feat: add tile geometry utilities and enhance Vec2 class with additional methods

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

util/CMakeLists.txt

@@ -4,6 +4,7 @@ cmake_minimum_required(VERSION 3.27)
 # Define util library sources
 add_library(istd_util STATIC
 	src/vec2.cpp
+	src/tile_geometry.cpp
 )
 target_include_directories(istd_util PUBLIC include)
 target_compile_features(istd_util PUBLIC cxx_std_23)

util/include/istd_util/tile_geometry.h

@@ -0,0 +1,33 @@
+#ifndef ISTD_UTIL_TILE_GEOMETRY_H
+#define ISTD_UTIL_TILE_GEOMETRY_H
+
+#include "istd_util/vec2.h"
+#include <cstdint>
+#include <generator>
+#include <tuple>
+
+namespace istd {
+
+/**
+ * @brief Iterates all tile coordinates traversed by a line segment on a
+ * tilemap.
+ *
+ * Uses the Amanatides-Woo algorithm to efficiently enumerate all integer tile
+ * positions that a segment from p1 to p2 passes through, including both
+ * endpoints.
+ *
+ * @note x points downward, y points rightward,
+ * i.e. x is row index, y is column index.
+ *
+ * @param p1 The starting point of the segment (floating point coordinates).
+ * @param p2 The ending point of the segment (floating point coordinates).
+ * @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(
+	Vec2 p1, Vec2 p2
+) noexcept;
+
+} // namespace istd
+
+#endif

util/include/istd_util/vec2.h

@@ -28,10 +28,12 @@ struct Vec2 {
 	 * @param y Y component
 	 */
 	Vec2(float x, float y) noexcept;
+
 	/**
 	 * @brief Returns a zero vector (0, 0).
 	 */
 	static Vec2 zero() noexcept;
+
 	/**
 	 * @brief Returns a vector rotated by the given angle.
 	 * @param rad Angle in radians
@@ -40,9 +42,15 @@ struct Vec2 {
 	static Vec2 rotated(float rad, float len = 1.0) noexcept;
 
 	/**
-	 * @name Symmetric operations
+	 * @brief Returns a vector with infinite components.
-	 * @{
 	 */
+	static Vec2 inf() noexcept;
+
+	/**
+	 * @brief Returns a vector with NaN components.
+	 */
+	static Vec2 invalid() noexcept;
+
 	/**
 	 * @brief Vector addition.
 	 */
@@ -67,12 +75,7 @@ struct Vec2 {
 	 * @brief Three-way comparison operator.
 	 */
 	friend std::strong_ordering operator<=>(Vec2 a, Vec2 b) noexcept;
-	/** @} */
 
-	/**
-	 * @name Assignment operations
-	 * @{
-	 */
 	/**
 	 * @brief Adds another vector to this vector.
 	 */
@@ -89,7 +92,6 @@ struct Vec2 {
 	 * @brief Divides this vector by a scalar.
 	 */
 	Vec2 &operator/=(float k) noexcept;
-	/** @} */
 
 	/**
 	 * @brief Access vector components by index.
@@ -123,22 +125,31 @@ struct Vec2 {
 		throw std::out_of_range("Index out of range for Vec2");
 	}
 
+	/**
+	 * @brief Checks if the vector is valid (not NaN).
+	 */
+	bool is_valid(this const Vec2 self) noexcept;
+
 	/**
 	 * @brief Returns the length (magnitude) of the vector.
 	 */
 	float length(this const Vec2 self) noexcept;
+
 	/**
 	 * @brief Returns the squared length of the vector.
 	 */
 	float length_squared(this const Vec2 self) noexcept;
+
 	/**
 	 * @brief Returns a normalized (unit length) vector.
 	 */
 	Vec2 normalized(this const Vec2 self) noexcept;
+
 	/**
 	 * @brief Returns a tuple of floored components.
 	 */
 	std::tuple<int, int> floor(this const Vec2 self) noexcept;
+
 	/**
 	 * @brief Returns a tuple of rounded components.
 	 */
@@ -147,11 +158,12 @@ struct Vec2 {
 	/**
 	 * @brief Returns the dot product of two vectors.
 	 */
-	friend float dot(Vec2 a, Vec2 b) noexcept;
+	static float dot(Vec2 a, Vec2 b) noexcept;
+
 	/**
 	 * @brief Returns the cross product of two vectors.
 	 */
-	friend float cross(Vec2 a, Vec2 b) noexcept;
+	static float cross(Vec2 a, Vec2 b) noexcept;
 };
 
 } // namespace istd

util/include/util.h

@@ -1 +1,3 @@
 #include "istd_util/small_map.h"
+#include "istd_util/tile_geometry.h"
+#include "istd_util/vec2.h"

util/src/tile_geometry.cpp

@@ -0,0 +1,52 @@
+#include "istd_util/tile_geometry.h"
+
+namespace istd {
+
+// Amanatides-Woo Algorithm
+std::generator<std::tuple<std::int32_t, std::int32_t>> tiles_on_segment(
+	Vec2 p1, Vec2 p2
+) noexcept {
+	auto [i, j] = p1.floor();
+	co_yield {i, j};
+	if (p1.floor() == p2.floor()) {
+		co_return;
+	}
+
+	auto delta = p2 - p1;
+	int step_x = 0, step_y = 0;
+	auto t_max = Vec2::inf(), t_delta = Vec2::inf();
+
+	if (delta.x > 0) {
+		step_x = 1;
+		t_max.x = (i + 1 - p1.x) / delta.x;
+		t_delta.x = 1.0f / delta.x;
+	} else if (delta.x < 0) {
+		step_x = -1;
+		t_max.x = (i - p1.x) / delta.x;
+		t_delta.x = -1.0f / delta.x;
+	}
+
+	if (delta.y > 0) {
+		step_y = 1;
+		t_max.y = (j + 1 - p1.y) / delta.y;
+		t_delta.y = 1.0f / delta.y;
+	} else if (delta.y < 0) {
+		step_y = -1;
+		t_max.y = (j - p1.y) / delta.y;
+		t_delta.y = -1.0f / delta.y;
+	}
+
+	auto [end_i, end_j] = p2.floor();
+	while (i != end_i || j != end_j) {
+		if (t_max.x < t_max.y) {
+			i += step_x;
+			t_max.x += t_delta.x;
+		} else {
+			j += step_y;
+			t_max.y += t_delta.y;
+		}
+		co_yield {i, j};
+	}
+}
+
+} // namespace istd

util/src/vec2.cpp

@@ -7,11 +7,25 @@ namespace istd {
 Vec2::Vec2(float x_, float y_) noexcept: x(x_), y(y_) {}
 
 Vec2 Vec2::zero() noexcept {
-	return Vec2(0.0f, 0.0f);
+	return {0.0f, 0.0f};
 }
 
 Vec2 Vec2::rotated(float rad, float len) noexcept {
-	return Vec2(std::cos(rad) * len, std::sin(rad) * len);
+	return {std::cos(rad) * len, std::sin(rad) * len};
+}
+
+Vec2 Vec2::inf() noexcept {
+	return Vec2(
+		std::numeric_limits<float>::infinity(),
+		std::numeric_limits<float>::infinity()
+	);
+}
+
+Vec2 Vec2::invalid() noexcept {
+	return Vec2(
+		std::numeric_limits<float>::quiet_NaN(),
+		std::numeric_limits<float>::quiet_NaN()
+	);
 }
 
 Vec2 operator+(Vec2 a, Vec2 b) noexcept {
@@ -74,6 +88,10 @@ Vec2 &Vec2::operator/=(float k) noexcept {
 	return *this;
 }
 
+bool Vec2::is_valid(this const Vec2 self) noexcept {
+	return !std::isnan(self.x) && !std::isnan(self.y);
+}
+
 float Vec2::length(this const Vec2 self) noexcept {
 	return std::sqrt(self.x * self.x + self.y * self.y);
 }
@@ -104,11 +122,11 @@ std::tuple<int, int> Vec2::round(this const Vec2 self) noexcept {
 	);
 }
 
-float dot(Vec2 a, Vec2 b) noexcept {
+float Vec2::dot(Vec2 a, Vec2 b) noexcept {
 	return a.x * b.x + a.y * b.y;
 }
 
-float cross(Vec2 a, Vec2 b) noexcept {
+float Vec2::cross(Vec2 a, Vec2 b) noexcept {
 	return a.x * b.y - a.y * b.x;
 }
 

util/test/CMakeLists.txt

@@ -1,16 +1,15 @@
 cmake_minimum_required(VERSION 3.27)
 
-
-add_executable(test_small_map small_map.cpp)
-target_link_libraries(test_small_map PRIVATE istd_util)
-target_compile_features(test_small_map PRIVATE cxx_std_23)
-
-add_executable(test_vec2 test_vec2.cpp)
-target_link_libraries(test_vec2 PRIVATE istd_util)
-target_compile_features(test_vec2 PRIVATE cxx_std_23)
-
-
 include(CTest)
 enable_testing()
-add_test(NAME util_small_map COMMAND test_small_map)
+
-add_test(NAME util_vec2 COMMAND test_vec2)
+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()
+
+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)

util/test/test_tile_geometry.cpp

@@ -0,0 +1,60 @@
+#include "istd_util/tile_geometry.h"
+#include <cassert>
+#include <tuple>
+#include <vector>
+using namespace istd;
+
+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);
+	}
+	// 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);
+	}
+	// 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);
+	}
+	// 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);
+	}
+	assert(result.size() == 1);
+	assert(result[0] == std::make_tuple(7, 8));
+
+	return 0;
+}

util/test/test_vec2.cpp

@@ -20,15 +20,25 @@ int main() {
 	Vec2 v4 = v1 - v2;
 	assert(v4.x == 2.0f && v4.y == 2.0f);
 
-	// Test dot and cross
-	assert(dot(v1, v2) == 11.0f);
-	assert(cross(v1, v2) == 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;
 }