cgo

package main

import "C"

import (
    "fmt"
    "log"

    "github.com/peterstace/simplefeatures/geom"
    "github.com/twpayne/go-geos"
)

//export Add
func Add(a, b int) int {
    return a + b
}

//export GeomZDiff
func GeomZDiff(geomWkt *C.char) C.float {
    goGeomWkt := C.GoString(geomWkt)
    if goGeomWkt == "" {
        fmt.Println("geomWkt 为空")
        return C.float(0)
    }
    // 使用 WKT 解析器解析 WKT 字符串
    geom, err := geos.NewGeomFromWKT(goGeomWkt)
    if err != nil {
        fmt.Println("Error reading WKT:", err)
        return C.float(0)
    }

    if geom.TypeID() != geos.TypeIDLineString {
        fmt.Println("Geometry is not a LineString")
        return C.float(0)
    }
    if !geom.IsValid() {
        return C.float(0)
    }
    // 获取 LineString 的坐标
    coordSeq := geom.CoordSeq()
    coords := coordSeq.ToCoords()

    maxZ := coords[0][2]
    minZ := coords[0][2]
    for i := 1; i < len(coords); i++ {
        if coords[i][2] > maxZ {
            maxZ = coords[i][2]
        }
        if coords[i][2] < minZ {
            maxZ = coords[i][2]
        }
    }
    return C.float(maxZ - minZ)
}

//export GeomZDiff2
func GeomZDiff2(geomWkt *C.char) C.float {
    goGeomWkt := C.GoString(geomWkt)
    if goGeomWkt == "" {
        fmt.Println("geomWkt 为空")
        return C.float(0)
    }

    geom, err := geom.UnmarshalWKT(goGeomWkt)
    if err != nil {
        log.Fatalf("Failed to unmarshal WKT: %v", err)
        return C.float(0)
    }
    lineString, ok := geom.AsLineString()
    if !ok {
        return C.float(0)
    }
    err = lineString.Validate()
    if err != nil {
        return C.float(0)
    }
    coords := lineString.Coordinates()
    maxZ := coords.Get(0).Z
    minZ := coords.Get(0).Z
    for i := 1; i < coords.Length(); i++ {
        c := coords.Get(i)
        if c.Z > maxZ {
            maxZ = c.Z
        }
        if c.Z < minZ {
            maxZ = c.Z
        }
    }

    return C.float(maxZ - minZ)
}

func main() {
    // wkt := "LINESTRING Z(116.21126367 39.86818626 0.0000011, 116.21167992 39.86805255 0.00005, 116.21143061 39.86831677 0.00005, 116.21125012 39.86857083 0.00005)"
    // // wkt2 := "MULTILINESTRING ((0 0, 1 1), (0 0, 1 1))"
    // fmt.Println(GeomZDiff2(wkt))
}

// go build -o mylib.so -buildmode=c-shared mylib.go

import cffi

# 初始化 CFFI
ffi = cffi.FFI()

# 定义函数原型
ffi.cdef("""
    float GeomZDiff2(const char* geomWkt);
    float GeomZDiff(const char* geomWkt);
""")


# 加载共享库
C = ffi.dlopen("./mylib.so")


# 示例调用
# geom_wkt = "LINESTRING Z (30 10 5, 10 30 15, 40 40 10)"
geom_wkt = ""
z_diff = C.GeomZDiff2(geom_wkt.encode('utf-8'))
print("Z Difference:", z_diff)

z_diff = C.GeomZDiff(geom_wkt.encode('utf-8'))
print("Z Difference:", z_diff)