Question

编译代码时出现链接错误，我收到Xcode的警告：

变量'quickhull :: QuickHull :: Epsilon'的实例化这里需要，但没有可用的定义

这是函数的定义：

namespace quickhull {

    template<>
    const float QuickHull<float>::Epsilon = 0.0001f;

    template<>
    const double QuickHull<double>::Epsilon = 0.0000001;

    /*
     * Implementation of the algorithm
     */

    template<typename T>
    ConvexHull<T> QuickHull<T>::getConvexHull(const std::vector<Vector3<T>>& pointCloud, bool CCW, bool useOriginalIndices, T epsilon) {
        VertexDataSource<T> vertexDataSource(pointCloud);
        return getConvexHull(vertexDataSource,CCW,useOriginalIndices,epsilon);
    }




ConvexHull<FloatType> getConvexHull(const std::vector<Vector3<FloatType>>& pointCloud, bool CCW, bool useOriginalIndices, FloatType eps = Epsilon);




template<typename FloatType>
    class QuickHull {
        using vec3 = Vector3<FloatType>;

        static const FloatType Epsilon;

        ConvexHull<FloatType> getConvexHull(const VertexDataSource<FloatType>& pointCloud, bool CCW, bool useOriginalIndices, FloatType eps);
    public:
        // Computes convex hull for a given point cloud.
        // Params:
        //   pointCloud: a vector of of 3D points
        //   CCW: whether the output mesh triangles should have CCW orientation
        //   useOriginalIndices: should the output mesh use same vertex indices as the original point cloud. If this is false,
        //      then we generate a new vertex buffer which contains only the vertices that are part of the convex hull.
        //   eps: minimum distance to a plane to consider a point being on positive of it (for a point cloud with scale 1)
        ConvexHull<FloatType> getConvexHull(const std::vector<Vector3<FloatType>>& pointCloud, bool CCW, bool useOriginalIndices, FloatType eps = Epsilon);

}

电话

 QuickHull<float> qh; // Could be double as well


  hull = qh.getConvexHull(pointCloud, true, false);

链接错误

  "quickhull::QuickHull<float>::Epsilon", referenced from:
   "quickhull::QuickHull<float>::getConvexHull(std::__1::vector<quickhull::Vector3<float>, std::__1::allocator<quickhull::Vector3<float> > > const&, bool, bool, float)", referenced from:

Answer 1

通常，在类中声明静态数据成员时，必须提供变量定义＆＃34; outside＆＃34;类定义，例如

class Test {
   public:
   static int g;
};
...
int Test::g = 0;

同样的事情发生在＆＃34;生成＆＃34;通过模板，符号如下：

template<typename FloatType>
class QuickHull {
    static const FloatType Epsilon;
}
...
template<typename FloatType >
QuickHull<FloatType>::Epsilon = 0.0;

变量的实例化但没有定义可用

1 个答案: