cursor给的源码
函数声明
#include <geos/geom.h>
#include <geos.h>
// #include <geos_c.h>
#include<iostream>
#include <vector>
#include <memory>
using namespace geos::geom;
// 定义二维点类型（使用 double 坐标）
struct Pointd {
double x, y;
Pointd(double x = 0.0, double y = 0.0) : x(x), y(y) {}
};
// 函数声明：计算两个多边形集合的并集
int polygon_union(
const std::vector<std::vector<Pointd>>& polygons1,
const std::vector<std::vector<Pointd>>& polygons2,
std::vector<std::vector<Pointd>>& polygons_out,
bool& is_union);
函数实现
#include "Union.h"
#include <geos_c.h>
#include <vector>
#include <memory>
#include <iostream> // 用于调试
// 前向声明
static GEOSGeometry* createPolygonWithHoles(
GEOSContextHandle_t handle,
const std::vector<Pointd>& shell,
const std::vector<std::vector<Pointd>>& holes);
static void extractPolygon(
GEOSContextHandle_t handle,
const GEOSGeometry* poly,
std::vector<std::vector<Pointd>>& polygons_out);
int polygon_union(
const std::vector<std::vector<Pointd>>& polygons1,
const std::vector<std::vector<Pointd>>& polygons2,
std::vector<std::vector<Pointd>>& polygons_out,
bool& is_union) {
// 调试信息
std::cout << "Input polygons1 count: " << polygons1.size() << std::endl;
std::cout << "Input polygons2 count: " << polygons2.size() << std::endl;
// 初始化 GEOS
GEOSContextHandle_t handle = GEOS_init_r();
if (!handle) return -1;
try {
// 创建第一个多边形（带内环）
GEOSGeometry* poly1 = nullptr;
if (!polygons1.empty()) {
// 第一个vector是外环，其余的都是内环
const auto& shell = polygons1[0];
std::vector<std::vector<Pointd>> holes;
if (polygons1.size() > 1) {
holes.assign(polygons1.begin() + 1, polygons1.end());
}
poly1 = createPolygonWithHoles(handle, shell, holes);
}
// 创建第二个多边形（带内环）
GEOSGeometry* poly2 = nullptr;
if (!polygons2.empty()) {
const auto& shell = polygons2[0];
std::vector<std::vector<Pointd>> holes;
if (polygons2.size() > 1) {
holes.assign(polygons2.begin() + 1, polygons2.end());
}
poly2 = createPolygonWithHoles(handle, shell, holes);
}
// 检查输入是否有效
if (!poly1 && !poly2) {
is_union = false;
GEOS_finish_r(handle);
return -1;
}
// 计算并集
GEOSGeometry* result = nullptr;
if (!poly1) {
result = GEOSGeom_clone_r(handle, poly2);
is_union = false;
}
else if (!poly2) {
result = GEOSGeom_clone_r(handle, poly1);
is_union = false;
}
else {
result = GEOSUnion_r(handle, poly1, poly2);
// 检查是否有相交
GEOSGeometry* intersection = GEOSIntersection_r(handle, poly1, poly2);
is_union = intersection && !GEOSisEmpty_r(handle, intersection);
if (intersection) GEOSGeom_destroy_r(handle, intersection);
}
// 提取结果
polygons_out.clear();
if (result) {
int type = GEOSGeomTypeId_r(handle, result);
if (type == 3) { // GEOS_POLYGON
// 提取单个多边形
extractPolygon(handle, result, polygons_out);
}
else if (type == 6) { // GEOS_MULTIPOLYGON
// 处理多个多边形的情况
for (int i = 0; i < GEOSGetNumGeometries_r(handle, result); i++) {
const GEOSGeometry* geom = GEOSGetGeometryN_r(handle, result, i);
if (geom) {
size_t current_size = polygons_out.size();
extractPolygon(handle, geom, polygons_out);
// 如果这不是第一个多边形，在结果中添加分隔标记
if (i > 0 && polygons_out.size() > current_size) {
// 可以在这里添加多边形之间的分隔标记
// 比如添加一个空的vector作为分隔符
polygons_out.push_back(std::vector<Pointd>());
}
}
}
}
}
// 清理资源
if (poly1) GEOSGeom_destroy_r(handle, poly1);
if (poly2) GEOSGeom_destroy_r(handle, poly2);
if (result) GEOSGeom_destroy_r(handle, result);
GEOS_finish_r(handle);
return 0;
} catch (const std::exception& e) {
std::cout << "Exception: " << e.what() << std::endl;
if (handle) GEOS_finish_r(handle);
return -1;
} catch (...) {
std::cout << "Unknown exception occurred" << std::endl;
if (handle) GEOS_finish_r(handle);
return -1;
}
}
// 辅助函数：创建带内环的多边形
static GEOSGeometry* createPolygonWithHoles(
GEOSContextHandle_t handle,
const std::vector<Pointd>& shell,
const std::vector<std::vector<Pointd>>& holes) {
if (shell.size() < 3) return nullptr;
// 创建外环
GEOSCoordSequence* shell_seq = GEOSCoordSeq_create_r(handle, shell.size() + 1, 2);
for (size_t i = 0; i < shell.size(); i++) {
GEOSCoordSeq_setX_r(handle, shell_seq, i, shell[i].x);
GEOSCoordSeq_setY_r(handle, shell_seq, i, shell[i].y);
}
// 闭合多边形
GEOSCoordSeq_setX_r(handle, shell_seq, shell.size(), shell[0].x);
GEOSCoordSeq_setY_r(handle, shell_seq, shell.size(), shell[0].y);
GEOSGeometry* shell_ring = GEOSGeom_createLinearRing_r(handle, shell_seq);
if (!shell_ring) return nullptr;
// 创建内环
std::vector<GEOSGeometry*> hole_rings;
for (const auto& hole : holes) {
if (hole.size() < 3) continue;
GEOSCoordSequence* hole_seq = GEOSCoordSeq_create_r(handle, hole.size() + 1, 2);
for (size_t i = 0; i < hole.size(); i++) {
GEOSCoordSeq_setX_r(handle, hole_seq, i, hole[i].x);
GEOSCoordSeq_setY_r(handle, hole_seq, i, hole[i].y);
}
// 闭合内环
GEOSCoordSeq_setX_r(handle, hole_seq, hole.size(), hole[0].x);
GEOSCoordSeq_setY_r(handle, hole_seq, hole.size(), hole[0].y);
GEOSGeometry* hole_ring = GEOSGeom_createLinearRing_r(handle, hole_seq);
if (hole_ring) {
hole_rings.push_back(hole_ring);
}
}
// 创建完整的多边形
GEOSGeometry* polygon = GEOSGeom_createPolygon_r(
handle,
shell_ring,
hole_rings.data(),
hole_rings.size()
);
return polygon;
}
// 辅助函数：提取多边形的坐标
static void extractPolygon(
GEOSContextHandle_t handle,
const GEOSGeometry* poly,
std::vector<std::vector<Pointd>>& polygons_out) {
// 提取外环
const GEOSGeometry* shell = GEOSGetExteriorRing_r(handle, poly);
if (shell) {
std::vector<Pointd> shell_points;
const GEOSCoordSequence* coords = GEOSGeom_getCoordSeq_r(handle, shell);
unsigned int size;
GEOSCoordSeq_getSize_r(handle, coords, &size);
for (unsigned int i = 0; i < size - 1; i++) { // size-1 to avoid duplicate point
double x, y;
GEOSCoordSeq_getX_r(handle, coords, i, &x);
GEOSCoordSeq_getY_r(handle, coords, i, &y);
shell_points.emplace_back(x, y);
}
if (!shell_points.empty()) {
polygons_out.push_back(shell_points);
}
// 提取内环
int num_holes = GEOSGetNumInteriorRings_r(handle, poly);
for (int i = 0; i < num_holes; i++) {
const GEOSGeometry* hole = GEOSGetInteriorRingN_r(handle, poly, i);
if (hole) {
std::vector<Pointd> hole_points;
coords = GEOSGeom_getCoordSeq_r(handle, hole);
GEOSCoordSeq_getSize_r(handle, coords, &size);
for (unsigned int j = 0; j < size - 1; j++) { // size-1 to avoid duplicate point
double x, y;
GEOSCoordSeq_getX_r(handle, coords, j, &x);
GEOSCoordSeq_getY_r(handle, coords, j, &y);
hole_points.emplace_back(x, y);
}
if (!hole_points.empty()) {
polygons_out.push_back(hole_points);
}
}
}
}
}
使用示例
#include <iostream>
#include <vector>
#include "Union.h"
int main() {
// 第一个多边形：正方形 (0,0) -> (1,0) -> (1,1) -> (0,1)
std::vector<std::vector<Pointd>> polygons1 = {
{ // 外环
Pointd(0, 0),
Pointd(1, 0),
Pointd(1, 1),
Pointd(0, 1)
}
// 可以添加内环，如: {Pointd(...), Pointd(...), ...}
};
// 第二个多边形：正方形 (0.5,0.5) -> (1.5,0.5) -> (1.5,1.5) -> (0.5,1.5)
std::vector<std::vector<Pointd>> polygons2 = {
{ // 外环
Pointd(0.5, 0.5),
Pointd(1.5, 0.5),
Pointd(1.5, 1.5),
Pointd(0.5, 1.5)
}
};
std::vector<std::vector<Pointd>> result;
bool is_union;
int status = polygon_union(polygons1, polygons2, result, is_union);
if (status == 0) {
std::cout << "Union successful!" << std::endl;
std::cout << "Is union: " << (is_union ? "true" : "false") << std::endl;
std::cout << "Result has " << result.size() << " rings:" << std::endl;
for (size_t i = 0; i < result.size(); ++i) {
std::cout << (i == 0 ? "Exterior ring: " : "Interior ring: ");
for (const auto& p : result[i]) {
std::cout << "(" << p.x << "," << p.y << ") ";
}
std::cout << std::endl;
}
} else {
std::cerr << "Union failed!" << std::endl;
}
return 0;
}
cmake文件
cmake_minimum_required(VERSION 3.10)
project(MyProject)
# 使用 pkg-config 查找 GEOS
find_package(PkgConfig REQUIRED)
pkg_check_modules(GEOS REQUIRED geos)
# GEOS 3.13 源码默认安装路径
set(GEOS_INCLUDE_DIR "/usr/local/include/geos")
set(GEOS_LIBRARY_DIR "/usr/local/lib")
# 添加可执行文件
add_executable(my_app main.cpp Union.cpp)
target_include_directories(my_app PRIVATE ${GEOS_INCLUDE_DIR})
target_link_directories(my_app PRIVATE ${GEOS_LIBRARY_DIR})
target_link_libraries(my_app ${GEOS_LIBRARIES})
安装和准备
参考官方Download and Build
先下载源码包geos-3.13.1.tar.bz2
然后执行解压和编译，测试，安装
# Unpack and setup build directory
tar xvfj geos-3.13.1.tar.bz2
cd geos-3.13.1
mkdir _build
cd _build
# Set up the build
cmake \
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_INSTALL_PREFIX=/usr/local \
..
# Run the build, test, install
make
ctest
make install
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