->value;
+		}
+		REQUIRE(sum == 180);
+	}
+}

util/test/test_tile_geometry.cpp

@@ -1,60 +1,112 @@
 #include "istd_util/tile_geometry.h"
-#include <cassert>
+#include <catch2/catch_approx.hpp>
+#include <catch2/catch_test_macros.hpp>
 #include <tuple>
 #include <vector>
+
 using namespace istd;
+using Catch::Approx;
 
-int main() {
-	// Test a simple horizontal segment
-	Vec2 p1(0.5f, 1.2f);
-	Vec2 p2(0.5f, 4.8f);
-	std::vector<std::tuple<int, int>> result;
-	for (auto [i, j] : tiles_on_segment(p1, p2)) {
-		result.emplace_back(i, j);
+TEST_CASE("tiles_on_segment function", "[tile_geometry]") {
+	SECTION("horizontal segment") {
+		Vec2 p1(0.5f, 1.2f);
+		Vec2 p2(0.5f, 4.8f);
+		std::vector<std::tuple<int, int>> result;
+		for (auto [i, j] : tiles_on_segment(p1, p2)) {
+			result.emplace_back(i, j);
+		}
+
+		// Should traverse columns 1 to 4, row 0
+		REQUIRE(result.size() == 4);
+		REQUIRE(result[0] == std::make_tuple(0, 1));
+		REQUIRE(result[1] == std::make_tuple(0, 2));
+		REQUIRE(result[2] == std::make_tuple(0, 3));
+		REQUIRE(result[3] == std::make_tuple(0, 4));
 	}
-	// Should traverse columns 1 to 4, row 0
-	assert(result.size() == 4);
-	assert(result[0] == std::make_tuple(0, 1));
-	assert(result[1] == std::make_tuple(0, 2));
-	assert(result[2] == std::make_tuple(0, 3));
-	assert(result[3] == std::make_tuple(0, 4));
 
-	// Test a diagonal segment
-	p1 = Vec2(1.1f, 1.1f);
-	p2 = Vec2(3.9f, 3.9f);
-	result.clear();
-	for (auto [i, j] : tiles_on_segment(p1, p2)) {
-		result.emplace_back(i, j);
+	SECTION("diagonal segment") {
+		Vec2 p1(1.1f, 1.1f);
+		Vec2 p2(3.9f, 3.9f);
+		std::vector<std::tuple<int, int>> result;
+		for (auto [i, j] : tiles_on_segment(p1, p2)) {
+			result.emplace_back(i, j);
+		}
+
+		// Should traverse (1,1), (2,2), (3,3)
+		REQUIRE(result.size() == 3);
+		REQUIRE(result[0] == std::make_tuple(1, 1));
+		REQUIRE(result[1] == std::make_tuple(2, 2));
+		REQUIRE(result[2] == std::make_tuple(3, 3));
 	}
-	// Should traverse (1,1), (2,2), (3,3)
-	assert(result.size() == 3);
-	assert(result[0] == std::make_tuple(1, 1));
-	assert(result[1] == std::make_tuple(2, 2));
-	assert(result[2] == std::make_tuple(3, 3));
 
-	// Test vertical segment
-	p1 = Vec2(2.2f, 0.5f);
-	p2 = Vec2(5.7f, 0.5f);
-	result.clear();
-	for (auto [i, j] : tiles_on_segment(p1, p2)) {
-		result.emplace_back(i, j);
+	SECTION("vertical segment") {
+		Vec2 p1(2.2f, 0.5f);
+		Vec2 p2(5.7f, 0.5f);
+		std::vector<std::tuple<int, int>> result;
+		for (auto [i, j] : tiles_on_segment(p1, p2)) {
+			result.emplace_back(i, j);
+		}
+
+		// Should traverse rows 2 to 5, column 0
+		REQUIRE(result.size() == 4);
+		REQUIRE(result[0] == std::make_tuple(2, 0));
+		REQUIRE(result[1] == std::make_tuple(3, 0));
+		REQUIRE(result[2] == std::make_tuple(4, 0));
+		REQUIRE(result[3] == std::make_tuple(5, 0));
 	}
-	// Should traverse rows 2 to 5, column 0
-	assert(result.size() == 4);
-	assert(result[0] == std::make_tuple(2, 0));
-	assert(result[1] == std::make_tuple(3, 0));
-	assert(result[2] == std::make_tuple(4, 0));
-	assert(result[3] == std::make_tuple(5, 0));
 
-	// Test single tile
-	p1 = Vec2(7.3f, 8.9f);
-	p2 = Vec2(7.7f, 8.1f);
-	result.clear();
-	for (auto [i, j] : tiles_on_segment(p1, p2)) {
-		result.emplace_back(i, j);
+	SECTION("single tile") {
+		Vec2 p1(7.3f, 8.9f);
+		Vec2 p2(7.7f, 8.1f);
+		std::vector<std::tuple<int, int>> result;
+		for (auto [i, j] : tiles_on_segment(p1, p2)) {
+			result.emplace_back(i, j);
+		}
+
+		REQUIRE(result.size() == 1);
+		REQUIRE(result[0] == std::make_tuple(7, 8));
+	}
+}
+
+TEST_CASE("tile_segment_intersection function", "[tile_geometry]") {
+	SECTION("horizontal segment intersection") {
+		Vec2 p1(0.5f, 1.2f);
+		Vec2 p2(0.5f, 4.8f);
+		Vec2 inter = tile_segment_intersection(p1, p2, {0, 2});
+
+		REQUIRE(inter.is_valid());
+		REQUIRE(inter.x == Approx(0.5f).epsilon(1e-6));
+		REQUIRE(inter.y >= 2.0f);
+		REQUIRE(inter.y <= 3.0f);
+	}
+
+	SECTION("diagonal segment intersection") {
+		Vec2 p1(1.1f, 1.1f);
+		Vec2 p2(3.9f, 3.9f);
+		Vec2 inter = tile_segment_intersection(p1, p2, {2, 2});
+
+		REQUIRE(inter.is_valid());
+		REQUIRE(inter.x >= 2.0f);
+		REQUIRE(inter.x <= 3.0f);
+		REQUIRE(inter.y >= 2.0f);
+		REQUIRE(inter.y <= 3.0f);
+	}
+
+	SECTION("no intersection") {
+		Vec2 p1(0.0f, 0.0f);
+		Vec2 p2(0.5f, 0.5f);
+		Vec2 inter = tile_segment_intersection(p1, p2, {2, 2});
+
+		REQUIRE_FALSE(inter.is_valid());
+	}
+
+	SECTION("segment starts inside tile") {
+		Vec2 p1(2.2f, 2.2f);
+		Vec2 p2(5.0f, 5.0f);
+		Vec2 inter = tile_segment_intersection(p1, p2, {2, 2});
+
+		REQUIRE(inter.is_valid());
+		REQUIRE(inter.x == Approx(2.2f).epsilon(1e-6));
+		REQUIRE(inter.y == Approx(2.2f).epsilon(1e-6));
 	}
-	assert(result.size() == 1);
-	assert(result[0] == std::make_tuple(7, 8));
-
-	return 0;
 }

util/test/test_vec2.cpp

@@ -1,44 +1,89 @@
 #include "istd_util/vec2.h"
-#include <cassert>
-using namespace istd;
+#include <catch2/catch_approx.hpp>
+#include <catch2/catch_test_macros.hpp>
+#include <cmath>
 
-int main() {
+using namespace istd;
+using Catch::Approx;
+
+TEST_CASE("Vec2 length operations", "[vec2]") {
+	Vec2 v1(3.0f, 4.0f);
+
+	SECTION("length calculation") {
+		REQUIRE(v1.length() == 5.0f);
+		REQUIRE(v1.length_squared() == 25.0f);
+	}
+
+	SECTION("normalized vector") {
+		Vec2 n = v1.normalized();
+		REQUIRE(n.length() == Approx(1.0f).epsilon(1e-6));
+	}
+}
+
+TEST_CASE("Vec2 arithmetic operations", "[vec2]") {
 	Vec2 v1(3.0f, 4.0f);
 	Vec2 v2(1.0f, 2.0f);
 
-	// Test length and length_squared
-	assert(v1.length() == 5.0f);
-	assert(v1.length_squared() == 25.0f);
+	SECTION("addition") {
+		Vec2 v3 = v1 + v2;
+		REQUIRE(v3.x == 4.0f);
+		REQUIRE(v3.y == 6.0f);
+	}
 
-	// Test normalized
-	Vec2 n = v1.normalized();
-	assert(std::abs(n.length() - 1.0f) < 1e-6);
-
-	// Test addition and subtraction
-	Vec2 v3 = v1 + v2;
-	assert(v3.x == 4.0f && v3.y == 6.0f);
-	Vec2 v4 = v1 - v2;
-	assert(v4.x == 2.0f && v4.y == 2.0f);
-
-	// Test floor and round
-	Vec2 v5(1.7f, -2.3f);
-	auto f = v5.floor();
-	auto r = v5.round();
-	assert(f == std::make_tuple(1, -3));
-	assert(r == std::make_tuple(2, -2));
-
-	// Test inf and invalid
-	Vec2 vinf = Vec2::inf();
-	assert(std::isinf(vinf.x) && std::isinf(vinf.y));
-	Vec2 vinvalid = Vec2::invalid();
-	assert(std::isnan(vinvalid.x) && std::isnan(vinvalid.y));
-
-	// Test is_valid
-	assert(v1.is_valid());
-	assert(!vinvalid.is_valid());
-
-	// Test static dot and cross
-	assert(Vec2::dot(v1, v2) == 11.0f);
-	assert(Vec2::cross(v1, v2) == 2.0f);
-	return 0;
+	SECTION("subtraction") {
+		Vec2 v4 = v1 - v2;
+		REQUIRE(v4.x == 2.0f);
+		REQUIRE(v4.y == 2.0f);
+	}
+}
+
+TEST_CASE("Vec2 rounding operations", "[vec2]") {
+	Vec2 v5(1.7f, -2.3f);
+
+	SECTION("floor operation") {
+		auto [i, j] = v5.floor();
+		REQUIRE(i == 1);
+		REQUIRE(j == -3);
+	}
+
+	SECTION("round operation") {
+		auto [i, j] = v5.round();
+		REQUIRE(i == 2);
+		REQUIRE(j == -2);
+	}
+}
+
+TEST_CASE("Vec2 special values", "[vec2]") {
+	SECTION("infinity vector") {
+		Vec2 vinf = Vec2::inf();
+		REQUIRE(std::isinf(vinf.x));
+		REQUIRE(std::isinf(vinf.y));
+	}
+
+	SECTION("invalid vector") {
+		Vec2 vinvalid = Vec2::invalid();
+		REQUIRE(std::isnan(vinvalid.x));
+		REQUIRE(std::isnan(vinvalid.y));
+	}
+
+	SECTION("validity check") {
+		Vec2 v1(3.0f, 4.0f);
+		Vec2 vinvalid = Vec2::invalid();
+
+		REQUIRE(v1.is_valid());
+		REQUIRE_FALSE(vinvalid.is_valid());
+	}
+}
+
+TEST_CASE("Vec2 static operations", "[vec2]") {
+	Vec2 v1(3.0f, 4.0f);
+	Vec2 v2(1.0f, 2.0f);
+
+	SECTION("dot product") {
+		REQUIRE(Vec2::dot(v1, v2) == 11.0f);
+	}
+
+	SECTION("cross product") {
+		REQUIRE(Vec2::cross(v1, v2) == 2.0f);
+	}
 }