Question

所以我有这样的代码：

#include <iostream>
#include <string>
using namespace std;

#pragma region Class Definitions

struct Vector3
{
    double x;
    double y;
    double z;
};

class Plane {
    Vector3 point, normal, p_p1, p_p2, p_p3;
public:
    Plane(Vector3 p1,
        Vector3 p2, Vector3 p3);
    const Vector3& get_point() const;
    const Vector3& get_normal() const;
    double get_hnf_d() const;
    Vector3 closest_point(const Vector3& p);
    double distance_to(const Vector3& p);
    Vector3 intersect_line(const Line &l);


};    

int main()
{   
    a.x = 1;
    a.y = 2;
    a.z = 3;

    b.x = -1;
    b.y = 2;
    b.z = -2;

    s = -2;

    o.x = 0;
    o.y = 0;
    o.z = 0;

    p1.x = sqrt(1 / 8);
    p1.y = sqrt(1 / 8);
    p1.z = sqrt(3 / 4);

    p2.x = 0;
    p2.y = 2 * sqrt(1 / 8);
    p2.z = 0;

    p3.x = sqrt(1 / 8) + sqrt(3 / 8);
    p3.y = sqrt(1 / 8) + sqrt(3 / 8);
    p3.z = sqrt(3 / 4) - sqrt(1 / 4);

    q1.x = 1;
    q1.y = 1;
    q1.z = 1;

    q2.x = -1;
    q2.y = -1;
    q2.z = -1;  

    switch (choice)
    {    

 ...
            Plane _plane(p1, p2, p3);
            cout << "Distance to p1, p2, p3 respectievly is : " << _plane.distance_to(p1) << endl;

    }
    return 0;
}

Plane::Plane(Vector3 p1, Vector3 p2, Vector3 p3)
{
    p_p1 = p1;
    p_p2 = p2;
    p_p3 = p3;
}

const Vector3 & Plane::get_point() const
{
    return p_p1;
}

const Vector3 & Plane::get_normal() const
{
    return normalize(p_p2);
}

double Plane::get_hnf_d() const
{
    Vector3 n, numerator;
    double denominator;
    numerator = cross_product(substract(p_p1, p_p3), substract(p_p2, p_p3));
    denominator = sqrt(pow(numerator.x, 2) + pow(numerator.y, 2) + pow(numerator.z, 2));
    cout <<"read" << numerator.y << numerator.x << denominator;
    n.x = numerator.x / denominator;
    n.y = numerator.y / denominator;
    n.z = numerator.z / denominator;
    //distance from origin
    return -1 * dot_product(p_p1, n);
}

Vector3 Plane::closest_point(const Vector3 & p)
{
    return Vector3();
}

double Plane::distance_to(const Vector3 & p)
{

    return get_hnf_d() + dot_product(p, get_normal()) ;
}

我正在设置这样的值：

Plane::Plane(Vector3 p1, Vector3 p2, Vector3 p3)
{
    p_p1 = p1;
    p_p2 = p2;
    p_p3 = p3;
}

然而，每当我尝试说print p_p1.x时，我总是会返回值为0，从而导致我的计算失败。我哪里错了？我真的是一名C ++初学者。

感谢。

Answer 1

你在行中进行整数除法：

p1.x = sqrt(1 / 8);

1/8在C ++中为0

在所有其他初始化中都是如此。

尝试写作

p1.x = sqrt(1.0 / 8.0);

Answer 2

首先你必须在主p1和p2以及p3中声明并初始化它们然后将它们传递给plane的构造函数：

#include <iostream>
using namespace std;
#include <cmath>

struct Vector3
{
    double x;
    double y;
    double z;
};


class Plane 
{
    Vector3 point, normal, p_p1, p_p2, p_p3;
public:
    Plane(Vector3 p1,
        Vector3 p2, Vector3 p3) : p_p1(p1), p_p2(p2), p_p3(p3){}
    double distance_to(const Vector3& p)const;
};

double Plane:: distance_to(const Vector3& p)const
{
    return get_hnf_d() + dot_product(p, get_normal()) ;
}

int main()
{
    Vector3 p1 = {sqrt(1.0 / 8.0), sqrt(1.0 / 8.0), sqrt(3.0 / 4.0)};
    // do the same thing as above
    Vector3 p2, p3;

    Plane _plane(p1, p2, p3);
    cout << "Distance to p1 is : " << _plane.distance_to(p1) << endl;



    return 0;
}

这只是一个非完整代码示例

无法从构造函数设置私有值

2 个答案: